An intravaginal ring made from the plastic ethyl-vinyl acetate copolymer (EVA) and loaded with the two drugs dapivirine and maraviroc – already found to enhance each other’s potency – can deliver therapeutic levels of both drugs for as long as a month, according to test-tube studies. Fifteen days after being placed in a water/alcohol mixture, the ring was delivering half a gram of dapivirine and a gram of maraviroc per day.
The tablet is ‘bioadhesive’ – this means the voluminous gel gets the drug delivered to all the mucous surfaces needed and then dissolves away. It also binds the drug to the mucous membranes, concentrating it at the surfaces needed and guaranteeing a consistent level of drug over 8-12 hours.
The film is made of a thin polyvinyl alcohol polymer, a water-soluble synthetic plastic used in multiple consumer and biomedical products, including contraceptive films, contact lens solutions and mouthwash strips.