Pharmacokinetic-pharmacodynamic analysis of drug liking blockade by buprenorphine subcutaneous depot (CAM2038) in participants with opioid use disorder.

Buprenorphine is used to treat opioid use disorder (OUD). Weekly and monthly subcutaneous long-acting buprenorphine injections (CAM2038) provide more stable buprenorphine plasma levels and reduce the treatment burden, misuse, and diversion associated with sublingual transmucosal buprenorphine formulations. To characterize the pharmacokinetic/pharmacodynamic (PK/PD) relationship, a maximum inhibition (Imax) model was developed relating CAM2038 buprenorphine plasma concentration to drug liking maximum effect (Emax) visual analog scale (VAS; bipolar) score after intramuscular hydromorphone administration. Data included time-matched observations of buprenorphine plasma concentration and drug liking Emax VAS score after hydromorphone 18 mg administration in 47 non-treatment-seeking adults with moderate to severe OUD in a phase 2 study. Analysis used non-|linear mixed-effects modeling (NONMEM®). The final Imax model adequately described the PK/PD relationship between buprenorphine plasma concentration and drug liking Emax VAS score. Simulations showed drug liking was effectively blocked at low buprenorphine plasma concentrations (0.4 ng/mL) where the upper 95% confidence interval of the drug liking Emax VAS score was below the pre-defined 11-point complete blockade threshold. The buprenorphine plasma concentration required to achieve 90% of the maximal effect (IC90) of drug liking was 0.675 ng/mL. Interindividual variability in responses to buprenorphine was observed; some participants experienced fluctuating responses, and a few did not achieve drug liking blockade even with higher buprenorphine plasma concentrations. This affirms the need to individualize treatment and titrate doses for optimal treatment outcomes. PK/PD models were also developed for desire to use VAS and Clinical Opiate Withdrawal Scale (COWS) scores, with results aligned to those for drug liking.

Population Pharmacokinetic Analysis Supports Initiation Treatment and Bridging from Sublingual Buprenorphine to Subcutaneous Administration of a Buprenorphine Depot (CAM2038) in the Treatment of Opioid Use Disorder.

BACKGROUND AND OBJECTIVE: In treating opioid use disorder (OUD), subcutaneous (SC) extended-release buprenorphine (BPN) depots, e.g., CAM2038, have been shown to provide smaller and less frequent fluctuations in BPN plasma concentrations and pharmacodynamic responses, improve outcomes, reduce treatment burden, and lower risks of misuse and diversion compared to daily sublingual (SL) BPN. This analysis characterized the pharmacokinetics (PK) of BPN following intravenous and SL administration, and administration of SC CAM2038 weekly and monthly. METHODS: Pharmacokinetic data from two Phase 1 and two Phase 2 trials in healthy participants and participants with OUD, respectively, were used to develop a population PK model using non-linear mixed effects modelling. The analysis included data from 252 participants and 10,658 BPN observations. RESULTS: The disposition of BPN was best described by a three-compartment model with first-order elimination, and absorption of SL BPN and SC CAM2038 weekly and monthly by dual parallel absorption pathways. Model diagnostics indicated good predictive performance of BPN concentrations. Buprenorphine plasma concentration-time profiles were simulated for treatment initiation, switching from SL BPN to CAM2038 weekly and monthly, and tapering after interrupting treatment with CAM2038. Simulations predicted CAM2038 weekly and monthly doses that provided BPN plasma maximum concentration (Cmax) and trough concentration (Ctrough) values at steady state within those observed following SL BPN administration. CONCLUSIONS: This population PK model supports the use of CAM2038 doses as individualized treatment for OUD across different treatment stages, including initiation, switching from SL BPN according to established dose conversion schedules, and tapering. TRIAL REGISTRATIONS: ISRCTN41550730 (05/19/2014), ISRCTN24987553 (07/29/2014), NCT02611752 (11/23/2015), NCT02710526 (03/16/2016).

