Therapeutic Drug Monitoring of Vancomycin in Patients with Altered Pharmacokinetics: A Narrative Review on Pharmacokinetic Assessments

Introduction: Vancomycin is a glycopeptide antibiotic that is considered as the drug of choice against many Gram-positive bacterial infections, especially Methicillin-resistant Staphylococcus aureus (MRSA). Also, it is a hydrophilic drug with predominantly renal elimination. Given the vancomycin narrow therapeutic index, therapeutic drug monitoring (TDM) is essential to achieve an optimum clinical response and avoid vancomycin-induced adverse drug reactions including nephrotoxicity and ototoxicity. Although different studies are available on vancomycin pharmacokinetic assessment and vancomycin TDM, still there are controversies regarding the selection among different pharmacokinetic parameters including trough concentration (Cmin), the daily area under the curve to minimum inhibitory concentration (AUC24h/MIC) ratio, AUC of intervals (AUCτ), elimination constant (k), vancomycin clearance (ClV) and methods of their calculations for TDM purposes. Methods: In this review, different pharmacokinetic parameters for vancomycin TDM have been discussed in detail along with corresponding advantages and disadvantages, based on the literature review. Determination of vancomycin concentration at steady state (Css) during 24h continuous injection are mentioned. Also, vancomycin pharmacokinetic assessments are discussed in detail in patients with altered pharmacokinetic parameters including those with renal and/or hepatic failure, critically ill patients, patients with burn injuries, intravenous (IV) drug users, obese and morbidly obese patients, those with cancer, patients undergoing organ transplantation, and vancomycin administration during pregnancy and lactation. Results and Discussion: An individualized dosing regimen is required to guarantee the optimum therapeutic results and minimize severe adverse reactions such as acute kidney injury (AKI) in these special groups of patients with altered pharmacokinetic parameters. Also, according to the pharmacoeconomic data on vancomycin TDM, pharmacokinetic assessments would be cost-effective in the mentioned groups of patients with altered pharmacokinetics and associated with shorter hospitalization period, faster clinical stability status, and shorter courses of inpatient vancomycin administration.