# E-DRUG: Re: Bioequivalence of generics and brand name drugs (contd) **URL:** \ **Category:** e-drug\ **Created:** [September 24, 1998, 8:45pm UTC](https://talk.edrugplus.org/t/e-drug-re-bioequivalence-of-generics-and-brand-name-drugs-contd/3537 "1998-09-24T20:45:39Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![kirsten.myhr1](https://avatars.discourse-cdn.com/v4/letter/k/c37758/32.png) [@kirsten.myhr1](https://talk.edrugplus.org/u/kirsten.myhr1)\ **Post date:** [September 24, 1998, 8:45pm UTC](https://talk.edrugplus.org/t/e-drug-re-bioequivalence-of-generics-and-brand-name-drugs-contd/3537/1 "1998-09-24T20:45:39Z")
E-drug: Re: Bioequivalence of generics and brand name drugs (contd) ---------------------------------------------------------- In addition to the statement by FDA mentioned by Joel Lexchin, an article from Drug and Therapeutics Bulletin (1997;35(2):9-11) called Generic medicines - can quality be assured? is worth mentioning. In countries with regulatory measures that ensures that licensed medicines are safe, effective and of adequate quality patients should be confident that branded and generic versions with the same ingredient in the same strength and in the same dosage form should provide the same therapeutic response. Manufacturers of generic equivalents are required to show 'essential similarity' to the first branded drug, i.e. that the product is of the same pharmaceutical form and has the same quality and quantity of active ingredient. A debate has been going on in EU concerning a definition of 'essentially similar'. There is also some differences in opinion as to whether tablets and capsules are 'essentially similar'. The manufacturer is also required to show that the preparation is bioequivalent (absorbed at the same rate and to the same extent) as the first brand. Typically, tests of bioequivalence are done in groups of 12 to 24 young, healthy volunteers. Products are tested in a crossover design and usually in single-dose studies. Now all this has certain limitations of course and as mentioned in my note to Joel's most recent posting, regulatory authorities may have different limits for what is regarded as 'essentially similar' e.g. an acceptable deviation of + - 20% in plasma levels. The day after posting Joel's question, I was reading the Pharmaceutical Journal and came across an advertisement with the heading: Epilepsy: An exception to the generic rule. This advert - for sodium valproate from Sanofi Winthrop provides references for a claim that switching should not occur: (please note that this is an advert in favour of one drug) Crawford P et al. Generic prescribing for epilepsy. Is it safe? Seizure 1996;5(1):1-5 Phillips G. Prescribing of anticonvulsant medicine (letter). Pharmaceutical Journal 1996;257:658 Phillips G. Prescribing in epilepsy (letter). Pharmaceutical Journal 1997;258:18 Chappel B, Crawford P. Generic prescribing (letter). Pharmaceutical Journal 1997;258:446 Chappel B. The threat of medicine substitution - the patient's viewpoint Not What the Doctor Ordered. Queen's University, Belfast 1993:71-80 Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology Assessment: Generic substitution for anti-epileptic medication. Neurology 1990;40:1641-3 New Zealand Medical Assosiation: A warning re anticonvulsant drugs. New Zealand Medical Association Newsletter in New Zealand Medicine 23rd March 1994:10 Kirsten Kirsten Myhr Bygdoy alle 58B 0265 Oslo, Norway myhr@online.no -- Send mail for the `E-Drug' conference to `e-drug@usa.healthnet.org'. Mail administrative requests to `majordomo@usa.healthnet.org'. For additional assistance, send mail to: `owner-e-drug@usa.healthnet.org'.