A ‘generic medication’ is a medicinal compound traded under its non-proprietary, approved ‘trade’ name, or is marketed with a different brand (proprietary) trade name [2]. Such drugs may be produced by a different pharmaceutical company, other than the original R & D manufacturer, claiming bioequivalence when compared with the originator compound upon which they are based [2]. The generic alternative medication aims to capitalize on the success of the original R & D medication, towards the end of its patent protection, essentially ‘copying’ it with a similar formulation, with identical active ingredient, but potentially having a different excipient or salt content. Generics can be produced and marketed much cheaper, at about 20%–90% of the price of the originator [3]. Some R & D companies also market their products, adopting a different ‘proprietary’ trade name, to suggest a generic alternative, as a way of maintaining market share [4].

Generics, unlike the originator medication, which required extensive animal and human clinical trials, only need to show bioequivalence in a relatively small number of health volunteers [5, 6], possibly <30 people but definitely <100. The efficacy and safety, of the generic medication, must respect defined boundaries with an identical amount of active ingredient(s), provided as an identical dosage, using a similar route of administration, with comparable drug availability [7]. Bioequivalence testing, on the ≤100 healthy volunteers, compares the generic and R & D medication, adopting a randomized sequence and appropriate washout period between them [8]. Both before and after such administration, plasma concentrations are evaluated at regular, predetermined intervals. The identical active moiety, in both the generic and originator parent compound, must be compared in the same individual, making each subject his/her own control [6].

Bioequivalence is determined by peak plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC), demonstrating comparable rate and extent of absorption of the active ingredient [7, 9]. The US Food and Drug Administration (FDA) accepts bioequivalence if the ratio of AUC_generic to AUC_branded and C_{max generic} to C_{max branded}, for the average of the sample of participants lies between 0.80%–1.25% of the originator medication, at the 90% confidence level for AUC and Cmax [7, 9]. This implies that the generic medication, shown to be 80% bioequivalent, is comparable to that which was 125% bioequivalent, despite >56% variation between the two results. Different generics are not directly compared against each other, ‘bioequivalence’ has been established with the originator medication.

Conflict of interest
The author of the research paper [1] declared that there was no conflict of interest.

Abstracted by Professor Roy G Beran, Neurology Department, Liverpool Hospital, Liverpool, Australia.

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References
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