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STAT RX USA LLC
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Manufacturer
STAT RX USA LLC
This medication contains important usage instructions, warnings, and side effect information that you should review before use.
When used in pregnancy during the second and third trimesters, drugs that act directly on the renin-angiotensin system can cause injury and even death to the developing fetus. When pregnancy is detected, Losartan Potassium and Hydrochlorothiazide Tablets should be discontinued as soon as possible. See WARNINGS, Fetal/Neonatal Morbidity and Mortality.
Losartan Potassium and Hydrochlorothiazide Tablets are indicated for the treatment of hypertension. This fixed dose combination is not indicated for initial therapy of hypertension, except when the hypertension is severe enough that the value of achieving prompt blood pressure control exceeds the risk of initiating combination therapy in these patients (see CLINICAL PHARMACOLOGY , Pharmacodynamics and Clinical Effects, and DOSAGE AND ADMINISTRATION ).
Hypertensive Patients with Left Ventricular Hypertrophy
Losartan Potassium and Hydrochlorothiazide Tablets are indicated to reduce the risk of stroke in patients with hypertension and left ventricular hypertrophy, but there is evidence that this benefit does not apply to Black patients (See PRECAUTIONS , Race, CLINICAL PHARMACOLOGY , Pharmacodynamics and Clinical Effects, Losartan Potassium, Reduction in the Risk of Stroke, Race, and DOSAGE AND ADMINISTRATION ).
Dosing must be individualized. The usual starting dose of losartan is 50 mg once daily, with 25 mg recommended for patients with intravascular volume depletion (e.g., patients treated with diuretics) (see WARNINGS , Hypotension ─ Volume-Depleted Patients ) and patients with a history of hepatic impairment (see WARNINGS , Impaired Hepatic Function ). Losartan can be administered once or twice daily at total daily doses of 25 to 100 mg. If the antihypertensive effect measured at trough using once-a-day dosing is inadequate, a twice-a-day regimen at the same total daily dose or an increase in dose may give a more satisfactory response.
Hydrochlorothiazide is effective in doses of 12.5 to 50 mg once daily and can be given at doses of 12.5 to 25 mg as Losartan Potassium and Hydrochlorothiazide Tablets.
To minimize dose-independent side effects, it is usually appropriate to begin combination therapy only after a patient has failed to achieve the desired effect with monotherapy.
The side effects (see WARNINGS ) of losartan are generally rare and apparently independent of dose; those of hydrochlorothiazide are a mixture of dose-dependent (primarily hypokalemia) and dose-independent phenomena (e.g., pancreatitis), the former much more common than the latter. Therapy with any combination of losartan and hydrochlorothiazide will be associated with both sets of dose-independent side effects.
Replacement Therapy: The combination may be substituted for the titrated components.
Dose Titration by Clinical Effect: A patient whose blood pressure is not adequately controlled with losartan monotherapy (see above) or hydrochlorothiazide alone, may be switched to Losartan Potassium and Hydrochlorothiazide Tablets 50 mg/12.5 mg (losartan 50 mg/hydrochlorothiazide 12.5 mg) once daily. If blood pressure remains uncontrolled after about 3 weeks of therapy, the dose may be increased to two tablets of Losartan Potassium and Hydrochlorothiazide 50 mg/12.5 mg once daily or one tablet of Losartan Potassium and Hydrochlorothiazide 100 mg/25 mg (losartan 100 mg/hydrochlorothiazide 25 mg) once daily. A patient whose blood pressure is not adequately controlled with losartan 100 mg monotherapy (see above) may be switched to Losartan Potassium and Hydrochlorothiazide Tablets 100 mg/12.5 mg once daily. If blood pressure remains uncontrolled after about 3 weeks of therapy, the dose may be increased to two tablets of Losartan Potassium and Hydrochlorothiazide 50 mg/12.5 mg once daily or one tablet of Losartan Potassium and Hydrochlorothiazide 100 mg/25 mg (losartan 100 mg/hydrochlorothiazide 25 mg) once daily.
A patient whose blood pressure is inadequately controlled by 25 mg once daily of hydrochlorothiazide, or is controlled but who experiences hypokalemia with this regimen, may be switched to Losartan Potassium and Hydrochlorothiazide Tablets 50 mg/12.5 mg (losartan 50 mg/hydrochlorothiazide 12.5 mg) once daily, reducing the dose of hydrochlorothiazide without reducing the overall expected antihypertensive response. The clinical response to Losartan Potassium and Hydrochlorothiazide Tablets 50 mg/12.5 mg should be subsequently evaluated, and if blood pressure remains uncontrolled after about 3 weeks of therapy, the dose may be increased to two tablets of Losartan Potassium and Hydrochlorothiazide Tablets 50 mg/12.5 mg once daily or one tablet of Losartan Potassium and Hydrochlorothiazide Tablets 100 mg/25 mg (losartan 100 mg/hydrochlorothiazide 25 mg) once daily.
The usual dose of Losartan Potassium and Hydrochlorothiazide is one tablet of Losartan Potassium and Hydrochlorothiazide 50 mg/12.5 mg once daily. More than two tablets of Losartan Potassium and Hydrochlorothiazide 50 mg/12.5 mg once daily or more than one tablet of Losartan Potassium and Hydrochlorothiazide 100 mg/25 mg once daily is not recommended. The maximal antihypertensive effect is attained about 3 weeks after initiation of therapy.
