Funded Projects

A recent FDA public meeting identified sleep disturbance as a primary contributor to opioid use disorder (OUD) treatment failure. Suvorexant (SUVO; Belsomra®) is a dual orexin receptor antagonist that is FDA-approved for insomnia, with low addiction liability, that improves sleep continuity with a single dose, has an extremely safe and mild side-effect profile, has clear interactions with the opioid system, and has not yet been evaluated in OUD patients. The hypothesis is that SUVO will improve total sleep time during withdrawal, have no addiction liability, and be more efficacious than trazodone, a common OUD-associated insomnia medication. Primary outcomes will be objective sleep measures and addiction liability. Secondary measures will include objective, biological, and self-report measures of opioid withdrawal severity, treatment retention, craving, and stress. Results will advance the treatment of OUD, the understanding of sleep and opioids, and the use of SUVO in clinical populations.

New medication treatment approaches are needed to help address the severe epidemic of opioid use disorder (OUD) and opioid overdose deaths in the U.S. Currently available medications, such as methadone, buprenorphine, and extended release injection naltrexone (XR-NTX; trade name: Vivitrol), are highly efficacious, but their effectiveness in practice is limited by poor adherence, with many patients stopping treatment prematurely and relapsing. The goal of this proposal is to develop an innovative long-acting subcutaneous implanted formulation of naltrexone, the O’Neil Long-Acting Naltrexone Implant (OLANI), toward FDA approval. Expected to produce naltrexone blood levels sufficient to block the effects of opioids for 6 months after implant, OLANI circumvents the need for adherence to monthly injections with XR-NTX and could represent an important new addition to the medical armamentarium for treatment of OUD.

Novel treatments for opioid use disorder are critically needed as the addiction and overdose crises continue. Neuromodulation is a promising supplemental treatment to standard care. The overarching project seeks to evaluate low-intensity focused ultrasound that targets the nucleus accumbens, a primary component of the brain’s reward neurocircuitry. This supplement will expand the number of participants in part of the study and will increase the project’s overall impact consistent with the original objectives and aims of the parent grant.

There are currently no FDA-approved treatments for cocaine use disorder (CUD) or co-occurring substance use disorder. High relapse rates pose a major obstacle to treatment, and this is due in part to the way that high drug cravings reduce individuals’ cognitive flexibility in situations where they are stressed or exposed to drug-related cues. These effects appear to be stronger in women with CUD than in men. Building on preliminary data that a drug called Guanfacine reverses these effects in women, but not in men, this 3-year pilot clinical study will test whether Guanfacine will reduce cocaine use and increase abstinence and will use laboratory challenges to determine whether it reduces cravings and enhances cognitive flexibility in stressful or drug-cue-related situations.

The ongoing opioid crisis has led to renewed concerns about the clinical prescription of addictive opioid analgesics. However, there are currently no suitable alternatives for treating severe or malignant pain. Studies of opioid signaling mechanisms in mice deficient in ?-arrestin have suggested that biased agonists displaying preferential activation of G-protein signaling over ?-arrestin signaling could offer a promising avenue for the development of opioid analgesics with a reduced adverse effects profile. However, there is no concluding evidence showing that such biased signaling can indeed be associated with reduced opioid side effects and, consequently, an improved safety profile. This research will address the need for preclinical data to rigorously evaluate this hypothesis with a program of in vivo studies to compare the effects of “balanced” opioids (morphine, oxycodone, and fentanyl) with that of the “biased” agonists PZM21 and two novel ligands provided by colleagues at the NIDA IRP in nonhuman primates. The results of these studies will provide critical information regarding the dependence liability of “biased” agonists that, in clinical practice, might be given on a repeated, or chronic, basis, potentially adding a powerful new tool for the safer management of severe or malignant pain.

