Bioadhesive gels

Shin SC, Bum JP, and Choi JS (2000) Enhanced bioavailability by buccal administration of triamcinolone acetonide from the bioadhesive gels in rabbits. Int. J. Pharm. 209 37—43. 

Bioadhesive Drug Delivery Systems 22.7.2.1 Bioadhesive Gels... 

Miphil (Columbia Laboratories Inc., Livingston, NJ, USA), a marketed bioadhesive gel based on polycarbophil and capable of reducing vaginal pH, has been used in combination with oral tinidazol for the treatment of bacterial vaginosis. In a multicenter, randomized, investigator-blinded, controlled clinical trial, the combination of the antibiotic with the... 

Bioadhesive gels were also reported in the literature as vehicles for microparticulate formulations. Such formulations will be described in Section 22.7.2.5. 

Amaral, E., et al. 1999. Study of the vaginal tolerance to Acidform, acid-buffering bioadhesive gel. Contraception 60 361. 

Dry vagina the bioadhesive gel can hydrate vaginal tissue for 3-4 days after a single application. Tissue hydration is caused by an increased blood flow, thus increasing transudation of vaginal fluid though the intercellular channels of the vaginal epithelium. 

Spermicide-antiviral the polymer appears to be an effective delivery system for the spermicidal/antiviral agent nonoxynol-9. By its ability to adhere to vaginal tissue while retaining nonoxynol-9 in its gel structure, it is an excellent extended effect spermicide. As an antiviral, nonoxynol-9 can only kill free HIV and is not noticeably active when the virus is within a lymphocyte. In contrast, the bioadhesive gel containing nonoxynol-9 attaches to lymphocytes and maintains sufficient contact time to allow the nonoxynol-9 surfactant to disrupt the cell wall, thus eliminating the lymphocyte and killing the vims within. This suggests that the polymer may be useful in the prophylaxis of AIDS and the treatment of other sexually transmitted diseases. 

Describe how bioadhesive gels enhance the vaginal absorption of drugs. 

Diffusion, dissolution, microenvironmental pH, bioadhesion, gel development in hydrophilic matrices, drag release processes, surface roughness in tablets and pellets... 

Vonarx, V. Eleouet, S. Carre, J. loss, R Gouyette, A. Leray, A.M. Merle, C. Lajat, Y. Patrice, T. Potential efficacy of a delta 5-aminolevulinic acid bioadhesive gel formulation for the photodynamic treatment of lesions of the gastrointestinal tract in mice. J. Pharm. Pharm. 1997,49 (7), 652-656. 

Andrews, G. P., Gorman, S. R, and Jones, D. S. (2005). Rheological characterization of primary and binary interactive bioadhesive gels composed of cellulose derivatives designed as ophthalmic viscosurgical devices, Biomatenal 26, 571-580. 

Bioadhesion gels generally employ the same mechanism as involves ointments and the tapes to hold them in place. However, the adhesion mechanism of ointments is different from the adsorption mechanism of bioadhesion gels. In the cases of the skin, the interface between the... 

Chapter 4 Section 5 Bioadhesion Gels and Their Applications... 

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