Human Mitragynine and 7-Hydroxymitragynine Pharmacokinetics after Single and Multiple Daily Doses of Oral Encapsulated Dried Kratom Leaf Powder.

Kratom leaves, consumed by millions worldwide as tea or ground leaf powder, contain multiple alkaloids, with mitragynine being the most abundant and responsible for most effects. Mitragynine is a partial µ-opioid receptor agonist and competitive antagonist at κ- and δ-opioid receptors; however, unlike morphine, it does not activate the ß-arrestin-2 respiratory depression pathway. Due to few human mitragynine data, the largest randomized, between-subject, double-blind, placebo-controlled, dose-escalation study of 500-4000 mg dried kratom leaf powder (6.65-53.2 mg mitragynine) was conducted. LC-MS/MS mitragynine and 7-hydroxymitragynine plasma concentrations were obtained after single and 15 daily doses. Mitragynine and 7-hydroxymitragynine Cmax increased dose proportionally, and AUC was slightly more than dose proportional. The median mitragynine Tmax was 1.0-1.3 h after single and 1.0-1.7 h after multiple doses; for 7-hydroxymitragynine Tmax, it was 1.2-1.8 h and 1.3-2.0 h. Steady-state mitragynine concentrations were reached in 8-9 days and 7-hydroxymitragynine within 7 days. The highest mean mitragynine T1/2 was 43.4 h after one and 67.9 h after multiple doses, and, for 7-hydroxymitragynine, it was 4.7 and 24.7 h. The mean 7-hydroxy-mitragynine/mitragynine concentration ratios were 0.20-0.31 after a single dose and decreased (0.15-0.21) after multiple doses. These mitragynine and 7-hydroxymitragynine data provide guidance for future clinical kratom dosing studies and an interpretation of clinical and forensic mitragynine and 7-hydroxymitragynine concentrations.

Pharmacokinetics, safety, and efficacy of tapentadol oral solution for treating moderate to severe pain in pediatric patients.

Background: This trial is part of the global pediatric clinical development program investigating the administration of the strong analgesic tapentadol in children and adolescents. Patients and methods: The single site, open-label phase 2 trial evaluated the pharmacokinetic profile of tapentadol and its major metabolite, tapentadol-O-glucuronide, as well as safety and tolerability and efficacy of a single dose of tapentadol oral solution (1 mg/kg) in patients (2 to <18 years) undergoing dental, ear, nose, or throat surgery. Blood sampling and pain intensity measurements were conducted using age-appropriate schedules and rating scales, respectively. Adverse events were monitored throughout the trial. Results: Sixty-six patients were treated. They were stratified by age: Group 1 (12 to <18 years), n=21; Group 2 (6 to <12 years), n=28; and Groups 3 (3 to <6 years) and 4 (2 to <3 years), n=17. Serum tapentadol concentrations observed in these pediatric patients were within the range observed in adults after administration of a single tapentadol immediate-release dose (50-100 mg), whereas those of the metabolite tapentadol-O-glucuronide were within the same range or lower than in adults who received comparable single doses of tapentadol. Pain intensity improved over time across all age groups. The most common treatment-emergent adverse events were nausea (24.2%), vomiting (16.7%), dizziness (9.1%), and headache (6.1%). Conclusion: A single dose of tapentadol oral solution (1 mg/kg) administered to pediatric patients (2 to <18 years) resulted in serum tapentadol concentrations within the targeted range shown to be safe and efficacious in adults. Tapentadol demonstrated good tolerability and safety; within the limitations of the trial design, improvements in postsurgical pain intensity were observed across the age groups. Tapentadol may provide a new treatment option in the management of moderate to severe pediatric pain.

Lemierre's disease: a case with bilateral iliopsoas abscesses and a literature review.

Lemierre's disease is characterized by sepsis, often with an oropharyngeal source, secondary septic emboli and internal jugular vein thrombosis (Lancet 1:701-3, 1936. Clin Microbiol Rev 20(4):622-59, 2007). Septic emboli affecting many bodily sites have been reported, including the lungs, joints, bones, and brain. The case report describes an unusual case of Lemierre's disease in a 64 year old gentleman causing profound sepsis, acute kidney injury, bilateral iliopsoas abscesses and a right hand abscess. To our knowledge, this is the first reported case of Lemierre's disease in the context of bilateral psoas abscesses, and highlights the ambiguity surrounding the definition of Lemierre's disease. The clinical literature review highlights the difficulty in definitively diagnosing the condition and offers some suggestions for recognising and refining the diagnostic criterion of Lemierre's.

Comparative pharmacokinetics and bioavailability of tapentadol following oral administration of immediate- and prolonged-release formulations.

