Quay Pharma, a UK provider of contract pharmaceutical r&d and clinical trials manufacturing, has with a US client developed a novel vaginal tablet that forms a gel containing a potent microbiocide that blocks HIV from entering the bloodstream.
Of the 16,000 people worldwide contracting HIV every day, the majority are infected by unprotected sex, with the greatest incidence being in sub-Saharan Africa and India. While work continues into the development of new drugs and vaccines, the use of microbiocides formulated as gels is currently considered the best chance yet of controlling the spread of AIDS; a recent finding suggested that a gel, applied inside the vagina, may reduce the chances of women contracting HIV by a third.
Quay’s client, a large private non-profit organisation, has a long established research programme into methods of reducing the incidence of HIV sexual transmission. Following the screening of a large number of pharmaceutical acceptable compounds, the company found one that had good in vitro activity against HIV and pronounced in vivo efficacy against HIV challenge vaginally in animal models.
For the compound to be evaluated the organisation needed an effective means for its intra-vaginal administration. A variety of different methods were tried unsuccessfully; many of the excipients used in the formation of creams and gels proved an irritant to the sensitive vaginal mucosae or did not provide entire mucosae coverage.
Quay was asked to develop a novel vaginal tablet that, once administered, would be able to gel very quickly to produce a clear, non-irritant, barrier layer that was undetectable by the male partner during intercourse.
The requirement was for the tablet to gel within less than two minutes in 2ml of simulated vaginal fluid and to develop muco-adherent properties within five minutes, and to ensure that the gel remained in the vagina during intercourse. Additionally, the gel formed from the tablet needed to have an acidic pH of 3–5 and remain acidic (pH<6) when mixed in vitro with a volume of semen typical of a human ejaculate.
Using its expertise in tablet formulation development, many possible formulations were proposed and tried out by Quay Pharma, using various acceptable and non-irritant swellable polymers. The formulation finally selected was the one that could be compressed most easily into vaginal tablets.
Patent filings have now taken place for the selected tablet, which will now be assessed in extensive clinical trials.
‘We believe this development will be a very significant milestone in the battle to protect people against HIV/AIDS infection and will be especially welcomed in developing countries as an inexpensive and culturally acceptable method of protection,’ commented Mike Rubinstein, Quay Pharma’s chief executive.