A. Ramadan

Pharmacokinetics of tilmicosin in serum and milk of goats.

Tilmicosin was administered to goats intravenously and subcutaneously to determine its concentration in blood and milk and its kinetic behaviour. After a slow intravenous injection, the serum concentration-time curve indicated a two compartment open model with a mean (SEM) elimination half-life (t1/2 beta S) of 4.36 (0.04) hours. After a subcutaneous injection the drug was eliminated more slowly from serum and milk, with t1/2 beta S of 29.3 and 41.4 hours, respectively. The apparent volume of distribution of tilmicosin was more than 1 litre kg-1. The peak serum tilmicosin concentration was 1.56 micrograms ml-1 6.39 hours after a subcutaneous injection of 10 mg kg-1. Tilmicosin was extensively secreted into milk, reaching a maximum concentration of 11.6 micrograms ml-1 and having a large AUCmilk/AUCserum ratio of approximately 12:1. Tilmicosin was detectable in milk for 11 days after a single subcutaneous dose.

Kinetic disposition, systemic bioavailability and tissue distribution of salinomycin in chickens

Salinomycin was administered to chickens orally and intravenously to determine blood concentration, kinetic behaviour, bioavailability and tissue residues. The drug was given by intracrop and intravenous routes in a single dose of 20 mg kg-1 body-weight. The highest serum concentrations of salinomycin were reached half an hour after oral dosage with an absorption half-life (t0.5(ab)) of 3.64 hours and elimination half-life (t0.5(beta)) of 1.96 hours. The systemic bioavailability percentage was 73.02 per cent after intracrop administration, indicating the high extent of salinomycin absorption from this route in chickens. Following intravenous injection the kinetics of salinomycin can be described by a two-compartment open model with a t1/2(alpha) of 0.48 hours, Vd ss (volume of distribution) of 3.28 litre kg-1 and Cl(beta) (total body clearance) of 27.39 ml kg-1 min-1. The serum protein-binding tendency of salinomycin as calculated in vitro was 19.78 per cent. Salinomycin concentrations in the serum and tissues of birds administered salinomycin premix (60 ppm) for two weeks were lower than those after administration of a single intracrop dose of pure salinomycin (20 mg kg-1 bodyweight). The highest concentration of salinomycin residues were present in the liver followed by the kidneys, muscles, fat, heart and skin. No salinomycin residues were detected in tissues after 48 hours except in the liver and these had disappeared completely by 72 hours.

Anticoccidial efficacy of toltrazuril and halofuginone against Eimeria tenella infection in broiler chickens in Egypt

The anticoccidial activities of toltrazuril and halofuginone against Eimeria tenella were tested in broiler chickens. Comparisons were made between ummedicated infected and uninfected control birds in addition to infected groups given either toltrazuril at 37.5, 75 and 150 ppm in the drinking water, or halofuginone at 1.5, 3 and 6 ppm in the feed. Both drugs were highly efficacious against E tenella. Treatment improved the bodyweight gain and survival percentage in comparison with the unmedicated, infected group. Intestinal lesions, faecal and oocyst scores and oocyst shedding in dropping were significantly reduced by both drugs. Toltrazuril gave better protection than halofuginone; 75 and 150 ppm toltrazuril in drinking water gave good protection when administered four and five days after inoculation.

Kinetic disposition, systemic bioavailability and tissue distribution of apramycin in broiler chickens

