Early-phase pharmacokinetics of enteral and parenteral nimodipine in patients with acute subarachnoid haemorrhage - a pilot study.

OBJECTIVE: The pharmacokinetics of nimodipine following enteral administration in the early phase after subarachnoid haemorrhage (SAH) has not been described. If a sufficient absorption could be achieved with enterally administered nimodipine, this would be more feasible dosage form and result in a significant reduction in pharmaceutical costs given that the parenteral formulation of nimodipine currently used is tenfold more expensive than the enteral formulation. METHODS: This was a pilot study in which 17 patients with aneurysmal SAH were randomly assigned to receive nimodipine within 24 h after initial bleeding either as an 60 mg tablet/suspension at 4-h intervals, or as a continuous intravenous infusion of 2 mg/h. Serum nimodipine concentrations were measured during the 4 h following the first dose, and at 24 and 72 h on a validated gas chromatography mass spectrometer (GC-MS). RESULTS: Nimodipine AUC values (expressed in mug min/ml) were lower in the eight SAH patients receiving enteral nimodipine [AUC(0-4) range: 0.13-5.4 (median: 0.32); AUC(24-28) range: 0.16-6.1 (0.71); AUC(72-76) range: 0.47-20.6 (1.9)] than in the nine patients receiving a continuous intravenous infusion of nimodipine [AUC(0-4) range: 2.4-4.9 (3.4), p=0.059; AUC(24-28) range: 4.7-10.3 (7.3), p=0.001; AUC(72-76) range: 3.4-8.6 (6.9), p=0.001]. In three of five good-grade SAH patients receiving nimodipine tablets the AUC values were comparable to those of the intravenous administration, but in two good-grade patients with tablets and in all three poor-grade (Hunt&Hess, grade IV) SAH patients receiving the suspension, the rate and extent of nimodipine absorption was negligible. CONCLUSION: This pilot study indicates that the rate and extent of nimodipine absorption following enteral administration in some acute SAH patients could be negligible, and this may particularly be the case in patients with a decreased level of consciousness.

Comparison of oxycodone pharmacokinetics after buccal and sublingual administration in children.

OBJECTIVE: We evaluated and compared the pharmacokinetics of two oral administration routes of oxycodone parenteral liquid (10 mg/mL)--single buccal and sublingual administration--in 30 generally healthy awake children, aged 6-91 months. METHODS: Two groups of children undergoing inpatient surgery were enrolled. In a randomised fashion, children received a single dose of oxycodone 0.2 mg/kg buccally (n = 15) or sublingually (n = 15). Regular blood samples were collected for up to 12 hours, and plasma was analysed for oxycodone, oxymorphone and noroxycodone using gas chromatography-mass spectrometry. RESULTS: Bioavailability was similar after administration at the two instillation sites. The area under the plasma concentration-time curve from time zero extrapolated to infinity (AUCinfinity) was 2400-8000 ng x min/mL (median 4200 ng x min/mL) in the buccal group and 2700-7900 ng x min/mL (median 5500 ng x min/mL) in the sublingual group. After buccal administration, maximum plasma concentration (Cmax) was 5.4-39 ng/mL (16 ng/mL) after buccal and 5.5-42 ng/mL (22 ng/mL) after sublingual administration. Twelve of the 15 children in both groups reached the oxycodone analgesic concentration of 12 ng/mL, which was sustained for 43-209 minutes (median 160 minutes) in the children with buccal oxycodone and for 32-262 minutes (median 175 minutes) in the children with sublingual oxycodone. The terminal elimination half-lives were closely similar in the two groups: 104-251 minutes (median 140 minutes) in the buccal group and 110-190 minutes (150 minutes) in the sublingual group. CONCLUSION: The results of this study show that in young children the absorption of oxycodone is similar after buccal and sublingual instillation.