Ireland-based drugmaker Warner Chilcott is adding a line or score to its Doryx (doxycycline hyclate) tablet. This does not affect the chemical composition of the antibiotic used to treat severe acne. Rather, it makes it easier for patients to divide and take the tablets in thirds, according to the company’s citizen petition filed with FDA on 23 September 2011.

If FDA accepts Warner Chilcott’s argument, generic drugmakers seeking to make generics of doxycycline hyclate may be forced by FDA to rework their own versions, causing a delay in approval. This may be the first time such a manoeuvre will have delayed generics rivals, according to The Wall Street Journal.

The Doryx tablets previously had only one score, however, Warner Chilcott’s recent addition of a second score to its tablet means that generic versions must now also have the same number of scores.

In its citizen petition, Warner Chilcott said that approving generics with only one score ‘would raise public health concerns’. The drugmaker argued that doctors might instruct patients to divide the Doryx tablet into thirds, but a generic version with just one score would make it difficult to get the right dose, leading ‘to patient confusion and sub-optimal dosing’.

This tactic from Warner Chilcott follows the release in August 2011 of new draft guidance from FDA on scoring tablets. The FDA guideline states ‘consistent scoring ensures that the patient is able to adjust the dose, by splitting the tablet, in the same manner as the reference listed drug [brand-name drug]’. ‘This enables the patient to switch between products made by different manufacturers without encountering problems related to the dose. In addition, consistent scoring ensures that neither the generic product nor the brand-name drug has an advantage in the marketplace because one is scored and one is not.’

There is much at stake. More than 383,000 patients in the US alone take Doryx. In 2010, the drug generated US$172 million in sales, or around 6% of Warner Chilcott's total revenue for 2010, according to data from Wolters Kluwer Pharma Solutions.

The citizen petition from Warner Chilcott comes amid ongoing patent litigation. On 22 September 2011, the company announced that it had been granted a preliminary injunction against generics giant Mylan by the US District Court in New Jersey, USA, preventing Mylan from launching a generic version of Doryx. Warner Chilcott alleges Mylan is guilty of infringing on its ‘161 patent’ for Doryx which expires in 2022.