Use in Patients with Renal Impairment: The usual regimens of therapy with Losartan Potassium and Hydrochlorothiazide Tablets may be followed as long as the patient's creatinine clearance is >30 mL/min. In patients with more severe renal impairment, loop diuretics are preferred to thiazides, so Losartan Potassium and Hydrochlorothiazide Tablets are not recommended.
Patients with Hepatic Impairment: Losartan Potassium and Hydrochlorothiazide Tablets are not recommended for titration in patients with hepatic impairment (see WARNINGS , Impaired Hepatic function ) because the appropriate 25 mg starting dose of losartan cannot be given.
Severe Hypertension
The starting dose of Losartan Potassium and Hydrochlorothiazide Tablets for initial treatment of severe hypertension is one tablet of Losartan Potassium and Hydrochlorothiazide 50 mg/12.5 mg once daily (see CLINICAL PHARMACOLOGY , Pharmacodynamics and Clinical Effects). For patients who do not respond adequately to Losartan Potassium and Hydrochlorothiazide Tablets 50 mg/12.5 mg after 2 to 4 weeks of therapy, the dosage may be increased to one tablet of Losartan Potassium and Hydrochlorothiazide 100 mg/25 mg once daily. The maximum dose is one tablet of Losartan Potassium and Hydrochlorothiazide 100 mg/25 mg once daily. Losartan Potassium and Hydrochlorothiazide Tablets are not recommended as initial therapy in patients with hepatic impairment (see WARNINGS , Impaired Hepatic Function) because the appropriate 25 mg starting dose of losartan cannot be given. It is also not recommended for use as initial therapy in patients with intravascular volume depletion (e.g., patients treated with diuretics, see WARNINGS , Hypotension ─ Volume-Depleted Patients ).
Hypertensive Patients with Left Ventricular Hypertrophy
Treatment should be initiated with losartan potassium tablets 50 mg once daily. Hydrochlorothiazide 12.5 mg should be added or Losartan Potassium and Hydrochlorothiazide Tablets 50 mg/12.5 mg substituted if the blood pressure reduction is inadequate. If additional blood pressure reduction is needed, losartan potassium tablets 100 mg and hydrochlorothiazide 12.5 mg or Losartan Potassium and Hydrochlorothiazide Tablets 100 mg/12.5 mg may be substituted, followed by losartan potassium tablets 100 mg and hydrochlorothiazide 25 mg or Losartan Potassium and Hydrochlorothiazide Tablets 100 mg/25 mg. For further blood pressure reduction other antihypertensives should be added (see CLINICAL PHARMACOLOGY , Pharmacodynamics and Clinical Effects, Losartan Potassium, Reduction in the Risk of Stroke ).
Losartan Potassium and Hydrochlorothiazide Tablets may be administered with other antihypertensive agents.
Losartan Potassium and Hydrochlorothiazide Tablets may be administered with or without food.
Losartan potassium-hydrochlorothiazide has been evaluated for safety in 858 patients treated for essential hypertension and 3889 patients treated for hypertension and left ventricular hypertrophy. In clinical trials with losartan potassium-hydrochlorothiazide, no adverse experiences peculiar to this combination have been observed. Adverse experiences have been limited to those that were reported previously with losartan potassium and/or hydrochlorothiazide. The overall incidence of adverse experiences reported with the combination was comparable to placebo.
In general, treatment with losartan potassium-hydrochlorothiazide was well tolerated. For the most part, adverse experiences have been mild and transient in nature and have not required discontinuation of therapy. In controlled clinical trials, discontinuation of therapy due to clinical adverse experiences was required in only 2.8% and 2.3% of patients treated with the combination and placebo, respectively.
In these double-blind controlled clinical trials, the following adverse experiences reported with losartan-hydrochlorothiazide occurred in ≥1 percent of patients, and more often on drug than placebo, regardless of drug relationship:
|
|
Losartan Potassium- Hydrochlorothiazide (n=858) |
Placebo (n=173) |
|
Body
as
a
Whole
|
|
|
| Abdominal pain |
1.2 |
0.6 |
| Edema/swelling |
1.3 |
1.2 |
|
|
|
|
|
Cardiovascular
|
|
|
| Palpitation |
1.4 |
0 |
|
|
|
|
|
Musculoskeletal
|
|
|
| Back pain |
2.1 |
0.6 |
|
|
|
|
|
Nervous
/
Psychiatric
|
|
|
| Dizziness |
5.7 |
2.9 |
|
|
|
|
|
Respiratory
|
|
|
| Cough |
2.6 |
2.3 |
| Sinusitis |
1.2 |
0.6 |
| Upper respiratory infection |
6.1 |
4.6 |
|
|
|
|
|
Skin
|
|
|
| Rash |
1.4 |
0 |
The following adverse events were also reported at a rate of 1% or greater, but were as, or more, common in the placebo group in studies of essential hypertension: asthenia/fatigue, diarrhea, nausea, headache, bronchitis, pharyngitis.
Adverse events occurred at about the same rates in men and women. Adverse events were somewhat more frequent in the elderly compared to non-elderly patients and somewhat more frequent in Blacks compared to non-Blacks for both the losartan-hydrochlorothiazide and the control groups.
A patient with known hypersensitivity to aspirin and penicillin, when treated with losartan potassium, was withdrawn from study due to swelling of the lips and eyelids and facial rash, reported as angioedema, which returned to normal 5 days after therapy was discontinued.
Superficial peeling of palms and hemolysis were reported in one subject
treated with losartan potassium.
