Losartan potassium, hydrochlorothiazide.
Co-Normoten: Each tablet contains: Losartan potassium 50 mg and hydrochlorothiazide 12.5 mg.
Co-Normoten DS: Each film-coated tablet contains Losartan Potassium 100 mg and hydrochlorothiazide 25 mg.
Pharmacology: Mechanism of Action: Angiotensin II [formed from angiotensin I in a reaction catalyzed by angiotensin converting enzyme (ACE, kinase 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 selectively blocking the binding of angiotensin II to the AT1 receptor found in the 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 antagonist activity at the AT1 receptor and much greater activity (about 1000 fold) at 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 reversible, non-competitive inhibitor of the AT1 receptor. Neither Losartan nor its active metabolite inhibits ACE (kinase 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 electrolytes reabsorption, directly increasing excretion of sodium and chloride in approximately equal amounts. Indirectly, the diuretic action of Hydrochlorothiazide reduces plasma volume, with consequent increase in plasma renin activity, increase in aldosterone secretion, increase in urinary potassium loss and decrease in serum potassium. The renin-aldosterone link is mediated by angiotensin II, so co-administration of an angiotensin II antagonist tends to reverse the potassium loss associated with these diuretics.
Pharmacokinetics: Co-Normoten: Following oral administration, Losartan is well absorbed 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 plasma concentrations of Losartan and its metabolite are reached in 1 hour and 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% decrease). 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. Studies in rats indicate that Losartan crosses the Blood-brain barrier poorly, if at all. About 4% of the dose is excreted unchanged in urine and about 6% is excreted in urine as active metabolite. Biliary excretion contributes to the excretion of Losartan and its metabolites. Losartan pharmacokinetics have been investigated in patients <18 years of age, in the elderly (65-75 years) and in both genders. Plasma concentrations of Losartan is about twice as high in female hypertensives then in male hypertensives, but concentrations of the active metabolite are similar in males and females. No dosage adjustments is necessary.
Hydrohlorothiazide is well absorbed. The plasma half-life of Hydrochlorothiazide varies between 5.6 to 14.8 hours. Hydrochlorothiazide crosses the placental but not the blood brain barrier. It is excreted in breast milk. Hydrochlorothiazide is eliminated primarily by renal pathways and 95% of the absorbed dose is excreted in the urine as unchanged drug.
Co-Normoten DS: LOSARTAN: Losartan is an orally active ingredient 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 to 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 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 metabolite are reached in 1 hour and 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% decrease). 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 on 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 studies. 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 urine and about 6% is excreted in urine as active metabolite. Biliary excretion contributes to the excretion 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. Hydrochlorothiazide is well absorbed. The plasma half-life of Hydrochlorothiazide varies between 5.6 to 14.8 hours. Hydrochlorothiazide crosses the placenta but not the blood brain barrier. It is excreted in breast milk. Hydrochlorothiazide is eliminated primarily by renal pathways and 95% of the absorbed dose is excreted in the urine as unchanged drug.
Special Populations: Pediatric: Losartan pharmacokinetics have not been investigated in patients <18 years of age.
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 in male hypertensives, but concentrations of the active metabolite are similar in males and females.
Renal Insufficiency: Following oral administration of Losartan 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 to moderate renal insufficiency. Neither losartan nor its active metabolite can be removed by hemodialysis. Following administration of Hydrochlorothiazide, the AUC of 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 + Hydrochlorothiazide may be followed as long as the patients creatinine clearance is >30 mL/min. In patients with more severe renal impairment, loop diuretics are preferred than thiazides, so Losartan + Hydrochlorothiazide is not recommended.
Hepatic Insufficiency: Following oral administration in patients with mild than 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 total bioavailability was about 2 times higher. The lower starting dose of losartan recommended for use in patients with hepatic therefore not recommended.
Co-Normoten: It is indicated for the treatment of hypertension, unresponsive to either Losartan Potassium or Hydrochlorothiazide monotherapy.
Co-Normoten DS: It is indicated for the treatment of hypertension. This fixed dose combination is not indicated for initial therapy of hypertension, except when hypertension is severe enough that the value of achieving prompt blood pressure control exceeds the risk of initiating combination therapy in these patients.
Co-Normoten: The usual starting dose for patient whose blood pressure is not adequately controlled by Losartan Potassium or Hydrochlorothiazide monotherapy is one tablet per day. If the blood pressure remains uncontrolled after about three weeks of therapy, the dose may be increased to two tablets per day. More than two tablets per day is not recommended. It may be administered with or without food.