Pharmacokinetic Evaluation of Once-Weekly and Once-Monthly Buprenorphine Subcutaneous Injection Depots (CAM2038) Versus Intravenous and Sublingual Buprenorphine in Healthy Volunteers Under Naltrexone Blockade: An Open-Label Phase 1 Study.

INTRODUCTION: CAM2038 q1w (once weekly) and q4w (once monthly) are investigational buprenorphine subcutaneous (SC) formulations based on FluidCrystal® injection depot technology. These two drug products are being developed for opioid dependence treatment, with a target for once-weekly and once-monthly SC dosing. The rationale for developing two products with different dosing frequencies is that treatment strategies/routines, and hence different treatment preferences, can vary between patients, different stages of opioid maintenance treatment, and countries. This study evaluated the pharmacokinetics and safety of buprenorphine and norbuprenorphine following administration of CAM2038 q1w or q4w versus active controls. METHODS: Healthy volunteers were randomized to five treatment groups. All received a single intravenous dose of buprenorphine 600 µg, followed post-washout by a single dose of CAM2038 q4w 96 mg, a single dose of CAM2038 q4w 192 mg, or sublingual buprenorphine 8, 16, or 24 mg daily for 7 days, followed post-washout by a single dose of CAM2038 q4w 64 or 128 mg or four repeated weekly doses of CAM2038 q1w 16 mg. All subjects received daily naltrexone. RESULTS: Eighty-seven subjects were randomized. Median buprenorphine t max after CAM2038 q4w was 4-10 h (24 h for CAM2038 q1w); mean terminal half-life was 19-25 days (5 days for CAM2038 q1w). CAM2038 q4w showed dose-proportional buprenorphine release, with similar exposure to repeat-dose CAM2038 q1w at comparable monthly dose level. Both CAM2038 formulations showed complete absolute bioavailability of buprenorphine and 5.7- to 7.7-fold greater buprenorphine bioavailability versus sublingual buprenorphine. CAM2038 q1w and q4w were well tolerated; subjects' acceptance was higher for CAM2038 than for sublingual buprenorphine 1 h post-dose. CONCLUSIONS: The pharmacokinetic profiles of CAM2038 q1w and q4w versus sublingual buprenorphine support expected treatment efficacy with once-weekly and once-monthly dosing, respectively. CAM2038 formulations were safe and showed good local tolerability. TRIAL REGISTRATION: ISRCTN24987553. FUNDING: Camurus AB.

Transient paradoxical bronchospasm associated with inhalation of the LAMA AZD9164: analysis of two Phase I, randomised, double-blind, placebo-controlled studies.

BACKGROUND: AZD9164 has demonstrated potential as an inhaled, long-acting, muscarinic antagonist (LAMA) bronchodilator. However, in patients with COPD, but not in healthy subjects, a transient initial drop in FEV1 was observed following inhalation of nebulised doses of AZD9164 in citrate buffer.Two additional studies were conducted to further assess the safety and tolerability of multiple ascending doses of AZD9164 in 27 white and 18 Japanese healthy subjects and in 4 patients with COPD. In these studies, AZD9164 was inhaled via Turbuhaler™. METHODS: These were Phase I, randomised, double-blind, placebo-controlled, multiple ascending dose (MAD) studies conducted in Sweden and UK. Healthy subjects (mean age 25.9 yrs) and patients with COPD (mean age 66 yrs, mean post-bronchodilator FEV1 60.1% predicted normal value) were randomised 2:1 to active treatment (400, 1000 or 2800 µg delivered doses of AZD9164) or placebo. RESULTS: No safety or tolerability concerns were identified in the healthy subjects at doses up to and including 2800 µg and both studies confirmed the bronchodilator effect of AZD9164. However, the first 3 patients in the COPD cohort who received AZD9164 (1000 µg) experienced a transient fall in FEV1 5 to 15 minutes after inhalation of AZD9164 while the patient receiving placebo did not. The study safety review process then resulted in cessation of further activities on AZD9164. Retrospective analysis showed that two healthy subjects had also had transient falls in FEV1 shortly after inhalation of AZD9164 400 and 2800 µg respectively, although neither reported any related respiratory symptoms or other AEs. CONCLUSIONS: These results show that transient paradoxical bronchoconstriction can occur in some healthy subjects, in addition to patients with COPD, following inhalation of AZD9164 and that the citrate buffer used in the nebulised formulation cannot have been the only cause of the drop in FEV1 in previous studies. As preclinical data do not provide an explanation, the reasons for this brief post-dose drop in FEV1 remain unclear. However, these results highlight the importance of monitoring lung function immediately post-dose when investigating novel inhaled treatments, even when a rapid onset of effect is not expected. TRIAL REGISTRATION: Clinicaltrials.gov NCT01016951 and NCT01096563.