Other adverse experiences that have been reported with losartan, without regard to causality, are listed below:
Body as a Whole: chest pain, facial edema, fever, orthostatic effects, syncope
Cardiovascular: angina pectoris, arrhythmias including atrial fibrillation, sinus bradycardia, tachycardia, ventricular tachycardia and ventricular fibrillation, CVA, hypotension, myocardial infarction, second degree AV block
Digestive: anorexia, constipation, dental pain, dry mouth, dyspepsia, flatulence, gastritis, vomiting
General disorders and administration site conditions: malaise
Hematologic: anemia
Metabolic: gout
Musculoskeletal: arm pain, arthralgia, arthritis, fibromyalgia, hip pain, joint swelling, knee pain, leg pain, muscle cramps, muscle weakness, musculoskeletal pain, myalgia, shoulder pain, stiffness
Nervous System/Psychiatric: anxiety, anxiety disorder, ataxia, confusion, depression, dream abnormality, hypesthesia, insomnia, libido decreased, memory impairment, migraine, nervousness, panic disorder, paresthesia, peripheral neuropathy, sleep disorder, somnolence, tremor, vertigo
Respiratory: dyspnea, epistaxis, nasal congestion, pharyngeal discomfort, respiratory congestion, rhinitis, sinus disorder
Skin: alopecia, dermatitis, dry skin, ecchymosis, erythema, flushing, photosensitivity, pruritus, sweating, urticaria
Special Senses: blurred vision, burning/stinging in the eye, conjunctivitis, decrease in visual acuity, taste perversion, tinnitus
Urogenital: impotence, nocturia, urinary frequency, urinary tract infection.
Other adverse experiences that have been reported with hydrochlorothiazide, without regard to causality, are listed below:
Body as a Whole: weakness
Digestive: pancreatitis, jaundice (intrahepatic cholestatic jaundice), sialadenitis, cramping, gastric irritation
Hematologic: aplastic anemia, agranulocytosis, leukopenia, hemolytic anemia, thrombocytopenia
Hypersensitivity: purpura, photosensitivity, urticaria, necrotizing angiitis (vasculitis and cutaneous vasculitis), fever, respiratory distress including pneumonitis and pulmonary edema
Metabolic: hyperglycemia, glycosuria, hyperuricemia
Musculoskeletal: muscle spasm
Nervous System/Psychiatric: restlessness; Renal: renal failure, renal dysfunction, interstitial nephritis
Skin: erythema multiforme including Stevens-Johnson syndrome, exfoliative dermatitis including toxic epidermal necrolysis
Special Senses: transient blurred vision, xanthopsia.
Persistent dry cough (with an incidence of a few percent) has been associated with ACE-inhibitor use and in practice can be a cause of discontinuation of ACE-inhibitor therapy. Two prospective, parallel-group, double-blind, randomized, controlled trials were conducted to assess the effects of losartan on the incidence of cough in hypertensive patients who had experienced cough while receiving ACE-inhibitor therapy. Patients who had typical ACE-inhibitor cough when challenged with lisinopril, whose cough disappeared on placebo, were randomized to losartan 50 mg, lisinopril 20 mg, or either placebo (one study, n=97) or 25 mg hydrochlorothiazide (n=135). The double-blind treatment period lasted up to 8 weeks. The incidence of cough is shown below.
Study 1† HCTZ Losartan Lisinopril
—————————————————————————————————
Cough 25% 17% 69%
Study 2†† Placebo Losartan Lisinopril
—————————————————————————————————
Cough 35% 29% 62%
† Demographics = (89% caucasian, 64% female)
†† Demographics = (90% caucasian, 51% female)
These studies demonstrate that the incidence of cough associated with losartan therapy, in a population that all had cough associated with ACE-inhibitor therapy, is similar to that associated with hydrochlorothiazide or placebo therapy.
Cases of cough, including positive re-challenges, have been reported with the use of losartan in post-marketing experience.
Severe Hypertension: In a clinical study in patients with severe hypertension (SiDBP ≥110 mmHg), the overall pattern of adverse events reported through six weeks of follow-up was similar in patients treated with Losartan Potassium and Hydrochlorothiazide Tablets as initial therapy and in patients treated with losartan as initial therapy. There were no reported cases of syncope in either treatment group. There were 2 (0.6%) and 0 (0.0%) cases of hypotension reported in the group treated with Losartan Potassium and Hydrochlorothiazide Tablets and the group treated with losartan, respectively. There were 3 (0.8%) and 2 (1.2%) cases of increased serum creatinine (>0.5 mg/dL) in the group treated with Losartan Potassium and Hydrochlorothiazide Tablets and the group treated with losartan, respectively, during the same time period (See CLINICAL PHARMACOLOGY , Pharmacodynamics and Clinical Effects, Severe Hypertension ).
The following additional adverse reactions have been reported in post-marketing experience:
Digestive: Hepatitis has been reported rarely in patients treated with losartan.
Hemic: Thrombocytopenia.
Hypersensitivity: Angioedema, including swelling of the larynx and glottis, causing airway obstruction and/or swelling of the face, lips, pharynx, and/or tongue has been reported rarely in patients treated with losartan; some of these patients previously experienced angioedema with other drugs including ACE inhibitors. Vasculitis, including Henoch-Schönlein purpura, has been reported with losartan. Anaphylactic reactions have been reported.
Metabolic and Nutrition: Hyperkalemia, hyponatremia have been reported with losartan.
Musculoskeletal: Rare cases of rhabdomyolysis have been reported in patients receiving angiotensin II receptor blockers.