Co-Normoten DS: Hypertension: 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) and patients with a history of hepatic impairment. Losartan can be administered once or twice daily doses of 25 to 100 mg. If the antihypertensive effect measured at trough using once-a-day dosing is adequate, 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 mg to 25 mg.
To minimize dose-dependent 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 of losartan are generally rare and apparently independent of dose; those 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-dependent 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 or hydrochlorothiazide alone, may be switched to Losartan Potassium + Hydrochlorothiazide 50 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 + Hydrochlorothiazide 50 mg/12.5 mg once daily or one tablet Losartan Potassium + Hydrochlorothiazide 100 mg/25 mg once daily. A patient whose blood pressure is inadequately controlled by 25 mg once daily of hydrochlorothiazide, or is controlled but experiences hypokalemia with this regimen, may be switched to Losartan potassium + Hydrochlorothiazide 50 mg/12.5 mg once daily, reducing the dose of hydrochlorothiazide without reducing the overall expected antihypertensive response. The clinical response to Losartan Potassium + Hydrochlorothiazide 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 + Hydrochlorothiazide 50 mg/12.5 mg once daily or one tablet of Losartan Potassium + Hydrochlorothiazide 100 mg/25 mg once daily.
The usual dose of Losartan Potassium + Hydrochlorothiazide 50 mg/12.5 mg is one tablet once daily. More than two tablets of Losartan Potassium + Hydrochlorothiazide 50 mg/12.5 mg once daily or more than one tablet of Losartan Potassium + 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 + Hydrochlorothiazide may be followed as long as the patients creatinine clearance is >30 mL/min.
Patients with Hepatic Impairment: Losartan Potassium + Hydrochlorothiazide is not recommended for titration in patients with hepatic impairment because the appropriate 25 mg starting dose of losartan cannot be given.
Severe Hypertension: The starting dose for initial treatment of severe hypertension is one tablet of Losartan Potassium + Hydrochlorothiazide 50 mg/12.5 mg once daily. For patients who do not respond adequately with Losartan Potassium + Hydrochlorothiazide 50 mg/12.5 mg after 2 to 4 weeks of therapy, the dosage may be increased to one tablet of Losartan Potassium + Hydrochlorothiazide 50 mg/25 mg once daily. The maximum dose is one tablet of Losartan Potassium + Hydrochlorothiazide 50 mg/12.5 mg once daily.
Losartan Potassium: Co-Normoten: Significant lethality was observed on mice and rats, after oral administration of 1000mg/kg and 2000mg/kg of Losartan Potassium respectively. The most likely manifestation of overdosage will be hypotension and tachycardia, bradycardia could occur from parasympathetic (vagal) stimulation. If symptomatic hypotension occurs, supportive treatment should be instituted.
Co-Normoten DS: Significant lethality was observed on mice and rats after oral administration of 1000 mg/kg and 2000 mg/kg of Losartan potassium respectively about 44 and 170 times the maximum recommended human dose on a mg/m2 basis. The most likely manifestation of overdosage will be hypotension and tachycardia, bradycardia could occur from parasympathetic (vagal) stimulation. If symptomatic hypotension occurs, supportive treatment should be instituted.
Hydrochlorothiazide: The oral LD50 of Hydrochlorothiazide is greater than 10g/kg in both mice and rats. The most common signs and symptoms are those caused by electrolyte depletion, such as hypokalemia, hypochloremia, hyponatremia and dehydration resulting from excessive diuresis. If digitalis has also been administered, hypokalemia might accentuate cardiac arrhythmias. The degree to which Hydrochlorothiazide is removed by hemodialysis has not been established.
It is contraindicated in patients who are hypersensitive to Losartan potassium or Hydrochlorothiazide. Because of Hydrochlorothiazide component, it is contraindicated in patients with anuria or hypersensitivity to other sulphonamide-derived drugs.
Co-Normoten: It is not recommended for patients with impaired liver function. As a consequence of inhibiting the renin-angiotensin-aldosterone system, changes in renal function have been reported in susceptible individual treated with Losartan Potassium. In some patients these changes were reversible upon discontinuation of therapy.
In patients whose renal function may depend on the activity of the renin-angiotensin aldosterone system (e.g. Patients with severe congestive heart failure), treatment with Losartan Potassium may lead to oliguria and/or progressive azotemia and rarely with acute renal failure and/or death. In patients with unilateral or bilateral renal artery stenosis, increase in serum creatinine or blood urea nitrogen (BUN) have been reported with oral administration of Losartan Potassium.
In some patients these changes were reversible upon discontinuation of therapy.