Apramycin was administered to chickens orally, intramuscularly and intravenously to determine blood concentration, kinetic behaviour, bioavailability and tissue residues. Single doses of apramycin at the rate of 75 mg kg-1 body weight were given to broiler chickens by intracrop, i.m. and i.v. routes. The highest serum concentrations of apramycin were reached 0.20 and 0.76 hours after the oral and i.m. doses with an absorption half-life (t1/2(ab.)) of 0.10 and 0.19 hours and an elimination half life (t1/2(beta)) of 1.22 and 2.31 hours respectively. The systemic bioavailability was 2.0 and 58 per cent after intracrop and i.m. administration, respectively, indicating poor absorption of the drug when given orally. Following i.v. injection, the kinetics of apramycin was described by a two-compartment open model with a (t1/2(alpha)) of 1.5 hours, (t1/2(beta)) of 2.1 hours. Vd(ss) (volume of distribution) of 4.82 litre kg-1 and C1(B) (total body clearance) of 1.88 litre kg-1 hour-1. The serum protein-binding of apramycin was 26 per cent. The highest tissue concentrations of apramycin were present in the kidneys and liver. No apramycin residues were detected in tissues after six hours except in the liver and kidneys following intracrop dosing and kidneys following i.m. administration.

Liposomal Encapsulation of Amikacin Sulphate for Optimizing Its Efficacy and Safety

Aims: The abstract of the current study was to formulate amikacin sulfate in a liposomal formulatiom for enhancing its efficacy and safety. Place and Duration of Study: Pharmaceutical Technology Department, Pharmaceutical and Drug Industries Research Division, National Research Centre (NRC), Dokki, Cairo, Egypt, between 2010-2013. Original Research Article El-Ridy et al.; BJPR, 5(2): 98-116, 2015; Article no.BJPR.2015.010 99 Methodology: Amikacin sulfate liposomes were prepared by the vortex dispersion method using dipalmitoyl phosphatidyl choline (DPPC), cholesterol (CHOL) and charge inducing agent (CIA). Dicetyl phosphate (DCP) and Stearyl amine (SA) were added as the negative and positive charge inducing agents respectively. Characterization of the prepared amikacin sulphate liposomes was performed. In-vitro release of selected formulations was estimated. A stability study for 45 days was performed. Investigation of the optimum dose for sterilization of amikacin sulfate liposomes was carried out. Selected amikacin sulfate liposomal formulations activities were evaluated against Escherichia coli infection in mice and compared to the free drug. Results: The entrapment efficiencies ranged from 43.6±1.81 to 62.5±2.57%, the vesicles are well identified and present in a nearly perfect sphere like shape ranging in size from 54.3±11 to 362.1±56 nm and the polydospersity index values of all liposomal formulations were < 0.3. DSC of different liposomal formulations shows a change in transition temperature of the main phospholipids. In-vitro release profiles revealed biphasic release of the drug from liposomes. Physical stability performed at 2-8oC for 45 days revealed low leakage of drug from all liposomal formulations investigated. Sterilization using gamma radiations revealed that a dose of 25 KGy was the optimum sterilization dose. The results also revealed less number of colonies forming units (cfu/ml) in the case of amikacin sulfate liposomes than the unentrapped drug. Conclusion: It can be fulfilled from this work that amikacin sulfate liposomes represent promising carrier for delivery of amikacin offering good physical stability, high entrapment effeciencies and controlled drug release.

Effect of pantothenic acid on disposition kinetics and tissue residues of sulphadimidine in chickens

Sulphadimidine was administered to chickens via the intracrop route to determine plasma concentrations of the unchanged sulphonamide and its acetylated derivatives, kinetic disposition, tissue residues and acetylation. The sulphadimidine was given alone (group 1) at a dose of 200 mg kg-1 bodyweight. Pantothenic acid was given via the intracrop route at a dose of 100 mg kg-1 bodyweight one hour before (group 2) and six hours after (group 3) sulphadimidine administration (200 mg kg-1 bodyweight intracrop). The highest plasma concentrations of sulphadimidine in groups 1, 2 and 3 were reached in 1.73, 1.62 and 1.71 hours, respectively, following intracrop administration. In birds of groups 1, 2 and 3 no sulphadimidine was detected at 72, 24 and 48 hours, respectively, following its administration. Estimation of sulphadimidine in most of the body tissues revealed that all tissues examined had lower concentrations than plasma. In chickens given pantothenic acid (groups 2 and 3) before and after sulphadimidine administration, an increase in the concentration of N4 acetylated derivatives of sulphadimidine was observed compared with birds given sulphadimidine alone (group 1).