WHAT IS ALREADY KNOWN ABOUT THE SUBJECT• Midazolam is a frequently used probe drug for CYP3A phenotyping in plasma. Midazolam and its hydroxy-metabolites can be detected in saliva. WHAT THIS STUDY ADDS• The concentrations of midazolam and its hydroxy-metabolites are much lower in saliva than in plasma, but the midazolam concentrations in both matrices show a significant linear correlation.• Saliva appears to be a suitable matrix for CYP3A phenotyping with midazolam, but very sensitive methods are required due to the low concentrations of midazolam and its hydroxy-metabolites. AIMSTo compare midazolam kinetics between plasma and saliva and to find out whether saliva is suitable for CYP3A phenotyping. METHODSThis was a two way cross-over study in eight subjects treated with 2 mg midazolam IV or 7.5 mg orally under basal conditions and after CYP3A induction with rifampicin. RESULTSUnder basal conditions and IV administration, midazolam and 1′-hydroxymidazolam (plasma, saliva), 4-hydroxymidazolam and 1′-hydroxymidazolam-glucuronide (plasma) were detectable. After rifampicin, the AUC of midazolam [mean differences plasma 53.7 (95% CI 4.6, 102.9) and saliva 0.83 (95% CI 0.52, 1.14) ng ml -1 h] and 1′-hydroxymidazolam [mean difference plasma 11.8 (95% CI 7.9 , 15.7) ng ml -1 h] had decreased significantly. There was a significant correlation between the midazolam concentrations in plasma and saliva (basal conditions: r = 0.864, P < 0.0001; after rifampicin: r = 0.842, P < 0.0001). After oral administration and basal conditions, midazolam, 1′-hydroxymidazolam and 4-hydroxymidazolam were detectable in plasma and saliva. After treatment with rifampicin, the AUC of midazolam [mean difference plasma 104.5 (95% CI 74.1, 134.9) ng ml -1 h] and 1′-hydroxymidazolam [mean differences plasma 51.9 (95% CI 34.8, 69.1) and saliva 2.3 (95% CI 1.9, 2.7) ng ml -1 h] had decreased significantly. The parameters separating best between basal conditions and post-rifampicin were: (1′-hydroxymidazolam + 1′-hydroxymidazolam-glucuronide)/midazolam at 20-30 min (plasma) and the AUC of midazolam (saliva) after IV, and the AUC of midazolam (plasma) and of 1′-hydroxymidazolam (plasma and saliva) after oral administration. CONCLUSIONSSaliva appears to be a suitable matrix for non-invasive CYP3A phenotyping using midazolam as a probe drug, but sensitive analytical methods are required.

Midazolam (MDZ), a short-acting benzodiazepine, is a widely accepted probe drug for CYP3A phenotyping. Published methods for its analysis have used either therapeutic doses of MDZ, or, if employing lower doses, were mostly unable to quantify the two hydroxy metabolites. In the present study, a sensitive and specific liquid chromatography/electrospray ionization tandem mass spectrometry method was developed and validated for the quantitative determination of MDZ and two of its metabolites (1'-hydroxymidazolam (1'-OHMDZ) and 4-hydroxymidazolam (4-OHMDZ)) in human plasma and oral fluid. After liquid-liquid extraction with hexane/dichloromethane (73:27, v/v), the analytes were separated on a Luna C18(2) (100 x 2.1 mm) analytical column using gradient elution. Detection was achieved using tandem mass spectrometry on an ion trap mass spectrometer. Midazolam-d6 was used as internal standard for quantification. The calibration curves were linear (R2 >0.998) between 0.05 and 20 ng/mL for MDZ and both metabolites in both matrices. Using 1 mL samples, the limit of detection was 0.025 ng/mL and the limit of quantification was 0.05 ng/mL for MDZ and the hydroxy metabolites in both matrices. Intra- and inter-day accuracies, determined at three different concentrations, were between 92.1 and 102.3% and the corresponding coefficients of variation were <7.3%. The average recoveries were 90.6%, 86.7% and 79.0% for MDZ, 1'-OHMDZ and 4-OHMDZ in plasma and 95.3%, 96.6% and 86.8% for MDZ, 1'-OHMDZ and 4-OHMDZ, respectively, in oral fluid. The method was successfully applied to a pharmacokinetic study, showing that MDZ and its hydroxy metabolites can be determined precisely in in vivo samples obtained following a single oral or intravenous dose of 2 mg MDZ. The method appears to be useful for CYP3A phenotyping in plasma using sub-therapeutic MDZ doses, but larger studies are needed to test this assumption.

Lycopene can be dissolved within the oil phase of oil‐in‐water emulsions to increase bioavailability in water‐dispersible systems. It is sensitive to oxidative conditions and easily undergoes isomerization at high temperatures. Degradation kinetics and isomerization of lycopene in oil‐in‐water‐emulsions were investigated as a function of thermal treatment and oxygen content. Lycopene degradation was found to follow a first‐order kinetics and rate constants were determined. Higher temperatures are directly correlated with increasing lycopene losses. Moreover, thermal treatment leads to a significant decrease of the concentrations of all‐trans and 13‐cis isomer, while the concentration of the 9‐cis isomer increased. Oxygen‐free conditions reduce lycopene losses significantly.

The authors present a patient with refractory epilepsy who was treated with very high doses (up to 4 mg/min) of intravenous midazolam, phenytoin, carbamazepine, and other antiepileptics. Because it was known from the literature that the half-life of midazolam can increase at high dosage, the kinetics of midazolam (MDZ), 1'-hydroxymidazolam, and 4-hydroxymidazolam were assessed at steady state (dosage 1 mg/min) and after stopping treatment. Total body clearance of MDZ (33 L/kg) and intrinsic hepatic clearance (19 mL/min/kg) at steady state were both five to 10 times higher than after normal therapeutic doses, demonstrating hepatic cytochrome (CYP) 3A induction. Despite the high body clearance, the half-life of MDZ was in the range of 24 hours, approximately 10 times higher than after normal therapeutic doses. The volume of distribution at steady state was 33 L/kg, approximately 50 times higher than after normal therapeutic doses. The free fraction of MDZ was 58% at steady state, much higher than the 3% to 6% at normal therapeutic doses. The kinetics of intravenous MDZ is strongly dependent on its dose and on hepatic CYP3A activity. Even in patients with hepatic CYP3A induction, the half-life of MDZ increases with high doses as a result of a rise in its volume of distribution, which is a consequence of an increase in the free fraction of MDZ.

Liegt ein Patient nach einem Unfall im Wachkoma, ist das f?r die Angeh?rigen eine fast surreale Situation. Der Betroffene scheint wach ? und ist trotzdem gef?hlt 1.000 Meilen entfernt. In sehr vielen F?llen k?nnen die Patienten, unterst?tzt durch eine intensive Therapie, St?ck f?r St?ck ihr altes Bewusstsein zur?ckerlangen. Allerdings ist das ein Prozess, der allen Beteiligten enorm viel Geduld und Kraft abverlangt.