|Carrageenan-based vaginal suppositories--Courtesy of Pharmaceutics|
Penn State University researchers have designed a novel suppository for HIV antiretroviral delivery using the seaweed extract carrageenan. Almost half of the antiretroviral drug tenofovir diffused out of the delivery mechanism within the first two hours in an in vitro study testing the product in water, vaginal simulant fluid and semen simulant fluid.
So far microbicide development has been hampered by drug delivery issues that lower absorption of the active ingredient. There are no commercial anti-HIV microbicides on the market. Could the carrageenan-based suppository become the first?
The team chose to use carrageenan because it is not susceptible to animal-based infections, is a vegetarian-friendly component and tolerates heat well (an issue in many emerging markets), according to in-PharmaTechnologist. Another key feature is the suppository's semisoft firmness. Liquid-based gels leak, while hard tablets absorb liquids via osmosis.
The product's rapid drug release is critical and should improve compliance. The authors say that the delivery mechanism also releases the drug slowly over 24 hours following the initial rapid release.
The innovation marks a new, albeit experimental, formulation for tenofovir, currently marketed for oral use by pharma company Gilead Sciences ($GILD) under the brand name Viread. Carrageenan also has applications in other microbicides against genital herpes and the human papillomavirus, as well as wound dressings, according to the study.
Unfortunately, the carrageenan suppositories do not break down during sex, meaning the product cannot be used secretly. The researchers say that efforts to develop eroding suppositories are under way.