SALIVA: A NEW CHALLENGE FOR ANTIRETROVIRALS DETECTION? Insights from mass spectrometry

BALDO, MATÍAS N; HUNZICKER, GABRIEL A; MURGUIA, MARCELO C; HEIN, GUSTAVO J

Cordoba

Congreso; 3era Reunion Internacional de Ciencias Farmaceuticas; 2014

Colegio Farmaceutico de Cordoba

Saliva containsonly the non-protein-bound fraction of total drug and allows an adequatecorrelation between drug concentration and its pharmacological effect. Theantiretroviral Efavirenz (EFV) needs constant monitoring and comparative relative bioavailability(RBA) studies of EFV in an alternative matrix required advanced technology.The main objectives were: (i) to develop and to validate a simple methodby UFLC-MS/MS useful for a RBA study with human saliva and (ii) to find acorrelation between saliva and plasma results.A C18 column (100 mm x 2.1 mm, i.d, 3 µm)was used. Elution was performed in an isocratic mode using: methanol?water(10:90 (v/v)), and 5mM ammonium formate in 97% MeOH as mobile phase. Samplepreparation involved a simple protein precipitation and dilution.An RBA study of 600 mg EFV tablets was performed ina single-dose, randomized-sequence, open-label, two-way crossover study, in 16 healthymen. Saliva and plasma samples were taken at the same time. Pharmacokineticparameters were calculated by WinNonlin®.The method showed linearity (r >0.999) over theworking range (1.00?99.85 ng/mL). Accuracy (85-115%) and precision (%CV<15)were according to the international bioequivalence criteria. Cmax,AUC0-t and AUC0-∞ for test and reference formulations were:(24.19 and 29.41) ng/mL, (539.82 and 795.24) ng/mL/h, (702.45 and 951.85) ng/mL/h,respectively. These results were comparable to those thrown by the study in plasma, which was performed by HPLC-UV-vis (λ=250 nm). The EFV concentrationcould be obtained in saliva by the relation: [Saliva EFV] = 0.009 [Plasma EFV].There was a good linear correlation (r =0.84) between the EFV concentrations inboth fluids.A rapid and accurate UFLC-MS/MS method wasdeveloped. Saliva demonstrated to be a suitable surrogate toevaluate EFV tablet pharmacokinetics and it has been fairly comparable toplasma with excellent biosafety advantages for RBA and therapeutic drug monitoring studies.