FDA is concerned that differences in the physical characteristics of medicines, e.g. size and shape of the tablet or capsule, ‘may affect patient compliance and acceptability of medication regimens or could lead to medication errors’.

The agency estimates that as many as 40% of Americans may have difficulty swallowing tablets and capsules. Of those who experience difficulty swallowing medications, less than a quarter discuss the problem with a healthcare professional, 8% admit to skipping a dose of prescribed medication, and 4% have discontinued therapy because the tablets and/or capsules were difficult to swallow. Size is the main reason cited for the difficulty in swallowing.

Size
FDA has therefore set limits on how much generics should vary from originators. For example, for tablets smaller than 17 mm, generics should be no more than 20% larger in any single dimension and no more than 40% larger in overall volume to the originator. For tablets equal to or greater than 17 mm, generics should be no larger than the originator in volume or in any single dimension.

The agency does state that ‘flexibility may be given for products that are 8 mm or smaller in their largest dimension’, but ‘efforts should be made to develop tablets and capsules that are of a similar size and shape’ to the originator. They also recommend that the largest dimension of a tablet or capsule should not exceed 22 mm and that capsules should not exceed a standard 00 size to make them easier to swallow.

Shape
In addition to the size recommendations, FDA recommends manufacturing tablets and capsules that have a similar shape or have a shape that has been found to be easier to swallow compared with the shape of the originator.

Other physical attributes
Other physical attributes of tablets and capsules that FDA believes should be considered to make swallowing easier include tablet coating, weight, surface area, disintegration time and propensity for swelling.

Size, shape and other physical attributes of generic tablets and capsules
www.fda.gov/ucm/groups/fdagov-public/@fdagov-drugs-gen/documents/document/ucm377938.pdf

The final guidance replaces a draft version that was issued in December 2013 [1]. The guidance will apply to all new abbreviated new drug applications (ANDAs) for generics and their supplements for additional strengths, but will not be applied retrospectively to already approved generics. However, FDA does add a caveat that this may change ‘if the agency determines that an approved product should be modified because the size or shape of a product poses a risk to public health’.

FDA is also carrying out a survey of pharmacists and patients to gain more information on how changes in the physical characteristics of generics pills affect patients’ perceptions [2].

Related article
FDA outlines details of surveys into physical differences in generics

References
1. GaBI Online - Generics and Biosimilars Initiative. US guidelines for generics [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2015 Aug 14]. Available from: www.gabionline.net/Guidelines/US-guidelines-for-generics
2. GaBI Online - Generics and Biosimilars Initiative. FDA to carry out survey into affect of generics shape, colour, size [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2015 Aug 14]. Available from: www.gabionline.net/Guidelines/FDA-to-carry-out-survey-into-affect-of-generics-shape-colour-size

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