Extended-release intramuscular naltrexone

Preoperative Management of Opioid and Nonopioid Analgesics: Society for Perioperative Assessment and Quality Improvement (SPAQI) Consensus Statement

There is a lack of guidelines for preoperative dosing of opioid and nonopioid pain medications for surgical patients, which can lead to suboptimal preoperative pain control. The Society for Perioperative Assessment and Quality Improvement identified preoperative dosing of opioid and nonopioid analgesics as an area in which consensus could improve patient care. The aim of this guideline is to provide consensus that will allow perioperative physicians to make optimal recommendations regarding preoperative pain medication dosing. Six categories of pain medications were identified: opioid agonists, opioid antagonists, opioid agonist-antagonists, acetaminophen, muscle relaxants, and triptans/headache medications. We then used a Delphi survey technique to develop consensus recommendations for preoperative dosing of individual medications in each of these groups.

Opioid Addiction: Social Problems Associated and Implications of Both Current and Possible Future Treatments, including Polymeric Therapeutics for Giving Up the Habit of Opioid Consumption

BACKGROUND

Detoxification programmes seek to implement the most secure and compassionate ways of withdrawing from opiates so that the inevitable withdrawal symptoms and other complications are minimized. Once detoxification has been achieved, the next stage is to enable the patient to overcome his or her drug addiction by ensuring consumption is permanently and completely abandoned, only after which can the subject be regarded as fully recovered.

METHODS

A systematic search on the common databases of relevant papers published until 2016 inclusive.

RESULTS AND CONCLUSION

Our study of the available oral treatments for opioid dependence has revealed that no current treatment can actually claim to be fully effective. These treatments require daily oral administration and, consequently, regular visits to dispensaries, which in most cases results in a lack of patient compliance, which causes fluctuations in drug plasma levels. We then reviewed alternative treatments in the available scientific literature on polymeric sustained release formulations. Research has been done not only on release systems for detoxification but also on release systems for giving up the habit of taking opioids. These efforts have obtained the recent authorization of polymeric systems for use in patients that could help them to reduce their craving for drugs.

Extended-release intramuscular naltrexone (VIVITROL®): a review of its use in the prevention of relapse to opioid dependence in detoxified patients

Naltrexone is a μ-opioid receptor antagonist that blocks the euphoric effects of heroin and prescription opioids. In order to improve treatment adherence, a once-monthly, intramuscular, extended-release formulation of naltrexone (XR-NTX) [VIVITROL(®)] has been developed, and approved in the USA and Russia for the prevention of relapse to opioid dependence, after opioid detoxification. The clinical efficacy of this formulation in patients with opioid dependence was demonstrated in a 24-week, randomized, double-blind, placebo-controlled, multicentre, phase III trial (ALK21-013; n = 250). In this trial, opioid-detoxified patients receiving XR-NTX 380 mg once every 4 weeks, in combination with psychosocial support, had a significantly higher median proportion of weeks of confirmed opioid abstinence during weeks 5-24, compared with those receiving placebo (primary endpoint). A significantly higher proportion of patients receiving XR-NTX achieved total confirmed abstinence during this period than those receiving placebo. XR-NTX was also associated with a significantly greater reduction in opioid craving and a significantly longer treatment retention period than placebo. XR-NTX was generally well tolerated in the phase III trial. The most common (incidence ≥5 %) treatment-emergent adverse events that also occurred more frequently with XR-NTX than with placebo were hepatic enzyme abnormalities, nasopharyngitis, insomnia, hypertension, influenza and injection-site pain. Thus, XR-NTX is a useful treatment option for the prevention of relapse to opioid dependence, following opioid detoxification.

