Drug release sustained formulations

Yuasa H, Torimoto M, Tomei S, Watanabe J (2000) Carrier-mediated drug transport in the colon implications in designing drugs for sustained release formulations. Millennial World Congress of Pharmaceutical Sciences, San Francisco, California, USA, Abstracts p 77... 

Sustained Drug Release from Solid, Semisolid, and Liquid Formulations... 

The choice of mechanism for oral sustained/controlled-release systems is limited by the aqueous solubility of the drug. Thus, diffusional systems are poor choices for low aqueous-soluble drugs since the driving force for diffusion, the concentration in aqueous solution, will be low. The lower limit for the solubility of a drug to be formulated in a controlled-release system has been reported to be O.lmg/mL [11],... 

In order to achieve a sustained drug release and a prolonged therapeutic activity, nanoparticles must be retained in the cul-de-sac and the entrapped drug must be released from the particles at a certain rate. If the release is too fast, there is no sustained release effect. If it is too slow, the concentration of the drug in the tears might be too low to achieve penetration into the ocular tissues [208]. The major limiting issues for the development of nanoparticles include the control of particle size and drug release rate as well as the formulation stability. 

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