DRUG-MONITORING IN NONCONVENTIONAL BIOLOGICAL-FLUIDS AND MATRICES

Determination of the concentration of drugs and metabolites in biologi cal fluids or matrices other than blood or urine (most commonly used i n laboratory testing) may be of interest in certain areas of drug conc entration monitoring. Saliva is the only fluid which can be used succe ssfully as a substitute for blood in therapeutic drug monitoring, whil e an individual's past history of medication, compliance and drug abus e, can be obtained from drug analysis of the hair or nails. Drug conce ntrations in the bile and faeces can account for excretion of drugs an d metabolites other than by the renal route. Furthermore, it is import ant that certain matrices (tears, nails, cerebrospinal fluid, bronchia l secretions, peritoneal fluid and interstitial fluid) are analysed, a s these may reveal the presence of a drug at the site of action; other s (fetal blood, amniotic fluid and breast milk) are useful for determi ning fetal and perinatal exposure to drugs. Finally, drug monitoring i n fluids such as cervical mucus and seminal fluid can be associated wi th morpho-physiological modifications and genotoxic effects. Drug conc entration measurement in nonconventional matrices and fluids, although sometimes expensive and difficult to carry out, should therefore be c onsidered for inclusion in studies of the pharmacokinetics and pharmac odynamics of new drugs.