OBJECTIVE: To evaluate the bioavailability and pharmacokinetics of orally administered tapentadol immediate release (IR) compared with tapentadol prolonged release (PR). METHODS: Three randomized, open-label, crossover studies were conducted in subjects under fasted conditions. Studies 1 and 2 determined the absolute bioavailability and pharmacokinetics of oral tapentadol IR 86 mg and tapentadol PR 86 mg, respectively, relative to a 34-mg intravenous (IV) dose of tapentadol. Study 3 determined the relative bioavailability of tapentadol PR 86 mg vs. tapentadol IR 86 mg. Pharmacokinetic parameters were calculated using non-compartmental analysis and relative bioavailability using dose-adjusted, log-transformed analysis of variance models for maximum concentration (Cmax) and areas under the serum concentration-time curve (AUC0-t and AUC). Adverse events (AEs), vital signs, 12-lead electrocardiograms (ECGs), and laboratory parameters were assessed. RESULTS: Absolute bioavailability was estimated to be 32% (95% confidence interval (CI), 29.4 - 34.8%; n = 24) for tapentadol IR 86 mg and 32% (95% CI, 28.0 - 35.9%; n = 18) for tapentadol PR 86 mg. Based on AUC, the relative bioavailability of tapentadol PR vs. tapentadol IR was 96% (90% CI, 87.8 - 104.4%; n = 16). Following IV administration, tapentadol had an elimination half-life of about 4 hours; in Studies 1 and 2, respectively, mean tapentadol volumes of distribution were 540 and 471 l, and mean clearance was 1,531 and 1,603 ml/min. Compared to tapentadol IR 86 mg, the prolonged-release characteristics of tapentadol PR 86 mg were evident with a lower Cmax (22.5 ng/ml vs. 64.2 ng/ml), a longer time to Cmax (5.0 h vs. 1.5 h), a higher half-value duration (HVD: 12.5 h vs. 3.6 h), and a longer mean residence time (MRT: 10.6 h vs. 6.0 h). The most common AEs reported were dizziness, headache, fatigue, nausea, somnolence, and dry mouth; most AEs were mild. No clinically relevant changes in vital signs, ECG parameters, or laboratory values were observed. CONCLUSIONS: Absolute bioavailability for both tapentadol IR and tapentadol PR was ~ 32% under fasted conditions. Extent of exposure (AUC) for tapentadol PR was very similar to tapentadol IR, whereas Cmax was lower and HVD/MRT longer for the prolonged-release formulation. Overall, the pharmacokinetic characteristics of tapentadol PR enable a twice-daily dosing regimen to be used; such a regimen is expected to improve patient compliance during chronic use.

Galantamine pharmacokinetics, safety, and tolerability profiles are similar in healthy Caucasian and Japanese subjects.

The aim of this study was to compare the pharmacokinetics of galantamine in healthy Japanese and Caucasian subjects and assess the safety and tolerability of galantamine in both ethnic groups. Parallel groups of healthy Japanese (n = 13; 6 males and 7 females)and Caucasian (n = 12; 6 males and 6 females) subjects matched for weight and age received single oral doses of galantamine 4 mg, or galantamine 8 mg, or placebo in a double-blind, three-way crossover trial according to a randomized dosing schedule. Concentrations of galantamine and norgalantamine were determined in plasma and urine samples taken up to 48 and 24 hours after dosing, respectively. Safety and tolerability were monitored throughout the trial by recording adverse events, laboratory tests, and cardiovascular parameters. The mean plasma concentration-time profiles of galantamine were very similar after single doses of galantamine (4 and 8 mg), and there was an approximate dose proportionality of galantamine pharmacokinetic parameters in both Caucasian and Japanese ethnic groups. The mean (+/- SD) pharmacokinetic parameters in the two ethnic groups did not show any clinically relevant differences. The ratios for the area under the plasma-concentration curve from time zero to infinity (AUC)0-infinity) in Japanese:Caucasian subjects with 4 and 8 mg doses were 103% (90% confidence interval [CII = 92-116) and 107% (90% CI = 94-121), respectively. Ratios for maximum plasma concentration (Cmax) values were 107% (90% CI= 90-127) and 108% (90% CI= 95-123), respectively. These ratios and associated 90% CIs were within the 80% to 125% range limit of bioequivalence. Analysis of variance (ANOVA) showed that these ratio values demonstrated no statistically significant difference between the two ethnic groups. There was no overt difference in the adverse event profile in Japanese subjects compared with Caucasian subjects. There were no serious adverse events, and no subjects discontinued from the study because of adverse events. No consistent or clinically relevant pattern of blood chemistry, hematology, or cardiovascular changes was seen. These results suggest that the pharmacokinetic profiles of galantamine after single-dose administration are not statistically significantly different between Caucasian and Japanese groups. Galantamine was well tolerated. The safety and tolerability of galantamine were very similar in the two ethnic groups.