Pharmacokinetics of Abamectin/Levamisole Combination in a Medium Chain Mono and Diglyceride-Based Vehicle and an In Vitro Release and In Vitro In Vivo Correlation Study for Levamisole

Quantitative Analysis of Abamectin, Albendazole, Levamisole HCl and Closantel in Q-DRENCH Oral Suspension Using a Stability-Indicating HPLC-DAD Method

Combination therapy of many anthelmintic drugs has been used to achieve fast animal curing. Q-DRENCH is an oral suspension, containing four different active drugs against GIT worms in sheep, commonly used in Australia and New Zeeland. The anti-parasitic drugs are Albendazole (ALB), Levamisole HCl (LEV), Abamectin (ABA), and Closantel (CLO). The main purpose of this study is to present a new simultaneous stability-indicting HPLC-DAD method for the analysis of the four drugs. The recommended liquid system was 1 mL of Triethylamine/L water, adjusting the pH to 3.5 by glacial acetic acid: acetonitrile solvent (20:80, v/v). Isocratic elusion achieved the desired results of separation at a 2 mL/min flow rate using Zorbax C-18 as a stationary phase. Detection was performed at 210 nm. The linearity ranges were 15.15 to 93.75 μg/mL for ALB, 25 to 150 μg/mL for LEV, 30 to 150 μg/mL for ABA, and 11.7 to 140.63 μg/mL for CLO. Moreover, the final greenness score was 0.62 using the AGREE tool, which reflects the eco-friendly nature. Moreover, the four drugs were determined successfully in the presence of their stressful degradation products. This work presents the first chromatographic method for simultaneous analysis for Q-DRENCH oral suspension drugs in the presence of their stressful degradation products.

Prediction of subcutaneous drug absorption - do we have reliable data to design a simulated interstitial fluid?

For many years subcutaneous (SC) administration has represented the main route for delivering biopharmaceuticals. However, little information exists about the milieu in the subcutaneous tissue, especially about the properties/composition of the fluid present in this tissue, the interstitial fluid (ISF), which is one of the key elements for the drug release and absorption. Better knowledge on SC ISF composition, properties and dynamics may provide better insight into in vivo drug performance. In addition, a simulated SC ISF, which allows better prediction of in vivo absorption of drugs after subcutaneous administration based on in vitro release experiments, would help to improve formulation design, and reduce the number of animal studies and clinical trials required to obtain marketing authorization. To date, a universal medium for predicting drug solubility/release in the interstitial space does not exist. This review provides an overview of the currently available information on composition and physicochemical properties of SC ISF and critically discusses different isolation techniques in the context of information that could be gained from the isolated fluid. Moreover, it surveys current in vitro release media aiming to mimic SC ISF composition and highlights information gaps that need to be filled for designing a meaningful artificial SC ISF.