Drug release and activation

A big problem in membranes for water or gas purification is fouling of the membranes over time. Electrostrictive or magnetostrictive elements could be employed to vibrate at a surface to help dislodge debris. Conversely, the strictive materials could be used to create a controlled amount of porosity and therefore gradient porosities for improved separations or even multiple component separations of molecules. Possibilities for improved controlled drug release and activation abound. 

Fattale, E. Rojas, J. Roblot-Treupal, L. Andremont, A., Couveur, P. Ampicillin-loaded liposomes and nanoparticles Comparison of drug loading, drug release and in vitro antimicrobial activity. J. Microcapsulation 8 (I), p. 29-36, 1991... 

Henrymichelland S, Alonso MJ, Andremont A, Maincen P, Sauzieres J, Couvreur P (1987) Attachment of antibiotics to nanoparticles-preparation, drug-release and antimicrobial activity in vitro. Int J Pharm 35 121-127. 

Lim HI, Masin D, McIntosh NL, Madden TD, Bally MB. Role of drug release and liposome-mediated drug delivery in governing the therapeutic activity of liposomal mitoxantrone used to treat human A431 and LSI80 solid tumors. J Pharmacol Exp Ther 2000 292 337. 

The cumulative drug release and the drug release rate for constant activity and nonconstant activity reservoirs of other geometrical barriers are shown in Table 6.3. 

The Cumulative Drug Release and Release Rate for Constant Activity and Nonconstant Activity Reservoirs... 

Yan, C., Chen, D., Gu, J., and Qin, J. (2006), Nanoparticles of 5-fluorouracil (5-FU) loaded V-succinyl-chitosan (Suc-Chi) for cancer chemotherapy Preparation, characterization—in-vitro drug release and anti-tumour activity, J. Pharm. Pharmacol., 58(9), 1177-1181. 

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. 

The principle of a purely osmotically controlled drug delivery was disclosed some 15 years ago [147]. The so-called elementary osmotic pump consists of a core containing the drug (and if necessary an osmotic agent) and a CA semipermeable membrane with a micro-orifice drilled usually by a laser beam. Drug release is activated by the transport of water through the semipermeable... 

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