Respiratory: Dry cough (see above) has been reported with losartan.
Skin: Erythroderma has been reported with losartan.
Laboratory Test Findings
In controlled clinical trials, clinically important changes in standard laboratory parameters were rarely associated with administration of Losartan Potassium and Hydrochlorothiazide Tablets.
Creatinine, Blood Urea Nitrogen: Minor increases in blood urea nitrogen (BUN) or serum creatinine were observed in 0.6 and 0.8 percent, respectively, of patients with essential hypertension treated with Losartan Potassium and Hydrochlorothiazide Tablets alone. No patient discontinued taking Losartan Potassium and Hydrochlorothiazide Tablets due to increased BUN. One patient discontinued taking Losartan Potassium and Hydrochlorothiazide Tablets due to a minor increase in serum creatinine.
Hemoglobin and Hematocrit: Small decreases in hemoglobin and hematocrit (mean decreases of approximately 0.14 grams percent and 0.72 volume percent, respectively) occurred frequently in patients treated with Losartan Potassium and Hydrochlorothiazide Tablets alone, but were rarely of clinical importance. No patients were discontinued due to anemia.
Liver Function Tests: Occasional elevations of liver enzymes and/or serum bilirubin have occurred. In patients with essential hypertension treated with Losartan Potassium and Hydrochlorothiazide Tablets alone, no patients were discontinued due to these laboratory adverse experiences.
Serum Electrolytes: See PRECAUTIONS
Significant lethality was observed in mice and rats after oral administration of 1000 mg/kg and 2000 mg/kg, respectively, about 44 and 170 times the maximum recommended human dose on a mg/m2 basis.
Limited data are available in regard to overdosage in humans. The most likely manifestation of overdosage would be hypotension and tachycardia; bradycardia could occur from parasympathetic (vagal) stimulation. If symptomatic hypotension should occur, supportive treatment should be instituted.
Neither losartan nor its active metabolite can be removed by hemodialysis.
Hydrochlorothiazide
The oral LD50 of hydrochlorothiazide is greater than 10 g/kg in both mice and rats. The most common signs and symptoms observed are those caused by electrolyte depletion (hypokalemia, hypochloremia, hyponatremia) and dehydration resulting from excessive diuresis. If digitalis has also been administered, hypokalemia may accentuate cardiac arrhythmias. The degree to which hydrochlorothiazide is removed by hemodialysis has not been established.
Losartan Potassium and Hydrochlorothiazide 50 mg/12.5 mg, Losartan Potassium and Hydrochlorothiazide 100 mg/12.5 mg and Losartan Potassium and Hydrochlorothiazide 100 mg/25 mg combine an angiotensin II receptor (type AT1) antagonist and a diuretic, hydrochlorothiazide.
Losartan potassium, a non-peptide molecule, is chemically described as 2-butyl-4-chloro-1-[p-(o-1H-tetrazol-5-ylphenyl)benzyl]imidazole-5-methanol monopotassium salt. Its empirical formula is C22H22ClKN6O, and its structural formula is:
[image: MM1]
Losartan potassium, USP is a white to off-white free-flowing crystalline powder with a molecular weight of 461.01. It is freely soluble in water, soluble in alcohols, and slightly soluble in common organic solvents, such as acetonitrile and methyl ethyl ketone.
Oxidation of the 5-hydroxymethyl group on the imidazole ring results in the active metabolite of losartan.
Hydrochlorothiazide is 6-chloro-3,4-dihydro-2H-1,2,4-benzothiadiazine-7-sulfonamide 1,1-dioxide. Its empirical formula is C7H8ClN3O4S2 and its structural formula is:
[image: MM2]
Hydrochlorothiazide, USP is a white, or practically white, crystalline powder with a molecular weight of 297.74, which is slightly soluble in water, but freely soluble in sodium hydroxide solution.
Losartan Potassium and Hydrochlorothiazide Tablets, USP are available for oral administration in three tablet combinations of losartan and hydrochlorothiazide. Losartan Potassium and Hydrochlorothiazide Tablets, USP 50 mg/12.5 mg contain 50 mg of losartan potassium USP and 12.5 mg of hydrochlorothiazide USP. Losartan Potassium and Hydrochlorothiazide Tablets, USP 100 mg/12.5 mg contain 100 mg of losartan potassium USP and 12.5 mg of hydrochlorothiazide USP. Losartan Potassium and Hydrochlorothiazide Tablets, USP 100 mg/25 mg contain 100 mg of losartan potassium USP and 25 mg of hydrochlorothiazide USP. Inactive ingredients are colloidal silicon dioxide, hydroxypropyl cellulose, hypromellose, lactose anhydrous, magnesium stearate, microcrystalline cellulose, pregelatinized starch, talc and titanium dioxide. Losartan Potassium and Hydrochlorothiazide Tablets, USP 50 mg/12.5 mg and Losartan Potassium and Hydrochlorothiazide Tablets, USP 100 mg/25 mg also contain D and C yellow No. 10 lake.
Losartan Potassium and Hydrochlorothiazide Tablets, USP 50 mg/12.5 mg contain 4.24 mg (0.108 mEq) of potassium, Losartan Potassium and Hydrochlorothiazide Tablets, USP 100 mg/12.5 mg contain 8.48 mg (0.216 mEq) of potassium, and Losartan Potassium and Hydrochlorothiazide Tablets, USP 100 mg/25 mg contain 8.48 mg (0.216 mEq) of potassium.
