20 mg and 40 mg tablets
Olmetec Plus (Schering-Plough)
20 mg olmesartan medoxomil/12.5 mg hydrochlorothiazide tablets
40 mg olmesartan medoxomil/12.5 mg hydrochlorothiazide tablets
40 mg olmesartan medoxomil/25 mg hydrochlorothiazide tablets
Approved indication: hypertension
Australian Medicines Handbook section 6.4.5
Olmesartan is the sixth angiotensin receptor antagonist to be marketed in Australia. Like the other members of its class it blocks the binding of angiotensin II to the angiotensin (AT1) receptor (see 'Angiotensin receptor antagonists for the treatment of hypertension', Aust Prescr 1998;21:95-7).
As olmesartan medoxomil is a prodrug it has to be converted to active olmesartan. This metabolism occurs during absorption. The bioavailability is 26%, but this is unaffected by food. Up to half of the absorbed drug is excreted in the urine. Renal and hepatic impairment will increase concentrations of olmesartan.
The efficacy of the drug has been shown in several placebo-controlled trials. Approximately 70% of patients with hypertension will respond. The mean reductions in ambulatory blood pressures with a daily dose of 20 mg olmesartan are 11 mmHg diastolic and 14 mmHg systolic.1 The maximum effect of olmesartan occurs by the eighth week of treatment.
Olmesartan has been compared with other antihypertensive drugs. Olmesartan 20 mg had a greater effect on blood pressure than 50 mg losartan, 150 mg irbesartan and 8 mg candesartan.2
When combined with hydrochlorothiazide the efficacy of olmesartan is similar to that of atenolol and hydrochlorothiazide. The combination product should only be used when the patient's hypertension has not been controlled by olmesartan or hydrochlorothiazide alone.
The most common adverse effect of olmesartan is dizziness. Cough does not appear to be a major problem, but angioedema has been reported. Like other angiotensin receptor antagonists and ACE inhibitors caution is needed when prescribing for patients who may have renal impairment or be volume depleted by diuretics. Similarly, taking a non-steroidal anti-inflammatory drug with olmesartan could cause renal failure.
Hypertension is a chronic disease, but most trials of efficacy only last a few months. Although it may have a greater effect on blood pressure, the long-term effects of olmesartan are uncertain. As currently available angiotensin receptor antagonists have been more widely used and as some have also been approved for heart failure and diabetic renal disease, olmesartan should probably not become the first choice until it has more outcome data.
The Transparency Score ( ) is explained in New drugs: transparency', Vol 37 No 1, Aust Prescr 2014;37:27.
- Neutel JM. Clinical studies of CS-866, the newest angiotensin II receptor antagonist. Am J Cardiol 2001;87(Suppl):37C-43C.
- Stumpe KO. Olmesartan compared with other angiotensin II receptor antagonists: head-to-head trials. Clin Ther 2004;26(Suppl A):A33-A37.