In tuberculosis patients, salivary concentrations will be compared to plasma/serum concentrations of several anti-tuberculosis drugs. If salivary concentrations correctly represent blood concentrations, this non-invasive sampling of saliva could be used for TDM of the tested 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.
Study Type
OBSERVATIONAL
Enrollment
24
Stimulated saliva samples are taken using cotton rolls.
Simultaneously with saliva sampling.
University Medical Center Groningen (UMCG) Beatrixoord
Haren, Provincie Groningen, Netherlands
Saliva-plasma ratio or saliva-serum ratio
Ratio of salivary versus blood concentration calculated with salivary and plasma/serum values of area under the time-concentration curve (AUC)
Time frame: 0, 0.5, 1, 2, 3, 4, 7 hours post-dose for isoniazid, rifampicin, ethambutol and pyrazinamide or 0, 1, 2, 3, 4, 8 hours post-dose for all other drugs
Salivary drug concentration
Measured drug concentration in saliva
Time frame: 0, 0.5, 1, 2, 3, 4, 7 hours post-dose for isoniazid, rifampicin, ethambutol and pyrazinamide or 0, 1, 2, 3, 4, 8 hours post-dose for all other drugs
Plasma/serum drug concentration
Measured drug concentration in plasma or serum
Time frame: 0, 0.5, 1, 2, 3, 4, 7 hours post-dose for isoniazid, rifampicin, ethambutol and pyrazinamide or 0, 1, 2, 3, 4, 8 hours post-dose for all other drugs
Area under the time-concentration curve (AUC) in saliva and plasma/serum
Calculated in both saliva and plasma/serum using the drug concentration at all time points.
Time frame: 0, 0.5, 1, 2, 3, 4, 7 hours post-dose for isoniazid, rifampicin, ethambutol and pyrazinamide or 0, 1, 2, 3, 4, 8 hours post-dose for all other drugs
Peak concentration (Cmax) in saliva and plasma/serum
Calculated in both saliva and plasma/serum using the drug concentration at all time points.
Time frame: 0, 0.5, 1, 2, 3, 4, 7 hours post-dose for isoniazid, rifampicin, ethambutol and pyrazinamide or 0, 1, 2, 3, 4, 8 hours post-dose for all other drugs
Time of peak concentration (Tmax) in saliva and plasma/serum
Calculated in both saliva and plasma/serum using the drug concentration at all time points.
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Time frame: 0, 0.5, 1, 2, 3, 4, 7 hours post-dose for isoniazid, rifampicin, ethambutol and pyrazinamide or 0, 1, 2, 3, 4, 8 hours post-dose for all other drugs
Trough concentration (Cmin) in saliva and plasma/serum
Calculated in both saliva and plasma/serum using the drug concentration at all time points.
Time frame: 0, 0.5, 1, 2, 3, 4, 7 hours post-dose for isoniazid, rifampicin, ethambutol and pyrazinamide or 0, 1, 2, 3, 4, 8 hours post-dose for all other drugs
Clearance (Cl) in saliva and plasma/serum
Calculated in both saliva and plasma/serum using the drug concentration at all time points.
Time frame: 0, 0.5, 1, 2, 3, 4, 7 hours post-dose for isoniazid, rifampicin, ethambutol and pyrazinamide or 0, 1, 2, 3, 4, 8 hours post-dose for all other drugs
Half-life (t1/2) in saliva and plasma/serum
Calculated in both saliva and plasma/serum using the drug concentration at all time points.
Time frame: 0, 0.5, 1, 2, 3, 4, 7 hours post-dose for isoniazid, rifampicin, ethambutol and pyrazinamide or 0, 1, 2, 3, 4, 8 hours post-dose for all other drugs
Elimination constant (Kel) in saliva and plasma/serum
Calculated in both saliva and plasma/serum using the drug concentration at all time points.
Time frame: 0, 0.5, 1, 2, 3, 4, 7 hours post-dose for isoniazid, rifampicin, ethambutol and pyrazinamide or 0, 1, 2, 3, 4, 8 hours post-dose for all other drugs