Salivary Therapeutic Drug Monitoring of Anti-Tuberculosis Drugs

TDM (Therapeutic Drug Monitoring) with blood samples is already part of the treatment of some tuberculosis (TB) patients to reduce development of drug resistance and toxic drug concentrations. Performing TDM with saliva instead of plasma or serum could reduce the burden of blood sampling. This study examines if this non-invasive sampling of saliva could be used for TDM of several anti-TB drugs.

The study is an observational cohort study with adult tuberculosis patients as subjects. The drugs that are studied are isoniazid, rifampicin, ethambutol, pyrazinamide, moxifloxacin, amikacin, kanamycin, capreomycin, ethionamide, prothionamide, cycloserine, terizidone, linezolid, clofazimine, bedaquiline, delamanid, p-aminosalicylic acid (PAS), imipenem-cilastatin, meropenem, ertapenem, amoxicillin-clavulanate and thioacetazone.

Saliva samples will be taken simultaneously with blood samples for standard TDM. Serum/plasma and saliva drug concentrations will be determined with a validated LC-MS/MS (liquid chromatography-tandem mass spectrometry) method. The correlation and linearity between saliva and plasma/serum concentrations will be tested. The saliva-plasma or serum ratio based on area under the time-concentration curve (AUC) is calculated for the investigated anti-TB drugs. Also pharmacokinetic parameters in serum/plasma and saliva will be calculated and compared to provide a complete image of pharmacokinetics of the anti-TB drugs in saliva.

Inclusion criteria

• Tuberculosis is confirmed by culture or molecular test
• Patient is treated with anti-tuberculosis drugs included in study
• Patient receives Therapeutic Drug Monitoring (TDM) in routine care
• Patient signed informed consent

Exclusion criteria

• Patient with severe problems in the oral cavity, making saliva sampling painful