Drug Monitoring in Nonconventional Biological Fluids and Matrices

Abstract

Determination of the concentration of drugs and metabolites in biological fluids or matrices other than blood or urine (most commonly used in laboratory testing) may be of interest in certain areas of drug concentration monitoring. Saliva is the only fluid which can be used successfully as a substitute for blood in therapeutic drug monitoring, while an individual's past history of medication, compliance and drug abuse, can be obtained from drug analysis of the hair or nails. Drug concentrations in the bile and faeces can account for excretion of drugs and metabolites other than by the renal route. Furthermore, it is important that certain matrices (tears, nails, cerebrospinal fluid, bronchial secretions, peritoneal fluid and interstitial fluid) are analysed, as these may reveal the presence of a drug at the site of action; others (fetal blood, amniotic fluid and breast milk) are useful for determining fetal and perinatal exposure to drugs. Finally, drug monitoring in fluids such as cervical mucus and seminal fluid can be associated with morpho-physiological modifications and genotoxic effects. Drug concentration measurement in nonconventional matrices and fluids, although sometimes expensive and difficult to carry out, should therefore be considered for inclusion in studies of the pharmacokinetics and pharmacodynamics of new drugs.

Oral fluid as an alternative matrix to monitor opiate and cocaine use in substance-abuse treatment patients

“…Drug transport into oral fluid is regulated by the physiochemical properties of the drug (molecular weight, dissociation constants, lipid solubility, and protein binding) and the membrane. Based on a modified version of the Henderson-Hasselbach equation, it is generally presumed that unbound weakly basic drugs will concentrate in oral fluid, while the opposite occurs for weakly acidic drugs (Pichini et al, 1996). Although less common, low-molecular mass compounds can also be transferred into oral fluid by active secretion or diffusion through pores in the membrane (Haeckel and Hanecke, 1996).…”

Reverse Iontophoresis as a Noninvasive Tool for Lithium Monitoring and Pharmacokinetic Profiling

“…At present, lithium monitoring requires blood sampling. Attempts to use either saliva or urine as alternative matrices have not been successful (3,(7)(8)(9).…”

Optimization of the Weck-Cel Collection Method for Quantitation of Cytokines in Mucosal Secretions

“…The accuracy and consistency of the sampling procedures can ultimately affect experimental outcomes and quantitation of the individual components. Yet the assessment of such fluids is important because it gives insight into the local immune response, physiological modifications induced by infection, and potential drug profiles at the site of action (11,12).There are a number of different methods available for the collection of genital tract secretions, such as cervicovaginal washes, aspiration, and Wick absorption. Each technique has proven its utility but also has a downside.…”

“…The accuracy and consistency of the sampling procedures can ultimately affect experimental outcomes and quantitation of the individual components. Yet the assessment of such fluids is important because it gives insight into the local immune response, physiological modifications induced by infection, and potential drug profiles at the site of action (11,12).…”