In vitro phonophoresis: effect of ultrasound intensity and mode at high frequency on NSAIDs transport across cellulose and rabbit skin membranes.

The objective of this study was to evaluate the effect of intensity, mode, and duration of ultrasound application on the transport of three nonsteroidal anti-inflammatory drugs (NSAIDs) across cellulose membrane and rabbit-skin. Ibuprofen, piroxicam and diclofenac sodium were used as the model drugs. Studies were performed in vitro using a modified Franz diffusion assembly adapted to a therapeutic ultrasound transducer. Ultrasound had a significant and positive effect on the transport of the model NSAIDs across cellulose and rabbit skin membranes. Increasing ultrasound intensity from 0.5 to 3.0 W/cm2 led to a proportional increase in drug transport. Continuous ultrasound mode was more effective in enhancing drug transport than the pulsed mode. Diclofenac sodium had the least flux and permeability coefficient. This was attributed to its comparatively lower pKa value that renders the drug more ionizable in the buffer solution, consequently reducing its selective penetration through the membranes. This study demonstrated the therapeutic potential of ultrasound in transdermal delivery of NSAIDs and the synergistic effect of temperature and ultrasound operational parameters on drug transport.

A programmable drug delivery system for oral administration.

A programmable, controlled release drug delivery system has been developed. The device in the form of a non-digestible oral capsule (containing drug in a slowly eroding matrix for controlled release) was designed to utilize an automatically operated geometric obstruction that keeps the device floating in the stomach and prevents it from passing through the remainder of the GIT. Different viscosity grades of hydroxypropyl-methyl-cellulose were employed as model eroding matrices. The duration during which the device could maintain its geometric obstruction (caused by a built-in triggering ballooning system) was dependent on the erosion rates of the incorporated polymers (the capsule in-hosed core matrix). After complete core matrix erosion, the ballooning system is automatically flattened off so that the device retains its normal capsule size to be eliminated by passing through the GIT. In vitro long-term drug delivery from a prototype model was studied using levonorgestril as a model drug. Zero-order release could be maintained for periods ranging between 5 and 20 days before the geometric obstruction is triggered off. The rate of drug release was dependent on the nature, viscosity and ratios of polymer employed.

In vitro release and in vivo absorption of nitrofurantoin and nalidixic acid from ethylcellulose microcapsules.

Ethylcellulose was used as an efficient retarding material to prepare nitrofurantoin or nalidixic acid microcapsules. The dissolution rates of the different preparations have found to increase in alkaline rather than in acidic media. Considerable retardation in the rate and extent of release from 2:1, 1:1 and 1:2 drug-polymer ratios were observed as compared with those of the plain drugs. Absorption study in man proved that formulations containing 2:1 ratios have delayed urinary excretion rates by 2 h, however, the total cumulative amounts excreted from all samples remained almost constant. Man volunteers administered the 2:1 drug-polymer microcapsules did not suffer gastric irritation, usually produced after three consecutive d from taking the plain drugs. Experiments in male albino rats showed that the coated drugs did not produce gastric hemorrhage seen with the same doses of the uncoated ones.