full issue - Association of Biotechnology and Pharmacy

Current Trends in Biotechnology and PharmacyVol. 5 (2) 1173-1182 April 2011. ISSN 0973-8916 (Print), 2230-7303 (Online)1175speed and temperature of 32 o C. Samples werecollected at preset time intervals and analyzedusing UV-Vis spectrophotometer (Elico, India) at282 nm.Release kinetics and mechanisms of drugrelease: Different kinetic models, zero order, firstorder (8), Higuchi and Korsmeyer expressions(8, 9) were applied to interpret the drug releasekinetics to know the mechanism of drug releasefrom these matrix systems with the help ofequations 1-4.M t=M 0+K 0t—————————(1)LnM t=LnM 0+K 1t—————(2)M t=K Ht 1/2 ——————————(3)M t/M =K kt n ————————(4)M tcumulative amount of drug release at time t;M 0, is the initial amount of drug K 0,K 1,K HandK Kare rate constants for zero order, first order,Higuchi and Korsemeyer model respectively; M t/M is the fraction of drug release at time t n,release exponent indicative of the operatingrelease mechanism. The correlation coefficientvalues (r 2 ) presented in table 288Moisture absorption studies: The films wereweighed accurately and placed in a dessicatorcontaining 100 mL of saturated solution ofaluminium chloride (79.5 % RH). After 3 days,the films were taken out and weighed, thepercentage of moisture uptake was calculated asthe difference between final and initial weight withrespect to initial weight (10).Moisture content: The patches were weighedand kept in a desiccator containing calcium chlorideat 40 o C for 24 hr. The final weight was notedwhen there was no further change in the weightof patch. The percentage of moisture content wascalculated as a difference between initial and finalweight with respect to initial weight (11).Measurement of mechanical properties:Mechanical properties, elongation at break (E.B)and tensile strength (T.S) of the films wereevaluated using a microprocessor based advancedforce gauze equipped with a motorized test stand(Ultra Test, Mecmesin, West Sussex, UK),equipped with 25 kg load cell. Film strip (60x10Table 1. Composition of LCDP transdermal patchesFormulation Ingredient (mg)LCDP EC20 ERL100 PVPLE1 (10:0) 90 - 2500 -LE2 (7.5:2.5) 90 - 1875 625LE3 (5.0:5.0) 90 - 1250 1250LE4 (2.5:7.5) 90 - 625 1875LP1 (10:0) 90 2500 - -LP2 (7.5:2.5) 90 1875 - 625LP3 (5.0:5.0) 90 1250 - 1250LP4 (2.5:7.5) 90 625 - 1875LCDP, Lacidipine; EC20, Ethyl cellulose 20, ERL 100, Eudrgait RL 100; PVP, Polyvinyl pyrrolidoneSolvent system used is 25 mL of 50:50 of dichloromethane and methanolPlasticizer 20 % w/v of dibutylphathalated-limonene 8 % w/v was incorporatedDevelopment of matrix type transdermal patches of lacidipine