Intravaginal rings

Avoid systemic (parenteral, oral, TD) vaginal tablet, cream, intravaginal ring Estradiol 25 meg vaginal tablets (insert one PV daily x 14 days, then one PV twice weekly)... 

Is a local or systemic effect required This will influence, for example, the choice between a traditional dosage form, such as a semisolid cream or gel, and a system that promotes increased intravaginal residence, with a concomitant increased possibility of absorption across vaginal epithelium, for example, from intravaginal ring (IVR) systems or systems utilizing a bioadhesive polymer component. 

Intravaginal Rings Currently being Marketed or Developed... 

Malcolm, R.K. 2003. The intravaginal ring. In Modified-release drug delivery technology, eds. M.J. Rathbone, J. Hadgraft, and M.S. Roberts. New York Marcel Dekker, chap. 64. 

Sandwich or reservoir-type intravaginal ring (IVR) devices have been developed to obtain zero-order drug release. 

Mishell, D. R., Jr., Lumkin, M., and Jackanicz, T. (1975), Initial clinical studies of intravaginal rings containing norethindrone and norgestrel, Contraception, 12, 253-260. 

Malcolm, K., Woolfson, D., Russell, J.,Tallon,P.,McAuley, L., and Craig, D. (2003), Influence of silicone elastomer solubility and diffusivity on the in vitro release of drugs from intravaginal rings, J. Controlled Release, 90, 217-225. 

K. Gupta, S. Pearce, A. Poursaid, H. Ahyar, P. Tresco, M. Mitchnik, P. Kiser, Polyurethane intravaginal ring for controlled delivery of dapivirine, a noimucleoside reverse transcriptase inhibitor of HIV-1, J. Pharm. Sci. 97 (10) (2008) 4228-4239. 

Polyurethane intravaginal rings Dapivirine and tenofovir Suitable delivery system for the sustained delivery of drugs with contrasting hydrophilicity Tenofovir showed sustained release whereas dapivirine exhibited linear release over time [26]... 

T.J. Johnson, K.M. Gupta, J. Fabian, T.H. Albright, PF. Kiser, Segmented polyurethane intravaginal rings for the sustained combined delivery of antiretroviral agents dapivirine and tenofovir, Eur. J. Pharm. Sci. 39 (2010) 203-212. 

Certain polymers, e.g., silicone may be formulated into implantable dosage forms, e.g., intravaginal rings or as medicated medical devices. Processing of these systems involves crosslinking of polydimethylsiloxane at an elevated temperature in the presence of a catalyst. Medicated intravaginal silicone drug delivery systems has been used clinically for several decades for contraceptive purposes and for the synchronisation of oestrus in farm animals (a.47, a.82). However more recently these systems have been reformulated for the treatment of symptoms of the menopause (a.82), for the controlled delivery of oxybutinin (for the treatment of urinary incontinence) (a.83) and for the delivery of nonoxynol-9 to prevent transmission of sexually transmitted diseases (a.84). 

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