Pharmacokinetic characteristics of drugs regarding skeletal muscles

Drugs may be given by different routes in order to exert systemic or local effect. From the pharmacokinetics point of view, considering muscles as body compartment, it is important to characterize absorption after intramuscular (IM) drug administration, and drug distribution into muscle following drug administration. IM injection is characterized by invasive procedure puncturing the skin with a needle in order to inject the drug directly into a large body muscle for the prophylactic or therapeutic purposes. The rate and extent of drug absorption are determined by formulation, physicochemical properties of drugs, and physiological characteristics of the site of administration. When intravenously or non-IM drug is administered, distribution may occur at various rates and to various extents in different tissues including muscles. Rate of drug distribution depends on vascular membrane permeability, regional blood flow, cardiac output and perfusion rate of the tissue, while extent of distribution is defined by drug’s ability to bind to Correspondence/Reprint request: Dr. Milica Prostran, Department of Pharmacology, Clinical Pharmacology and Toxicology, School of Medicine, University of Belgrade, P.O.Box 38, 11129, Belgrade, Serbia E-mail: [email protected] Katarina Vučićević et al. 30 plasma and/or tissue proteins, its liposolubility, and relation of pKa of drug and pH of environment. The article gives an overview of the pharmacokinetic aspects of absorption following IM injection, and distribution of drugs in muscular tissue.