Enhancement of transdermal permeation of carvedilol by sonophoresis technique: In vitro evaluation.

In this study, various matrix type transdermal patches containing carvedilol of variable combination of polyvinylpyrrolidone (PVP) and ethylcellulose (EC) were prepared by solvent evaporation technique. The patches were prepared by adding surfactant (sodium lauryl sulphate) to promote drug penetration which was found to increase transdermal transport. Therapeutic frequency ultrasound (1 MHz) and surfactant have been individually shown to enhance transdermal drug transport. In this study, we investigated the synergistic effect of ultrasound and surfactants on transdermal drug delivery. This study provides an investigation of the dependence of therapeutic-frequency sonophoresis on various ultrasound parameters, including ultrasound pretreatment time and the distance of the horn from the skin. Based on the in vitro release and in vitro permeation profile the formulation Fs1 (PVP/EC 1:2) shows the best release. Ultrasound was applied to pretreat the skin using a sonicator operating at a frequency of 1 MHz at an intensity 2 Watts/cm2. The optimum ultrasonication time of 50 min at a distance of 1 cm shows the best release. The skin conductivity enhancement was found to be inversely proportional to the distance of horn from the skin and it is directly proportional to ultrasonication pretreatment time. These findings will be useful in optimizing therapeutic-frequency sonophoresis.

Lactate dehydrogenase isoenzyme patterns in human foetal tissues during development.

The changes in lactate dehydrogenase isoenzyme fractions in various tissues from human foetuses were studied at different stages of development. The isoenzyme pattern changes with the gestation period. The adult pattern is attained at birth in heart, liver, muscle and kidney. Brain shows predominance of cathodic fractions even at birth, but becomes aerobic after 6-12 months. LDH1/LDH5 ratio shows a similar trend. It appears that the adult pattern of LDH isoenzymes consists of predominantly either the faster (aerobic tissues) or slower (anaerobic tissue moving isoenzymes resulting from a gradual shift during foetal and neonatal life.