Clinical implications of exenatide as a twice-daily or once-weekly therapy for type 2 diabetes

Exenatide (exendin-4) is a 39-amino acid peptide belonging to the glucagon-like peptide-1 (GLP-1) receptor agonist class that has been demonstrated to improve glycemic control in patients with type 2 diabetes mellitus. Exenatide can be injected twice daily (ExBID) before meals or once weekly (ExQW) when encompassed within dissolvable poly-(D,L-lactide-co-glycolide) microspheres. The primary difference between these formulations is the plasma concentration of exenatide over time, with the long-acting form providing continuous delivery. Clinical trials have examined the similarities and differences in the efficacy and safety/tolerability outcomes of these formulations. In 2 clinical studies spanning 24 and 30 weeks, significant (P < 0.05) reductions from baseline were observed in fasting plasma glucose (ExBID, -12 and -25 mg/dL; ExQW, -35 and -41 mg/dL), postprandial glucose (ExBID, -124 mg/dL; ExQW, -95 mg/dL), and glycated hemoglobin (HbA1c) (ExBID, -0.9% and -1.5%; ExQW, -1.6% and -1.9%). Reductions in body weight from baseline were significant and similar with both treatments (ExBID, -1.4 and -3.6 kg; ExQW, -2.3 and -3.7 kg). Reductions in systolic blood pressure from baseline were observed with both formulations, particularly in patients who were hypertensive at baseline. Beneficial improvements in lipid profiles were small and fluctuated in significance. Patients reported greater treatment satisfaction with ExQW compared with ExBID dosing. Gastrointestinal adverse events were commonly observed with both formulations but were less frequent with ExQW. These events were of mild-to-moderate intensity and rarely led to discontinuation. Real-world data for ExBID demonstrated decreases in HbA1c, fasting plasma glucose, and body weight that were consistent with clinical trial results. Cases of pancreatitis or renal impairment have been reported in patients treated with ExBID, although no causal relationship with treatment has been shown. This review describes the similarities and differences between exenatide delivered as a twice-daily or as a once-weekly injection to provide a better understanding of the clinical effects and potential clinical uses of each.

Encapsulation of exenatide in poly-(D,L-lactide-co-glycolide) microspheres produced an investigational long-acting once-weekly formulation for type 2 diabetes

Exenatide once-weekly (EQW [2 mg s.c.]) is under development as monotherapy as an adjunct to diet and exercise or as a combination therapy with an oral antidiabetes drug(s) in adults with type 2 diabetes. This long-acting formulation contains the active ingredient of the original exenatide twice-daily (EBID) formulation encapsulated in 0.06-mm-diameter microspheres of medical-grade poly-(D,L-lactide-co-glycolide) (PLG). After mechanical suspension and subcutaneous injection by the patient, EQW microspheres hydrate in situ and adhere to one another to form an amalgam. A small amount of loosely bound surface exenatide, typically less than 1%, releases in the first few hours, whereas drug located in deeper interstices diffuses out more slowly (time to maximum, ~2 weeks). Fully encapsulated exenatide (i.e., drug initially inaccessible to diffusion) releases over a still longer period (time to maximum, ~7 weeks) as the PLG matrix hydrolyzes into lactic acid and glycolic acid, which are subsequently eliminated as carbon dioxide and water. For EQW, plasma exenatide concentrations reach the therapeutic range by 2 weeks and steady state by 6-7 weeks. This gradual approach to steady state seems to improve tolerability, as nausea is less frequent with EQW than EBID. EQW administrations may be associated with palpable skin nodules that generally resolve without further medical intervention. In comparative trials, EQW improved hemoglobin A1c more than EBID, sitagliptin, pioglitazone, or insulin glargine and reduced fasting plasma glucose more than EBID. Weight loss due to EQW or EBID was similar. EQW is the first glucose-lowering agent that is administered once weekly.

Thermosensitive Pluronic hydrogel: prolonged injectable formulation for drug abuse

Objective:

The main objective of this study was to investigate thermosensitive Pluronic^® F-127 (PF-127) hydrogel for the modified release of a potent alcohol and opioid antagonist, naltrexone (NTX) hydrochloride, in a subcutaneous injectable dosage form.

Methods:

The NTX hydrogels were prepared by the cold method, and the in vitro release profiles of various formulations were evaluated at 37°C using the Franz diffusion cell system. We examined the different PF-127 concentrations, pH of solution, and inorganic salts on drug release from these gels.

Results:

The data showed an increase in PF-127 content from 20% to 35%, resulting in a decrease in the rate of NTX release. Among the formulations prepared in different pH solutions, pH 7.4 produced the slowest drug release rate. The addition of inorganic salts had no significant effect on drug release. However, these factors appeared to have limited effects on drug release rate. Therefore, to achieve a sustained-release formulation, a NTX and triacetyl β-cyclodextrin (TAβCD) complex was evaluated. The binary systems of NTX/TAβCD in different molar ratios were prepared by the kneading method, and complex formation was demonstrated by differential scanning calorimetry.

