Effect of lyophilization on the characteristics and stability of melanin loaded liposomes

The present study was directed to optimize the stability of melanin liposomes utilizing the technique of lyophilization. Two types of cryoprotectants; sucrose and lactose, each in two concentrations of 5% and 10% were used. Lyophilized liposomes [10% lactose] either fresh or stored for one year at 5°C showed no significant changes [P>0.05] in the phase transition temperatures [Tc], structure and shape, and size distribution of the fresh unlyophilized liposomes. The fresh unlyophilized liposomes were unilamellar with Tc of 41.6°C and an average size of 5.21 micro m. The stored unlyophilized liposomes showed a significant [P<0.05] decrease in Tc [32.8°C] and increase in the average size [15.6 micro m] with the formation of onion- like multilamellar vesicles compared with the fresh unlyophilized ones. Lyophilization of melanin liposomes with different cryoprotectants significantly [P<0.001] decreased the rate of leakage of entrapped melanin from the liposomal structure compared with the unlyophilized ones. This cryoprotection effect was significantly [P<0.05] increased by the use of lactose and by increasing the cryoprotectant concentration. The entrapped melanin in lyophilized liposomes with 10% lactose was chemically stable for six months at 5°C as evaluated by mass spectroscopic analysis. As a conclusion, lyophilization with 10% lactose maintained the chemical stability of melanin and significantly improved the physical stability of melanin liposomes

Ketoconazole in pityriasis versicolor with monitoring its serum level using a simple bioassay technique

A simple agar-well diffusion bioassay method for measurement of ketoconazole was evaluated in which a medium containing 0.7% trypticase peptone and a strain of Candida pseudotropicalis as assay organism were used. A linear relationship between zone diameters and Log 10 concentrations of the drug over the pharmacologically relevant ranges of 0.5-20 mug/ml was obtained [F=1324.038; p <0.001]. The variability among measurements was found to be 0.3421 denoting that the technique was precise and hence was used to monitor serum level of patients of this study. Twenty two patients with pityriasis versicolor therapeutically received a ten-day course of ketoconazole to investigate the efficacy of this short course of the drug. Patients were assessed both clinically [for scaling and pigmentation] and laboratory [KOH scraping] before starting ketoconazole therapy, at the end of the course [day 10] and on day [30]. Serum ketoconazole levels of patients ranged from 0-6.9 mug/ml on the second day of therapy and 0.9-7.1 mug/ml on day [10]. Before starting therapy, all patients showed positive KOH preparation, 21 [95.5%] showed scaly lesion and 12 patients [45.5%] had pigmented lesion. On day [30] only one patient had scaly lesion while two patients still had pigmented lesion and KOH positive smear. The improvement seen in both clinical and laboratory parameters in the follow-up period was highly significant [P <0.001] when compared to pretreatment figures. The 10-day course of ketoconazole in the treatment of pityriasis versicolor was recommended

Gardnerella vaginitis [evaluation of two diagnostic screening procedures]

Gardnerella vaginalis was isolated from 37 [17%] out of 218 women presenting with vaginal discharge. Significant association was noted between G. vaginalis isolation and previous history of recurrent attacks of vaginitis than in non G. infected group [P <0.001]. Two screening tests [clue cell investigation and amine volatization test], suggested to be of a diagnostic value, were evaluated in comparison with bacterial culture. Clue cell investigation sensitivity was found to be 0.92 and specificity 0.86. The positive predictive value of the test was 0.58 and its negative predictive value was 0.98. On the other h and, the sensitivity of amine volatization test was 0.45 and its negative predictive value was 0.90. Simultaneous use of both tests together showed sensitivity 0.5 and specificity 0.97. The positive predictive value was 0.74 and would encourage attempt to further doing bacterial culture. The negative predictive value was extremely high 0.96 and hence could exclude G. vaginalis as the causative agent