[image: MM4]
Losartan Potassium and Hydrochlorothiazide Tablets, USP 50 mg/12.5 mg are light yellow colored, oval shaped, biconvex film coated tablets, debossed with "116" on one side and plain on other side.
Bottles of 30 NDC 13668-116-30
Bottles of 90 NDC 13668-116-90
Bottles of 1000 NDC 13668-116-10
100 Unit Dose Tablets NDC 13668-116-74
Losartan Potassium and Hydrochlorothiazide Tablets, USP 100 mg/12.5 mg are white to off white colored, oval shaped, biconvex film coated tablets, debossed with "1117" on one side and plain on other side.
Bottles of 30 NDC 13668-117-30
Bottles of 90 NDC 13668-117-90
Bottles of 1000 NDC 13668-117-10
100 Unit Dose Tablets NDC 13668-117-74
Losartan Potassium and Hydrochlorothiazide Tablets, USP 100 mg/25 mg are yellow colored, oval shaped, biconvex film coated tablets, debossed with "1118" on one side and plain on other side.
Bottles of 30 NDC 13668-118-30
Bottles of 90 NDC 13668-118-90
Bottles of 1000 NDC 13668-118-10
100 Unit Dose Tablets NDC 13668-118-74
Store at 20° to 25°C (68° to 77°F) (See USP controlled room temperature). Protect from light.
Keep container tightly closed.
[image: MM3]
TORRENT PHARMACEUTICALS LTD., Indrad-382 721, Dist. Mehsana, INDIA.
For:
TORRENT PHARMA INC., 5380 Holiday Terrace, Suite 40, Kalamazoo, Michigan 49009.
8025591 Revised September 2010
Photos of the product and/or packaging supplied by the manufacturer.
Angiotensin II [formed from angiotensin I in a reaction catalyzed by angiotensin converting enzyme (ACE, kininase II)], is a potent vasoconstrictor, the primary vasoactive hormone of the renin-angiotensin system and an important component in the pathophysiology of hypertension. It also stimulates aldosterone secretion by the adrenal cortex. Losartan and its principal active metabolite block the vasoconstrictor and aldosterone-secreting effects of angiotensin II by selectively blocking the binding of angiotensin II to the AT1 receptor found in many tissues (e.g., vascular smooth muscle, adrenal gland). There is also an AT2 receptor found in many tissues but it is not known to be associated with cardiovascular homeostasis. Both losartan and its principal active metabolite do not exhibit any partial agonist activity at the AT1 receptor and have much greater affinity (about 1000-fold) for the AT1 receptor than for the AT2 receptor. In vitro binding studies indicate that losartan is a reversible, competitive inhibitor of the AT1 receptor. The active metabolite is 10 to 40 times more potent by weight than losartan and appears to be a reversible, non-competitive inhibitor of the AT1 receptor.
Neither losartan nor its active metabolite inhibits ACE (kininase II, the enzyme that converts angiotensin I to angiotensin II and degrades bradykinin); nor do they bind to or block other hormone receptors or ion channels known to be important in cardiovascular regulation.
Hydrochlorothiazide is a thiazide diuretic. Thiazides affect the renal tubular mechanisms of electrolyte reabsorption, directly increasing excretion of sodium and chloride in approximately equivalent amounts. Indirectly, the diuretic action of hydrochlorothiazide reduces plasma volume, with consequent increases in plasma renin activity, increases in aldosterone secretion, increases in urinary potassium loss, and decreases in serum potassium. The renin-aldosterone link is mediated by angiotensin II, so coadministration of an angiotensin II receptor antagonist tends to reverse the potassium loss associated with these diuretics.
The mechanism of the antihypertensive effect of thiazides is unknown.
Pharmacokinetics
General
Losartan PotassiumLosartan is an orally active agent that undergoes substantial first-pass metabolism by cytochrome P450 enzymes. It is converted, in part, to an active carboxylic acid metabolite that is responsible for most of the angiotensin II receptor antagonism that follows losartan treatment. The terminal half-life of losartan is about 2 hours and of the metabolite is about 6-9 hours. The pharmacokinetics of losartan and its active metabolite are linear with oral losartan doses up to 200 mg and do not change over time. Neither losartan nor its metabolite accumulate in plasma upon repeated once-daily dosing.
Following oral administration, losartan is well absorbed (based on absorption of radiolabeled losartan) and undergoes substantial first-pass metabolism; the systemic bioavailability of losartan is approximately 33%. About 14% of an orally-administered dose of losartan is converted to the active metabolite. Mean peak concentrations of losartan and its active metabolite are reached in 1 hour and in 3-4 hours, respectively. While maximum plasma concentrations of losartan and its active metabolite are approximately equal, the AUC of the metabolite is about 4 times as great as that of losartan. A meal slows absorption of losartan and decreases its Cmax but has only minor effects on losartan AUC or on the AUC of the metabolite (about 10% decreased).
Both losartan and its active metabolite are highly bound to plasma proteins, primarily albumin, with plasma free fractions of 1.3% and 0.2%, respectively. Plasma protein binding is constant over the concentration range achieved with recommended doses. Studies in rats indicate that losartan crosses the blood-brain barrier poorly, if at all.
Losartan metabolites have been identified in human plasma and urine. In addition to the active carboxylic acid metabolite, several inactive metabolites are formed. Following oral and intravenous administration of 14C-labeled losartan potassium, circulating plasma radioactivity is primarily attributed to losartan and its active metabolite. In vitro studies indicate that cytochrome P450 2C9 and 3A4 are involved in the biotransformation of losartan to its metabolites. Minimal conversion of losartan to the active metabolite (less than 1% of the dose compared to 14% of the dose in normal subjects) was seen in about one percent of individuals studied.