It is not known that Losartan Potassium is excreted in human milk. But significant levels of Losartan and its metabolite were shown in rat milk. Thiazides appear in human milk. Because of the potential of the adverse effects on nursing infants, a decision should be made on whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
No overall differences in effectiveness or safety were observed between elder and younger patients but greater sensitivity of some older individuals cannot be ruled out.
In patients who are intravascularly volume depleted (e.g. those treated with diuretics), symptomatic hypotension may occur after initiation of therapy with Losartan Potassium and Hydrochlorothiazide tablet.
The use of product should be avoided in patients with Systemic Lupus Erythematosus.
Concomitant use of Lithium should be avoided.
Co-Normoten DS: Fetal/Neonatal/Morbidity and Mortality: Drugs that act directly on the renin-angiotensin system can cause fetal and neonatal morbidity and death when administered to pregnant women. When pregnancy is detected, Losartan Potassium + Hydrochlorothiazide should be discontinued as soon as possible. The use of drugs that act directly on the renin-angiotensin system during the second or third trimester of pregnancy has been associated with fetal or neonatal injury, including hypotension, neonatal skull hypoplasia, anuria, reversible or irreversible renal failure, and death. Oligohydramnios has also been reported, presumably resulting from decreased fetal renal function; oligohydramnios in this setting has been associated with fetal limb conctractures, craniofacial deformation, and hypoplastic lung development. Prematurity, intrauterine growth retardation, and patent ductus arteriosus have also been reported, although it is not clear whether these occurrences were due to exposure to the drug.
Thiazides cross the placental barrier and appear in cord blood. There is a risk of fetal or neonatal jaundice, thrombocytopenia, and possibly other adverse reactions that have occurred in adults.
Hypotension - Volume Depleted Patients: In patients who are intravascularly volume-depleted (e.g those treated with diuretics) symptomatic hypotension may occur after initiation of therapy and this condition should be corrected prior to administration.
Impaired Hepatic Function: It is not recommended for patients with hepatic impairment who require titration with losartan. The lower starting dose of losartan recommended for use in patients with hepatic impairment cannot be given using losartan potassium + Hydrochlorothiazide. Thiazides should be used with caution in patients with impaired hepatic function or progressive liver disease, since minor alterations of fluid and electrolyte imbalance may precipitate hepatic coma.
Hypersensitivity reactions: Hypersensitivity reactions to hydrochlorothiazide may occur in patients with or without history of allergy or bronchial asthma, but are more likely in patients with such a history.
Systemic Lupus Erythematosus: Thiazide diuretics have been reported to cause exacerbation or activation of systemic lupus erythematosus.
Lithium Interaction: Lithium should not be generally given with thiazide.
Co-Normoten: Hepatic and Renal Impairment: Losartan Potassium and Hydrochlorothiazide is not recommended for patients with hepatic impairment or severe renal impairment.
As a consequence of inhibiting the renin-angiotensin system, changes in renal function including renal failure have been reported. These changes in renal function may be reversible upon discontinuation of therapy.
Other medications that affect the renin-angiotensin system including Losartan Potassium and Hydrochlorothiazide may increase blood urea and serum creatinine in patients with bilateral renal artery Stenosis of the artery to a solitary kidney. Similar effects have been reported with Losartan; these changes in renal function may be reversible upon discontinuation of therapy.
Hypotension and Electrolyte/Fluid Imbalance: In patients who are intravenously volume-depleted (e.g. those treated with high dose diuretics), symptomatic hypotension may occur. These conditions should be corrected prior to administration of Losartan Potassium and Hydrochlorothiazide, or a lower starting dose should be used. Periodic determination of serum electrolyte should be performed at appropriate intervals as in any patients receiving diuretics.
Metabolic and Endocrine Effects: Thiazide therapy may impair glucose tolerance. Dosage adjustment of anti diabetic agents including insulin may be required.
Thiazides may decrease urinary calcium excretions and may cause intermittent and slight elevation of serum calcium, marked hypercalcemia may be evidence of hidden hyperparathyroidism. Thiazides should be discontinued before carrying out tests for parathyroid function.
Increase in cholesterol and triglycerides levels may be associated with thiazides diuretic therapy. Thiazide therapy may precipitate hyperuricemia and/or gout in certain patients. Because Losartan decreases uric acid. Losartan in combination with Hydrochlorothiazide attenuates the diuretic-induced hyperuricemia.
Other: In patients receiving thiazides, sensitivity reactions may occur with or without a history of allergy of bronchial asthma. Exacerbation or activation of lupus erythematosus has been reported with the use of thiazides.
