Indication For management of Hypertension
Mechanism of Action

Olmesartan is a selective and competitive angiotensin II Type 1 (AT1) receptor antagonist that blocks the vasoconstrictor and aldosterone-secreting effects of angiotensin II. As a result, Olmesartan relaxes blood vessels, hence lowering BP and increases blood supply and oxygen to the heart.

Chlorthalidoneis an oral, long acting antihypertensive/diuretic. It is a mono-sulfamyl diuretic that acts by enhancing the excretion of sodium and chloride ions, and water by interfering with the transport of sodium ions across the renal tubular epithelium. Their primary site of action appears to be at the cortical diluting segment in the nephron of the loop of Henle.



Absorption: Bioavailability: Approx. 26%. Time to peak plasma concentration: Approx. 1-2 hr.

Distribution: Volume of distribution: 17 L. Plasma protein binding: ≤99%.

Metabolism: Olmesartan medoxomil undergoes ester hydrolysis in the GI tract to active form Olmesartan.

Excretion: Via faeces (50-65%) and urine (35-50%) both as Olmesartan. Terminal half-life: Approx. 10-15 hr.


Onset: 2 hr

Duration: 48-72 hr.

Absorption: Erratic absorption from the GI tract (oral).

Distribution: Binds to red blood cells; crosses the placenta and enters breast milk.

Protein-binding: Weak

Excretion: Urine (as unchanged drug); 40-60 hr (elimination half-life).

Side effects


Potentially Fatal: Acute renal failure.

May cause sprue-like enteropathy (Symptoms: Severe, chronic diarrhoea with substantial wt. loss). Dizziness, headache, abdominal pain, dyspepsia, diarrhoea, gastroenteritis, nausea, bronchitis, pharyngitis, rhinitis, arthritis, back pain, skeletal pain, fatigue, flu-like symptoms, angioedema, peripheral oedema, haematuria, UTI, hyperkalaemia, hypertriglyceridemia, hyperuricaemia, hyperglycaemia, elevated liver enzymes.


Potentially Fatal: Rare. Severe hyponatraemia and idiosyncratic hypersensitivity.

Dry mouth, thirst, weakness, lethargy, drowsiness, restlessness, seizures, oliguria, hypotension, fatigue, muscle cramps and GI disturbances, nausea, vomiting, constipation, diarrhoea, anorexia. Diabetes and gout may be precipitated. Impotence. Raised blood levels of glucose, urates, lipids and calcium. Reduced levels of K and magnesium. Raised CPK levels.



Patients with aortic or mitral valve stenosis, renal artery stenosis; at risk for hypotension (e.g. patients with volume or salt depletion); history of angioedema; at risk for hyperkalaemia (e.g. patients w/ DM). Severe renal and hepatic impairment. Lactation. Monitoring Parameters Monitor BP, serum creatinine and K levels periodically.


Existing fluid and electrolyte disturbances, hepatic cirrhosis, severe heart failure, hyperuricaemia, mild to moderate renal impairment. Elderly. Monitor fluid and electrolyte balance. Kidney or liver disease; diabetes; gout; hyperlipidaemia and ventricular extra systoles.



Adult: Initial: 10-20 mg once daily may then be increased up to max 40 mg once daily if needed.

Child: 6-16 yr. 35 kg: 10 mg once daily; ≥35 kg: 20 mg once daily. Doses may be doubled once if necessary after 2 wk.

Elderly: No dosage adjustment needed.

Renal impairment: Mild to moderate (Circle: 20-60 mL/min): Max: 20 mg once daily.

Hepatic impairment:

Moderate: Initial: 10 mg once daily may increase up to max 20 mg once daily.