The volume of distribution of losartan is about 34 liters and of the active metabolite is about 12 liters. Total plasma clearance of losartan and the active metabolite is about 600 mL/min and 50 mL/min, respectively, with renal clearance of about 75 mL/min and 25 mL/min, respectively. When losartan is administered orally, about 4% of the dose is excreted unchanged in the urine and about 6% is excreted in urine as active metabolite. Biliary excretion contributes to the elimination of losartan and its metabolites. Following oral 14C-labeled losartan, about 35% of radioactivity is recovered in the urine and about 60% in the feces. Following an intravenous dose of 14C-labeled losartan, about 45% of radioactivity is recovered in the urine and 50% in the feces.
Pediatric: Losartan pharmacokinetics have been investigated in patients 6 to 16 years (see PRECAUTIONS , Pediatric Use).
Geriatric and Gender: Losartan pharmacokinetics have been investigated in the elderly (65-75 years) and in both genders. Plasma concentrations of losartan and its active metabolite are similar in elderly and young hypertensives. Plasma concentrations of losartan were about twice as high in female hypertensives as male hypertensives, but concentrations of the active metabolite were similar in males and females.
Race: Pharmacokinetic differences due to race have not been studied (see also PRECAUTIONS , Race and CLINICAL PHARMACOLOGY , Pharmacodynamics and Clinical Effects, Losartan Potassium, Reduction in the Risk of Stroke, Race).
Losartan: Following oral administration, plasma concentrations and AUCs of losartan and its active metabolite are increased by 50-90% in patients with mild (creatinine clearance of 50 to 74 mL/min) or moderate (creatinine clearance 30 to 49 mL/min) renal insufficiency. In this study, renal clearance was reduced by 55-85% for both losartan and its active metabolite in patients with mild or moderate renal insufficiency. Neither losartan nor its active metabolite can be removed by hemodialysis.
Hydrochlorothiazide: Following oral administration, the AUC for hydrochlorothiazide is increased by 70 and 700% for patients with mild and moderate renal insufficiency, respectively. In this study, renal clearance of hydrochlorothiazide decreased by 45 and 85% in patients with mild and moderate renal impairment, respectively.
The usual regimens of therapy with Losartan Potassium and Hydrochlorothiazide Tablets may be followed as long as the patient's creatinine clearance is >30 mL/min. In patients with more severe renal impairment, loop diuretics are preferred to thiazides, so Losartan Potassium and Hydrochlorothiazide Tablets are not recommended (See DOSAGE AND ADMINISTRATION ).
Hepatic Insufficiency: Following oral administration in patients with mild to moderate alcoholic cirrhosis of the liver, plasma concentrations of losartan and its active metabolite were, respectively, 5 times and about 1.7 times those in young male volunteers. Compared to normal subjects, the total plasma clearance of losartan in patients with hepatic insufficiency was about 50% lower, and the oral bioavailability was about 2 times higher. The lower starting dose of losartan recommended for use in patients with hepatic impairment cannot be given using Losartan Potassium and Hydrochlorothiazide Tablets. Its use in such patients as a means of losartan titration is, therefore, not recommended (see DOSAGE AND ADMINISTRATION ).
Drug Interactions
Losartan PotassiumLosartan, administered for 12 days, did not affect the pharmacokinetics or pharmacodynamics of a single dose of warfarin. Losartan did not affect the pharmacokinetics of oral or intravenous digoxin. There is no pharmacokinetic interaction between losartan and hydrochlorothiazide. Coadministration of losartan and cimetidine led to an increase of about 18% in AUC of losartan but did not affect the pharmacokinetics of its active metabolite. Coadministration of losartan and phenobarbital led to a reduction of about 20% in the AUC of losartan and that of its active metabolite. A somewhat greater interaction (approximately 40% reduction in the AUC of active metabolite and approximately 30% reduction in the AUC of losartan) has been reported with rifampin. Fluconazole, an inhibitor of cytochrome P450 2C9, decreased the AUC of the active metabolite by approximately 40%, but increased the AUC of losartan by approximately 70% following multiple doses. Conversion of losartan to its active metabolite after intravenous administration is not affected by ketoconazole, an inhibitor of P450 3A4. The AUC of active metabolite following oral losartan was not affected by erythromycin, another inhibitor of P450 3A4, but the AUC of losartan was increased by 30%.
After oral administration of hydrochlorothiazide, diuresis begins within 2 hours, peaks in about 4 hours and lasts about 6 to 12 hours.
Hydrochlorothiazide is not metabolized but is eliminated rapidly by the kidney. When plasma levels have been followed for at least 24 hours, the plasma half-life has been observed to vary between 5.6 and 14.8 hours. At least 61 percent of the oral dose is eliminated unchanged within 24 hours. Hydrochlorothiazide crosses the placental but not the blood-brain barrier and is excreted in breast milk.
Hypertension: Losartan inhibits the pressor effect of angiotensin II (as well as angiotensin I) infusions. A dose of 100 mg inhibits the pressor effect by about 85% at peak with 25-40% inhibition persisting for 24 hours. Removal of the negative feedback of angiotensin II causes a 2- to 3-fold rise in plasma renin activity and consequent rise in angiotensin II plasma concentration in hypertensive patients. Losartan does not affect the response to bradykinin, whereas ACE inhibitors increase the response to bradykinin. Aldosterone plasma concentrations fall following losartan administration. In spite of the effect of losartan on aldosterone secretion, very little effect on serum potassium was observed.