Use in Children: Safety and efficacy in children has not been established.
Pregnancy: Co-Normoten: When pregnancy is detected, Losartan Poatassium and Hydrochlorothiazide shoud be discontinued as soon as possible. Not to be used in pregnancy as teratogenicity has been shown in experimental animals.
Thiazides cross the placental barrier and appear in cord blood. The routine use of diuretics in otherwise healthy pregnant is not recommended and exposes mother and fetus to unnecessary hazard including fetal or neonatal jaundice, thrombocytopenia and possibly other adverse reactions which have occurred in adult. Diuretics do not prevent development of toxemia of pregnancy and there is no satisfactory evidence that they are useful in the treatment of toxemia.
Women of child bearing age should ensure adequate contraception.
Co-Normoten DS: Female patients of childbearing age should be told about the consequences of second and third-trimester exposure to drugs that act on the renin-angiotensin system, and they should be told that these consequences does not appear to have resulted from intrauterine drug exposure that has been limited to the first trimester. These patients should be asked to report pregnancies to their physician as soon as possible.
Fixed dose of Losartan Potassium and Hydrochlorothiazide is well tolerated. Adverse events have been limited to those that were reported previously with Losartan Potassium and/or Hydrochlorothiazide. Adverse events are generally mild and transient in nature and do not require discontinuation of therapy. The most commonly reported adverse effects are abdominal pain, edema, swelling, palpitation, back pain, dizziness, cough, sinusitis, upper respiratory tract infection, rash.
Patient to seek medical attention immediately at the first sign if any adverse dug reaction shall appear.
No side effects peculiar to this combination have been observed. Side effects have been limited to those that were reported previously with Losartan Potassium and /or Hydrochlorothiazide.
Losartan is generally well tolerated in a controlled clinical trial in hypertensive patients with left ventricular hypertrophy. The most common drug-related side-effects were dizziness, asthenia/fatigue and vertigo. The following adverse reactions have been reported: Hypersensitivity:
Anaphylactic reactions, angioedema including swelling of the larynx and glottis causing airway obstruction and/or swelling of the face, lips, pharynx, and/or tongue have been reported rarely in patients treated with losartan; some of these patients previously experienced angioedema with other drugs including ACE inhibitors. Vasculitis, including Henoch-Schonlein purpura, has been reported rarely.
Hepatitis (reported rarely), diarrhea, liver function abnormalities.
Urticaria, pruritus, rash.
Hydrochlorothiazide side effects: Body as a whole:
pancreatitis, jaundice (intrahepatic cholestatic jaundice) sialadenitis, cramping, gastric irritations.
aplastic anemia, agranulocytosis, leukopenia, hemolytic anemia, thrombocytopenia.
purpura, photosensitivity, urticaria, necrotizing angiitis (vasculitis and cutaneous vasculitis), fever, respiratory distress including pneumonitis and pulmonary edema.
hyperglycemia, glycosuria, hyperuricemia.
renal failure, renal dysfunction, interstitial nephritis.
erythema multiforme including Stevens-Johnson syndrome, exfoliative dermatitis including toxicepiderma necrolysis.
transient blurred vision; xanthopsia.
Patient to seek medical attention immediately at the first sign if any adverse drug reaction shall appear.
Losartan Potassium does not affect the pharmaceutics or pharmacodynamic of a single dose of Warfarin and also intravenous or oral Digoxin. Coadministration of Losartan Potassium and cimetidine leads to an increase of about 18% in AUC of Losartan Potassium but does not affect the pharmacokinetics of its active metabolite. There is no pharmacokinetic interaction between Losartan Potassium and Hydrochlorothiazide.
When administered concomitantly the drugs, which may interact are: Alcohol, barbiturates or narcotics, antidiabetic drugs, other antihypertensive drugs, cholestyramine and colestipol resins, corticosteroids, pressor amines (e.g. norepinephrine) skeletal muscle relaxants, lithium, Non-Steroidal Anti-inflammatory Drugs (NSAIDS).
Store at temperatures not exceeding 30°C.
C09DA01 - losartan and diuretics ; Belongs to the class of angiotensin II receptor blockers (ARBs) in combination with diuretics. Used in the treatment of cardiovascular disease.
Co-Normoten: Tab 50 mg/12.5 mg (pinkish red coloured, round, biconvex, film coated tablet) x 100's.
Co-Normoten DS: FC tab 100 mg/25 mg (yellow colored, oval shaped, biconvex film coated tablets with breakline on both sides) x 30's.