Drug release penetration enhancers

Yeh, P.Y., Berenson, M.M., Samowitz, W.S., Kopeckova, P, and Kopecek, J. (1995). Site-specific drug-delivery and penetration enhancement in the gastrointestinal-tract. J. Control. Release, 36, 109-124. 

Figure 8 (A) In vitro permeability of candidate drug molecules in the presence of synergistic combinations of penetration enhancers (SCOPE) formulations. Open circles indicate passive skin permeability and closed circles indicate skin permeability in the presence of SCOPE formulations as a function of the molecular weight of the solute. (B) In vivo delivery of leuprolide acetate, a synthetic analogue of LHRH in hairless rat model, y-axis shows blood plasma concentration of leuprolide acetate as a function of time for control formulation (open circles) and SCOPE formulation (closed circles). Abbreviation-. LHRH, luteinizing hormone-releasing hormone.

Ghafourian, T., et al. 2004. The effect of penetration enhancers on drug delivery through skin A QSAR study. J Control Release 99 113. 

Conventional systems do not offer sufficient flexibility in controlling drug-release rate and sustaining the release over time periods extending from days to months. Therefore specific modified release vaginal delivery systems are continuously under development and are based on mucoadhesive systems. Penetration enhancement may represent a necessary feature for certain delivery systems, particularly when the absorption regards a macromolecule (such as a peptide or a protein). 

Miyzaki, S. Mizuoka, O. Takada, M. External control of drug release and penetration enhancement of the transdermal absorption of indomethacin by ultrasound irradiation. J. Pharm. Pharmacol. 1990, 43, 115-116. 

Drugs are applied topically primarily for local effects however, this route can be used to administer drugs for systemic action. Few drugs readily penetrate intact skin. The absorption of drugs that do penetrate the skin is proportional to the surface area over which they are applied and to their lipid solubility. Increased cutaneous blood flow also enhances absorption. Systemic toxicity can become evident when highly lipid-soluble substances (e.g. lipid-soluble insecticides) are absorbed through the skin. Controlled-release patches are now commonly used in human medicine for transcutaneous drug administration. 

Technologies to increase gastrointestinal retention time Technologies to improve drug release mechanisms of oral preparations Adjuvants to enhance absorption Methods of increasing bioavailability of drugs Penetration enhancement Improved dissolution rate... 

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