title: Relative bioavailability of a newly developed 5-mg levomethadone hydrochloride IR tablet (L-Polamidon® 5 mg tablets) in comparison with the 5-mg levomethadone hydrochloride oral solution (L-Polamidon® solution for substitution) as reference product.
abstract: OBJECTIVE
  To establish the relative bioavailability (rBA) between two p.o. 5-mg levomethadone hydrochloride formulations, i.e., L-Polamidon® 5 mg tablets (test) vs. L-Polamidon® solution for substitution (reference). To assess the safety and tolerability of both formulations.
  
  
  METHODS
  A total of 33 healthy male subjects, aged 29 ± 6 years (BMI: 23.9 ± 2.5 kg/m2) completed this single center, open-label, randomized, 2-period cross-over study with single dose administrations under fasting conditions and coadministration with naltrexone for safety reasons. Administrations of both investigational products were separated by a washout period of at least 2 weeks, i.e., 13 treatmentfree days. The total dose for each subject was 2 x 5 mg resulting in 10 mg levomethadone hydrochloride. For pharmacokinetic evaluation, blood samples were withdrawn until 72 hours postdose. A validated non-stereoselective liquid chromatography-tandem mass spectroscopy method (LC-MS/MS) was applied for the determination of levomethadone in plasma. The lower limit of quantitation was 0.100 ng/mL. Adverse events were descriptively analyzed in the study population.
  
  
  RESULTS
  The geometric means of the parameters related with the extent of total exposure of levomethadone, i.e., AUC(0-tlast) and AUC(0-∞), were 244.422 ng x h/mL and 332.999 ng x h/mL for test and 246.837 ng x h/mL and 329.467 ngÃh/mL for reference, respectively. The geometric means of the peak exposure for levomethadone, i.e., Cmax, were 8.923 ng/mL for test and 8.635 ng/mL for reference. The point estimates (PEs) of the Test/Reference (T/R) adjusted geometric mean ratios of AUC(0-last), AUC(0-∞), and C(max) were 99.20%, 101.42%, and 104.11%, respectively, and all of them showed 90%-confidence intervals (CIs) within the range of 80.00 - 125.00% as suggested by regulatory requirements for bioequivalence assessment In total, 21 subjects experienced 55 AEs during the study, the most frequently reported AE, i.e., headache, accounted for 13 out of the total 55 AEs (23.6%) and no AEs of severe intensity were reported.
  
  
  CONCLUSIONS
  Bioequivalence could be demonstrated in terms of rate and extent of absorption after administration of test and reference products under naltrexone protection. Concerning the safety evaluation, no negative implications on the possible use of the test formulation could be determined.
authors: Henning H
authors: HH
authors: Blume
authors: Ralf-Steven
authors: RS
authors: Wedemeyer
authors: Frank
authors: F
authors: Donath
authors: Katrin
authors: K
authors: Roscher
authors: Gerd
authors: G
authors: Elvert
authors: Daniel
authors: D
authors: Wagner
authors: Oliver
authors: O
authors: Bley
authors: Alexander
authors: A
authors: Vuia
authors: Marina
authors: M
authors: Todorova-Sanjari
authors: Ramon
authors: R
authors: Villalobos
authors: Barbara
authors: B
authors: Schug
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000009:adverse effects / Q000097:blood / Q000737:chemistry / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001682:Biological Availability; D002626:Chemistry, Pharmaceutical; D002853:Chromatography, Liquid; D018592:Cross-Over Studies; D005858:Germany; D006801:Humans; D008297:Male; D008691:Methadone / Q000008:administration & dosage* / Q000009:adverse effects / Q000097:blood / Q000737:chemistry / Q000493:pharmacokinetics*; D019999:Pharmaceutical Solutions; D013607:Tablets; D053719:Tandem Mass Spectrometry; D055815:Young Adult
chemical_list: D000701:Analgesics, Opioid; D019999:Pharmaceutical Solutions; D013607:Tablets; D008691:Methadone