Conclusion:

The results of the current in vitro study indicate that PF-127 gel formulations containing drug complexes with hydrophobic cyclodextrin could be useful for the preparation of a controlled delivery system of water-soluble drugs such as NTX, for a period of more than 140 hours.

Unplanned admissions to two Sydney public hospitals after naltrexone implants

OBJECTIVE

To describe hospital presentations related to the use of naltrexone implants, an unlicensed product used in Australia for treating heroin dependence.

DESIGN

Retrospective case file audit.

SETTING

Two Sydney teaching hospitals.

PATIENTS

Identified through referrals to Drug and Alcohol Consultation-Liaison services over a 12-month period, August 2006 to July 2007.

MAIN OUTCOME MEASURES

Diagnosis, management and duration of admission.

RESULTS

Twelve cases were identified: eight were definitely or probably related to naltrexone implants or the implantation procedure (rapid detoxification). Of these, six patients had severe opiate withdrawal and dehydration, with an average hospital stay of 2.3 days. One patient had an infection at the implant site, and one an underlying anxiety disorder requiring psychiatric admission. Three patients had analgesia complications, and one had unrelated cardiac arrhythmia.

CONCLUSIONS

These severe adverse events challenge the notion that naltrexone implants are a safe procedure and suggest a need for careful case selection and clinical management, and for closer regulatory monitoring to protect this marginalised and vulnerable population.

Sustained-release naltrexone for opioid dependence

BACKGROUND

Naltrexone is an opioid antagonist which effectively blocks heroin effects. Since opioid dependence treatment with naltrexone tablets suffers from high dropout rates, several depot injections and implants are under investigation. Sustained-release formulations are claimed to be effective, but a systematic review of the literature is lacking.

OBJECTIVES

To evaluate the effectiveness of sustained-release naltrexone for opioid dependence and its adverse effects in different study populations.

SEARCH STRATEGY

The following databases were searched from their inception to November 2007: Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, CINAHL, LILACS, PsycINFO, ISI Web of Science, trial database at http://clinicaltrials.gov, available NIDA monographs, CPDD and AAAP conference proceedings. The reference lists of identified studies, published reviews and relevant web sides were searched manually. Study authors and drug companies were contacted to obtain any unpublished material or missing data.

SELECTION CRITERIA

To evaluate effectiveness only RCTs were included. To evaluate safety, any clinical trial reporting adverse effects was assessed. Treatment condition was extended to include alcohol dependent subjects and healthy volunteers.

DATA COLLECTION AND ANALYSIS

Reviewers independently evaluated the reports, rated methodological quality and extracted data. Analyses were performed separately for opioid dependent, alcohol dependent and healthy participants.

MAIN RESULTS

Foe effectiveness, one report met inclusion criteria. Two dosages of naltrexone depot injections (192 and 384 mg) were compared to placebo. High-dose significantly increased days in treatment compared to placebo (WMD 21.00, 95% CI 10.68 to 31.32, p<0.0001). High-dose compared to low-dose significantly increased days in treatment (WMD 12.00, 95% CI 1.69 to 22.31, p=0.02). Number of patients retained in treatment did not show significant differences between groups. For adverse effects, seventeen reports met inclusion criteria analyses, six were RCTs. Side effects were significantly more frequent in naltrexone depot groups compared to placebo. In alcohol dependent samples only, adverse effects appeared to be significantly more frequent in the low-dose naltrexone depot groups compared to placebo (RR 1.18, 95% CI 1.02 to 1.36, p=0.02). In the opioid dependent sample, group differences were not statistically significant. Reports on systematic assessment of side effects and adverse events were scarce.

AUTHORS' CONCLUSIONS

There is insufficient evidence to evaluate the effectiveness of sustained-release naltrexone for treatment of opioid dependence. For naltrexone injections, administration site-related adverse effects appear to be frequent, but of moderate intensity and time limited. For a harm-benefit evaluation of naltrexone implants, more data on side effects and adverse events are needed.