Designing opioids that deter abuse

Kappa opioid agonists reduce oxycodone self-administration in male rhesus monkeys

RATIONALE

Combinations of mu and kappa opioid receptor (KOR) agonists have been proposed as potential analgesic formulations with reduced abuse liability. The current studies extend previous work by investigating the typical KOR agonist, salvinorin A, and the atypical KOR agonist, nalfurafine, as deterrents of oxycodone self-administration using a progressive ratio (PR) schedule of reinforcement.

METHODS

In separate experiments, adult male rhesus monkeys (N = 4/experiment) were trained under a PR schedule of reinforcement to self-administer cocaine (0.1 mg/kg/injection) and saline on alternating days. Oxycodone (0.01-0.1 mg/kg/injection) alone and combined with salvinorin A (experiment 1; 0.006, 0.012 mg/kg/injection) or nalfurafine (experiment 2; 0.0001-0.00032 mg/kg/injection) were tested within the alternating cocaine and saline baseline. The mechanism of nalfurafine's effects on oxycodone self-administration was investigated via pretreatment with the KOR antagonist, nor-binaltorphimine (nor-BNI; 10 mg/kg; i.m.).

RESULTS

All subjects self-administered oxycodone alone above saline levels at sufficiently large doses, and combining salvinorin A or nalfurafine with oxycodone reduced the mean number of injections per session to saline levels (experiment 1) or to levels that were significantly lower than oxycodone alone (experiment 2). The ability of nalfurafine to reduce oxycodone self-administration was reversed by pretreatment with nor-BNI.

CONCLUSIONS

These results demonstrate that KOR agonists, including the clinically used KOR agonist, nalfurafine, can punish self-administration of a prescription opioid analgesic, oxycodone, in rhesus monkeys and that nalfurafine's punishing effect is KOR-dependent. Combinations of KOR agonists with prescription opioids may have reduced abuse liability.

Risk based in vitro performance assessment of extended release abuse deterrent formulations

High strength extended release opioid products, which are indispensable tools in the management of pain, are associated with serious risks of unintentional and potentially fatal overdose, as well as of misuse and abuse that might lead to addiction. The issue of drug abuse becomes increasingly prominent when the dosage forms can be readily manipulated to release a high amount of opioid or to extract the drug in certain products or solvents. One approach to deter opioid drug abuse is by providing novel abuse deterrent formulations (ADF), with properties that may be viewed as barriers to abuse of the product. However, unlike regular extended release formulations, assessment of ADF technologies are challenging, in part due to the great variety of formulation designs available to achieve deterrence of abuse by oral, parenteral, nasal and respiratory routes. With limited prior history or literature information, and lack of compendial standards, evaluation and regulatory approval of these novel drug products become increasingly difficult. The present article describes a risk-based standardized in-vitro approach that can be utilized in general evaluation of abuse deterrent features for all ADF products.

A Guide for Pain Management in Low and Middle Income Communities. Managing the Risk of Opioid Abuse in Patients with Cancer Pain

Most patients who present with cancer have advanced disease and often suffer moderate to severe pain. Opioid therapy can be safe and effective for use in cancer patients with pain, but there are rightful concerns about inappropriate opioid use even in the cancer population. Since cancer patients live longer than ever before in history (and survivors may have long exposure times to opioid therapy), opioid misuse among cancer patients is an important topic worthy of deeper investigation. Cancer patients with pain must be evaluated for risk factors for potential opioid misuse and aberrant drug-taking behaviors assessed. A variety of validated screening tools should be used. Of particular importance is the fact that pain in cancer patients changes frequently, whether it is related to their underlying disease (progression or remission), pain related to treatment (such as painful chemotherapy-induced peripheral neuropathy), and concomitant pain unrelated to cancer (such as osteoarthritis, headache, or back pain). Fortunately, clinicians can use universal precautions to help reduce the risk of opioid misuse while still assuring that cancer patients get the pain therapy they need. Another important new “tool” in this regard is the emergence of abuse-deterrent opioid formulations.

Medical cost savings associated with an extended-release opioid with abuse-deterrent technology in the US

OBJECTIVES

In the US, prescription opioids with technology designed to deter abuse have been introduced to deter drug abuse without hindering appropriate access for pain patients. The objective of this study was to estimate changes in medical costs following the introduction of a new formulation of extended-release (ER) oxycodone HCl (oxycodone) with abuse-deterrent technology in the US.

METHODS

Health insurance claims data were used to estimate changes in rates of diagnosed opioid abuse among continuous users of extended-release opioids (EROs) following the introduction of reformulated ER oxycodone in August 2010. This study also calculated the excess medical costs of diagnosed opioid abuse using a propensity score matching approach. These findings were integrated with published government reports and literature to extrapolate the findings to the national level. All costs were inflated to 2011 US dollars.

RESULTS

The introduction of reformulated ER oxycodone was associated with relative reductions in rates of diagnosed opioid abuse of 22.7% (p < 0.001) and 18.0% (p = 0.034) among commercially-insured and Medicaid patients, respectively. There was no significant change among Medicare-eligible patients. The excess annual per-patient medical costs associated with diagnosed opioid abuse were $9456 (p < 0.001), $10,046 (p < 0.001), and $11,501 (p < 0.001) for commercially-insured, Medicare-eligible, and Medicaid patients, respectively. Overall, reformulated ER oxycodone was associated with annual medical cost savings of ∼$430 million in the US.

LIMITATIONS

Because of the observational research design of this study, caution is warranted in any causal interpretation of the findings. Portions of the study relied on prior literature, government reports, and assumptions to extrapolate the national medical cost savings.

CONCLUSIONS

This study provides evidence that reformulated ER oxycodone has been associated with reductions in abuse rates and substantial medical cost savings. Payers and policy-makers should consider these benefits as they devise and implement new guidelines and policies in this therapeutic area.