Gel-Forming Vaginal Tablet Helps To Control Spread Of AIDS
LONDON, 23 February 2012-In association with its client, Quay Pharma has developed a novel vaginal tablet which rapidly and completely forms a gel containing a potent microbiocide that blocks HIV from entering the bloodstream.
Of the 16,000 people around the world 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. A key benefit is that it offers an opportunity for women to protect themselves against infection where their partners are unwilling to use any form of protection.
Quay’s client, a large private non-profit corporation in the United States, 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 a compound that had good in-vitro activity against HIV and also had pronounced in-vivo efficacy against HIV challenge vaginally in animal models.
In order for the compound to be evaluated in clinical trials Quay’s client needed an effective means for its intra-vaginal administration. A variety of different methods were tried unsuccessfully, with particular problems being that 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 and therefore protection.
Quay was approached 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 rapidly and completely gel within less than two minutes in 2mls of simulated vaginal fluid and to develop mucoadherent 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 Quay’s expertise in tablet formulation development, many possible formulations were proposed and tried out experimentally, using various acceptable and non-irritant swellable polymers. Ensuring that a complete gel was formed quickly and completely was made even more difficult by the requirement that the gel had to be formed with only very small amounts of water present (2mls). The formulation finally selected and progressed was the one that could be compressed most easily into vaginal tablets.
Patent filings have now taken place for the selected tablet, which is planned to be assessed in extensive clinical trials.
"This has been a very exciting and challenging project and we are very proud to have made such a significant contribution," comments Mike Rubinstein, Quay Pharma’s Chief Executive.
"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."
Bob Bushby/John Atkin
Nielsen McAllister PR Limited
Tel: 44 1332 293939
Fax: 44 1332 382202
Tel: 44 151 203 9800
Fax: 44 1244 281 283
Posted: February 2012