Dissolution and permeation characteristics of artemether tablets formulated with two gums of different surface activity

Purpose: To evaluate the dissolution and permeation characteristics of artemether tablets formulated with cashew and prosopis gums, and compare with tablets prepared with acacia gum.Methods: Artemether tablets containing varying concentrations (1.0 to 4.0 %w/w) of cashew and prosopis gums or 3 %w/w of acacia (control) gum as binders were formulated by wet granulation method. The tablets were evaluated for crushing strength, friability and disintegration time. Dissolution and permeation characteristics of the formulations were studied using USP methods.Results: Tablets formulated with prosopis gum had higher crushing strength, higher friability and higher disintegration time compared to those of cashew gum at corresponding binder concentrations. Tablets formulated with 3 %w/w cashew gum exhibited complete drug release within 1 h, 95 % drug permeation in 188 min (in simulated gastric fluid [SGF]) and 95 % permeation in 224 min (under simulated intestinal fluid [SIF] condition) while those made with 3 %w/w prosopis gum exhibited 70.7 % drug release in 1 h, 95 % permeation in 135 min (in SGF) and 95 % permeation in 170 min (under SIF condition).Conclusion: Cashew gum is effective as a binder over a relatively wide range of concentrations to achieve fast drug release though with minimal permeation enhancement while prosopis gum is characterized by delayed drug release but enhanced permeation of the released drug.Keywords: Cashew gum, Acacia, Prosopis, Artemether, Drug release, Dissolution, Permeatio

In vitro evaluation of the antiviral activity of extracts from the lichen Parmelia perlata (L.) Ach. against three RNA viruses

Background: Substances extracted from lichens have previously been reported to possess antimicrobial activities against various groups of bacteria, fungi and viruses. Due to the high abundance of Parmelia perlata in the Eastern parts of Nigeria, we decided to explore whether it possesses antiviral activity against some common animal and human viruses.Methodology: The dried and powdered lichen was extracted with acetone, water and 4% (v/v) NaOH (to yield a crude polysaccharide fraction) using standard methods. The cytotoxicity of the extracts was investigated on HEP-2, Vero and L20 cell lines. The antiviral properties were determined against yellow fever, poliomyelitis and infectious bursal disease virus of chickens using the end-point cytopathic effect assay. Phytochemical evaluations of the extracts were also carried out.Results: Phytochemical tests showed the presence of flavonoids, saponins, tannins, glycosides, steroidal aglycone, carbohydrates and also the presence, in trace amounts, of some oligodynamic elements. Cytotoxicity tests revealed that while L20 was susceptible to the extracts at a concentration of 50 ìg/ml, the extracts were generally toxic to the cell lines at concentrations above 500 ìg/ml. The order of sensitivity of the cell lines was L20 > HEP-2 > Vero. The water and acetone extracts showed no activity against the viruses when tested at concentrations below the cytotoxic level while the crude polysaccharide fraction showed activity against yellow fever virus with an IC50 of 15 ìg/ml. The time of addition of the test extracts to the infected cells did not have significant effect on cytopathic effect inhibition.Conclusions: The results showed that the crude polysaccharide fraction from Parmelia perlata possesses specific antiviral activity against yellow fever virus. It is postulated that a major mechanism of inhibition of yellow fever infection by the crude polysaccharide fraction of the lichen could be by attack on the viral envelope