Naltrexone (NTX) has been proven as an important, safe, and effective therapy in helping patients overcome opioid addition and in preventing overdose. Unfortunately, the therapeutic potential of NTX has been blunted by poor adherence. To combat this issue, a system must be developed to deliver NTX for longer durations than are currently available with a more patient-friendly format. The goal of this research is to optimize and scale up our laboratory PLGA-based microparticle formulations of NTX delivery (either 2 months or 7–10 days) and bridge it to a Phase 1 clinical trial. This innovation will result in a more patient-friendly format consisting of less painful injections and improved release kinetics. PLGA-based drug delivery systems have been used successfully in a number of small-molecule products and are the most widely utilized and studied biocompatible polymer systems in controlled release. Thus, the regulatory and development hurdles with the FDA will be lower than with other novel excipients or technologies. The significance of this research and product development is that the final outcome of this project will ultimately provide a new, readily viable, essential tool to help patients overcome opioid dependence.

Safe and effective options are urgently needed to prevent and treat opioid use disorder and polysubstance use disorders. Previous research in humans and animals suggests that activating the calcium-activated potassium channel KCa2.2 is a promising therapeutic approach for treating substance use disorders and associated health conditions. This project will perform a virtual high-throughput screen using novel machine learning approaches to discover new molecules that interact with the KCa2.2 channel. The newly discovered molecules help develop novel drugs for the treatment of opioid use disorder and associated health conditions.

MCAM is a novel opioid antagonist that can be used for opioid overdose reversal and has advantages over naloxone, including a pseudo-irreversible interaction with the ?-opioid receptor and a longer duration of action. Studies in animal models demonstrate MCAM’s long duration of action against the reinforcing and respiratory-depressant effects of remifentanil and heroin, indicating that could be a better treatment option for opioid use disorder. This project studies the pharmacodynamics of MCAM through animal toxicity and safety studies to establish the necessary and sufficient conditions from which to establish MCAM’s safety and antagonist activity in animals and humans. MCAM may be able to prevent all actions of any ?-receptor opioid drug in humans for a longer period of time than any other antagonist given acutely.

There is a need to develop a mu-opioid receptor (MOR) treatment with enhanced therapeutic effects and reduced undesirable effects. Recently, several highly selective and potent MOR modulators have been identified as novel leads for opioid use disorder treatment. They all showed more promising pharmacological profiles compared to other known drugs in this category. The current proposal will focus on further development of these leads for preclinical IND-enabling studies and dynamic drug discovery and development pipeline construction. This project plans to further validate therapeutic profiles of the current leads with self-administration and pharmacokinetic studies and expand the small-molecule library to build a dynamic drug discovery and development pipeline. Preclinical IND-enabling studies on the identified lead(s) will be conducted, and in vivo pharmacokinetics and pharmacodynamics profiles of the new hits will be compared with current leads to define the next generation of lead compound(s).

Although medications are available to treat opioid use disorder (OUD), adherence with treatment programs remains a problem. Nalmefene is an opioid receptor antagonist that was previously approved for treatment of opioid overdose–induced respiratory depression that has a longer duration of action than naloxone. AP007 is a unique formulation of nalmefene-loaded poly(lactic-co-glycolic acid) (PLGA) microparticles that when injected intramuscularly continually releases an effective dose of nalmefene and thus reduces opioid cravings in OUD patients. This group is developing AP007 and will have a lead formulation selected based on in vitro release kinetics data and in vivo pharmacokinetics data in rats. The objectives of the project are to determine safety and efficacy of AP007 in a swine opioid use/withdrawal model, preliminary safety in a first-in-human Phase 1 study, and preliminary efficacy in a Phase 2a multidose study. These results will be used to develop Phase 2 human and Phase 3 clinical studies.

This research will expand the understanding of the effects of non-invasive vagal nerve stimulation on patients with opioid use disorder by examining the relationship between nerve stimulation and treatment, respiratory physiology, withdrawal symptoms, and relapse. Additionally, these relationships will be added to existing algorithms and equipment being developed by the Inan Research Lab at the Georgia Institute of Technology. Collecting and determining the quality of conventional respiration signals, as well as collecting high-resolution impedance based respiratory measurements, will help to determine the impact of non-invasive vagal nerve stimulation on breathing and lung function in people with opioid use disorder, toward development of a profile of physiological effects of non-invasive vagal nerve stimulation during opioid withdrawal.