In a single-dose study in normal volunteers, losartan had no effects on glomerular filtration rate, renal plasma flow or filtration fraction. In multiple-dose studies in hypertensive patients, there were no notable effects on systemic or renal prostaglandin concentrations, fasting triglycerides, total cholesterol or HDL-cholesterol or fasting glucose concentrations. There was a small uricosuric effect leading to a minimal decrease in serum uric acid (mean decrease less than 0.4 mg/dL) during chronic oral administration.
The antihypertensive effects of losartan were demonstrated principally in 4 placebo-controlled, 6- to 12-week trials of dosages from 10 to 150 mg per day in patients with baseline diastolic blood pressures of 95-115. The studies allowed comparisons of two doses (50-100 mg/day) as once-daily or twice-daily regimens, comparisons of peak and trough effects, and comparisons of response by gender, age, and race. Three additional studies examined the antihypertensive effects of losartan and hydrochlorothiazide in combination.
The 4 studies of losartan monotherapy included a total of 1075 patients randomized to several doses of losartan and 334 to placebo. The 10 and 25 mg doses produced some effect at peak (6 hours after dosing) but small and inconsistent trough (24 hour) responses. Doses of 50, 100, and 150 mg once daily gave statistically significant systolic/diastolic mean decreases in blood pressure, compared to placebo in the range of 5.5-10.5/3.5-7.5 mmHg, with the 150 mg dose giving no greater effect than 50-100 mg. Twice-daily dosing at 50-100 mg/day gave consistently larger trough responses than once-daily dosing at the same total dose. Peak (6 hour) effects were uniformly, but moderately larger than trough effects, with the trough to peak ratio for systolic and diastolic responses 50-95% and 60-90%, respectively.
Analysis of age, gender, and race subgroups of patients showed that men and women, and patients over and under 65, had generally similar responses. Losartan was effective in reducing blood pressure regardless of race, although the effect was somewhat less in Black patients (usually a low-renin population).
The effect of losartan is substantially present within one week but in some studies the maximal effect occurred in 3-6 weeks. In long-term follow-up studies (without placebo control) the effect of losartan appeared to be maintained for up to a year. There is no apparent rebound effect after abrupt withdrawal of losartan. There was essentially no change in average heart rate in losartan-treated patients in controlled trials.
Reduction in the Risk of Stroke: The Losartan Intervention For Endpoint reduction in hypertension (LIFE) study was a multinational, double-blind study comparing losartan and atenolol in 9193 hypertensive patients with ECG-documented left ventricular hypertrophy. Patients with myocardial infarction or stroke within six months prior to randomization were excluded. Patients were randomized to receive once daily losartan 50 mg or atenolol 50 mg. If goal blood pressure (less than 140/90 mmHg) was not reached, hydrochlorothiazide (12.5 mg) was added first and, if needed, the dose of losartan or atenolol was then increased to 100 mg once daily. If necessary, other antihypertensive treatments (e.g., increase in dose of hydrochlorothiazide therapy to 25 mg or addition of other diuretic therapy, calcium-channel blockers, alpha-blockers, or centrally acting agents, but not ACE inhibitors, angiotensin II antagonists, or beta-blockers) were added to the treatment regimen to reach the goal blood pressure.
In efforts to control blood pressure, the patients in both arms of the LIFE study were coadministered hydrochlorothiazide the majority of time they were on study drug (73.9% and 72.4% of days in the losartan and atenolol arms, respectively).
Of the randomized patients, 4963 (54%) were female and 533 (6%) were Black. The mean age was 67 with 5704 (62%) age ≥65. At baseline, 1195 (13%) had diabetes, 1326 (14%) had isolated systolic hypertension, 1469 (16%) had coronary heart disease, and 728 (8%) had cerebrovascular disease. Baseline mean blood pressure was 174/98 mmHg in both treatment groups. The mean length of follow-up was 4.8 years. At the end of study or at the last visit before a primary endpoint, 77% of the group treated with losartan and 73% of the group treated with atenolol were still taking study medication. Of the patients still taking study medication, the mean doses of losartan and atenolol were both about 80 mg/day, and 15% were taking atenolol or losartan as monotherapy, while 77% were also receiving hydrochlorothiazide (at a mean dose of 20 mg/day in each group). Blood pressure reduction measured at trough was similar for both treatment groups but blood pressure was not measured at any other time of the day. At the end of study or at the last visit before a primary endpoint, the mean blood pressures were 144.1/81.3 mmHg for the group treated with losartan and 145.4/80.9 mmHg for the group treated with atenolol [the difference in SBP of 1.3 mmHg was significant (p less than 0.001), while the difference of 0.4 mmHg in DBP was not significant (p=0.098)].
The primary endpoint was the first occurrence of cardiovascular death, nonfatal stroke, or nonfatal myocardial infarction. Patients with nonfatal events remained in the trial, so that there was also an examination of the first event of each type even if it was not the first event (e.g., a stroke following an initial myocardial infarction would be counted in the analysis of stroke). Treatment with losartan resulted in a 13% reduction (p=0.021) in risk of the primary endpoint compared to the atenolol group; this difference was primarily the result of an effect on fatal and nonfatal stroke. Treatment with losartan reduced the risk of stroke by 25% relative to atenolol (p=0.001).
