Twenty-three anti-hypertensive drugs, having countrywide market, have been found complying with relevant pharmacopoeial standards except some changes in dissolution and pricing of drugs, according to a study conducted by a consumer rights organisation, the Consumer Education and Research Centre (CERC).

The Ahmedabad-based CERC has cleared 23 brands of anti-hypertensive tablets based on five molecules as complying various pharmacopoeial standards.

The tests were conducted on single molecule and combination tablets of anti-hypertensive drugs, which are preferred and prescribed by doctors, for testing. The molecules tested were atenolol beta-blocker and the ACE inhibitors enalapril and lisinopril. The combination drugs selected by the centre for testing were enalapril maleate with hydrochlorothiazide, an ACE inhibitor and atenolol with chlorthalidone, a beta blocker with calcium channel blocker.

The atenolol tablets, which had 25 mg strength, were Atenova, Hipres, Betacard, Atepark, Tenormin, Tensicard, Atenex and Atecard. The enalapril maleate tablets of 2.5 mg were Envas, Enam, Enapril and Enace. The lisinopril 2.5 mg tablets were Listril, Lipril, Cipril and Zestril. The combination products were Normace-D, Enapril-HT, Enace-D and Envas H in the enalapril maleate with hydrochlorothiazide category and it was Tenoric-50, Tenoclor-50 and Atecard-D in the combination of atenolol with chlorthalidone.

All the drugs were tested as per their respective pharmacopoeia and the combination product of atenolol and chlorthalidone was marked as British Pharmacopoeia (BP) but was tested as per the US Pharmacopoeia to provide more information to consumers, informed the organisation. The tablets were tested for four basic parameters, identification, assay, uniformity of weight and disintegration. The combination product atenolol with chlorthalidone was also tested for dissolution as per the US Pharmacopoeia.

While all the brands passed the tests, Atecard-D, manufactured by Dabur failed to conform to the dissolution test mentioned in the US Pharmacopoeia. Less dissolution means that the effect will be slower and the absorption of the drug in the blood will be less. Except Atecard-D, other brands marked BP but tested as per USP, passed all the tests, including the dissolution test. The dissolution test measures the actual release of the drug from the tablet, which is an essential step in drug availability of the body.

The other experiments conducted includes test for assay, to find out the actual amount of active ingredient in the tablet and whether it is the same as what is labelled, test for uniformity of weight to check the individual variation of the weight from the average weight of the dosage unit, disintegration test to break down into small particles or disintegrate so that it is ready for absorption within a specific time period and the test for uniformity of content test to determine whether the actual amount of active ingredient is present in a single dose.

The test on prices of the drugs showed that all the brands complied with the standards, a major criterion for preferring one brand to another is the price. Zestril (2.5 mg) manufactured by Astra Zeneca Pharma was found costlier than the other brands of Lisinopril.

As part of its policy, the centre has informed the test results to the manufacturers for their views and comments with adequate arrangements so that the companies will receive results of their own product only.