Exposure of infants to budesonide through breast milk of asthmatic mothers.

BACKGROUND: Maintenance treatment with inhaled corticosteroids is often required for asthmatic nursing women. Data on the transfer of inhaled corticosteroids from plasma to breast milk and the subsequent exposure of the breast-feeding infant has been unavailable. OBJECTIVE: We sought to assess budesonide concentrations in milk and plasma of asthmatic nursing women receiving maintenance treatment with the Pulmicort Turbuhaler and estimate the exposure of their breast-fed infants. METHODS: Milk and plasma samples were collected up to 8 hours after dosing from 8 mothers receiving budesonide maintenance treatment (200 or 400 microg twice daily). Pharmacokinetic parameters were calculated from budesonide milk and plasma concentrations. Infant exposure was estimated based on average milk budesonide concentrations. A single blood sample was obtained from 5 infants close to expected infant maximum concentration. RESULTS: Budesonide concentrations in milk reflected those in maternal plasma, supporting passive diffusion of budesonide between plasma and milk, and was always lower than that in plasma. The mean milk/plasma ratio was 0.46. The estimated daily infant dose was 0.3% of the daily maternal dose for both dose levels, and the average plasma concentration in infants was estimated to be 1/600th of the concentrations observed in maternal plasma, assuming complete infant oral bioavailability. Budesonide concentrations in infant plasma samples were all less than the limit of quantification. CONCLUSION: Maintenance treatment with inhaled budesonide (200 or 400 microg twice daily) in asthmatic nursing women results in negligible systemic exposure to budesonide in breast-fed infants. CLINICAL IMPLICATIONS: These data support continued use of inhaled budesonide during breast-feeding.

Lung deposition and efficacy of inhaled formoterol in patients with moderate to severe COPD.

BACKGROUND: Little is known about the impact of COPD on lung deposition of inhaled drugs and the relationship between lung-dose and response of pulmonary function measurements. METHODS: Nineteen patients with varying degrees of COPD were randomized to inhale single doses of formoterol (Oxis) Turbuhaler 4.5, 9, 18, and 36 microg in a double blind, placebo-controlled, crossover design. Urinary excreted formoterol during 32 h was used to determine absolute lung deposition. Peak inspiratory flow (PIF) and inhaled volume (IV) were recorded to assess the patients' ability to use Turbuhaler. Efficacy was measured by spirometry, inspiratory capacity (IC), airway conductance (sG(AW)), and absolute lung volumes. RESULTS: Mean pulmonary bioavailability of formoterol was about 24% of the nominal delivered dose after inhalation for the different treatments. No significant correlations between lung deposition and baseline FEV(1), PIF or IV were shown. All formoterol doses produced statistically significant increases in FEV(1), FVC, IC, and sG(AW) relative to placebo. Linear dose/response relationships were observed for these variables, with more narrow limits of the slopes for the lung-dose/response relationships than for the nominal-dose/response relationships. Moreover, 36 and 18 microg formoterol statistically significantly decreased functional residual capacity (FRC) and residual volume (RV) relative to placebo. CONCLUSIONS: This study could not show any difference in lung deposition of formoterol inhaled via Turbuhaler between patients with moderate and severe COPD. Moreover, the effect of formoterol on various pulmonary function measurements were more closely related to lung deposition than the inhaled nominal dose.