For additional details on the LIFE study see the label for Losartan Potassium Tablets.
Race: In the LIFE study, Black patients treated with atenolol were at lower risk of experiencing the primary composite endpoint compared with Black patients treated with losartan. In the subgroup of Black patients (n=533, 6% of the LIFE study patients), there were 29 primary endpoints among 263 patients on atenolol (11%, 26 per 1000 patient-years) and 46 primary endpoints among 270 patients (17%, 42 per 1000 patient-years) on losartan. This finding could not be explained on the basis of differences in the populations other than race or on any imbalances between treatment groups. In addition, blood pressure reductions in both treatment groups were consistent between Black and non-Black patients. Given the difficulty in interpreting subset differences in large trials, it cannot be known whether the observed difference is the result of chance. However, the LIFE study provides no evidence that the benefits of losartan on reducing the risk of cardiovascular events in hypertensive patients with left ventricular hypertrophy apply to Black patients.
The 3 controlled studies of losartan and hydrochlorothiazide included over 1300 patients assessing the antihypertensive efficacy of various doses of losartan (25, 50 and 100 mg) and concomitant hydrochlorothiazide (6.25, 12.5 and 25 mg). A factorial study compared the combination of losartan/hydrochlorothiazide 50 mg/12.5 mg with its components and placebo. The combination of losartan/hydrochlorothiazide 50 mg/12.5 mg resulted in an approximately additive placebo-adjusted systolic/diastolic response (15.5/9.0 mmHg for the combination compared to 8.5/5.0 mmHg for losartan alone and 7.0/3.0 mmHg for hydrochlorothiazide alone). Another study investigated the dose-response relationship of various doses of hydrochlorothiazide (6.25, 12.5 and 25 mg) or placebo on a background of losartan (50 mg) in patients not adequately controlled (sitting diastolic blood pressure [SiDBP] 93-120 mmHg) on losartan (50 mg) alone. The third study investigated the dose-response relationship of various doses of losartan (25, 50 and 100 mg) or placebo on a background of hydrochlorothiazide (25 mg) in patients not adequately controlled (SiDBP 93-120 mmHg) on hydrochlorothiazide (25 mg) alone. These studies showed an added antihypertensive response at trough (24 hours post-dosing) of hydrochlorothiazide 12.5 or 25 mg added to losartan 50 mg of 5.5/3.5 and 10.0/6.0 mmHg, respectively. Similarly, there was an added antihypertensive response at trough when losartan 50 or 100 mg was added to hydrochlorothiazide 25 mg of 9.0/5.5 and 12.5/6.5 mmHg, respectively. There was no significant effect on heart rate.
There was no difference in response for men and women or in patients over or under 65 years of age.
Black patients had a larger response to hydrochlorothiazide than non-Black patients and a smaller response to losartan. The overall response to the combination was similar for Black and non-Black patients.
Severe Hypertension (Sitting Diastolic Blood Pressure [SiDBP] ≥110 mmHg)
The safety and efficacy of Losartan Potassium and Hydrochlorothiazide Tablets as initial therapy for severe hypertension (defined as a mean SiDBP ≥110 mmHg confirmed on 2 separate occasions off all antihypertensive therapy) was studied in a 6-week double-blind, randomized, multicenter study. Patients were randomized to either losartan and hydrochlorothiazide (50 mg/12.5 mg, once daily) or to losartan (50 mg, once daily) and followed for blood pressure response. Patients were titrated at 2-week intervals if their SiDBP did not reach goal (less than 90 mmHg). Patients on combination therapy were titrated from losartan 50 mg/hydrochlorothiazide 12.5 mg to losartan 50 mg/hydrochlorothiazide 12.5 mg (sham titration to maintain the blind) to losartan 100 mg/hydrochlorothiazide 25 mg. Patients on monotherapy were titrated from losartan 50 mg to losartan 100 mg to losartan 150 mg, as needed. The primary endpoint was a comparison at 4 weeks of patients who achieved goal diastolic blood pressure (trough SiDBP less than 90 mmHg).
The study enrolled 585 patients, including 264 (45%) females, 124 (21%) Blacks, and 21 (4%) ≥65 years of age. The mean blood pressure at baseline for the total population was 171/113 mmHg. The mean age was 53 years. After 4 weeks of therapy, the mean SiDBP was 3.1 mmHg lower and the mean SiSBP was 5.6 mmHg lower in the group treated with Losartan Potassium and Hydrochlorothiazide Tablets. As a result, a greater proportion of the patients on Losartan Potassium and Hydrochlorothiazide Tablets reached the target diastolic blood pressure (17.6% for Losartan Potassium and Hydrochlorothiazide Tablets, 9.4% for losartan; p=0.006). Similar trends were seen when the patients were grouped according to gender, race or age (less than, ≥ 65).
After 6 weeks of therapy, more patients who received the combination regimen reached target diastolic blood pressure than those who received the monotherapy regimen (29.8% versus 12.5%).
During the study period, there were no reported cases of syncope in either treatment group. There were 2 (0.6%) and 0 (0.0%) cases of hypotension reported in the group treated with Losartan Potassium and Hydrochlorothiazide Tablets and the group treated with losartan, respectively. The overall pattern of adverse events reported for patients treated with Losartan Potassium and Hydrochlorothiazide Tablets as initial therapy was similar to the adverse event profile for patients treated with losartan as initial therapy. For information on the specific adverse events observed during the study period, see ADVERSE REACTIONS , Severe Hypertension.
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