Alkermes’ Vivitrol likely be recommended for approval to treat opioid addiction

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Alkermes’ (NASDAQ:ALKS) Vivitrol is expected to receive a recommendation for approval from the FDA Psychopharmacologic Drugs Advisory Committee panel, pain experts told Pharmawire. The FDA does not have to follow the opinion of its advisors, but usually does. Most experts said the once-monthly dosing regimen would improve compliance and that the agent could capture significant market share. Additionally, it is unlikely that the panel will recommend approval with a stringent REMS.

The panel is scheduled to meet 16 September. The drug has a 12 October PDUFA date.

“In my opinion, it will be approved because simply there is no better drug at the moment available in the clinic for opioid addiction disorders,” said Anton Kolosov, a researcher at the Monash Institute of Medical Research, Centre for Pain Medicine & Palliative Care, Australia. Vivitrol is naltrexone, a drug that has been used routinely, albeit with medical supervision in rehab centers, where there is also an extensive support program for dealing with opioid dependence, he wrote in an e-mail. “It has been also successful in other forms of addiction, such as alcohol.”

Vivitrol is a monthly naltrexone injection to treat alcohol dependency. The FDA requires that it carries a Medication Guide.

Kolosov said Vivitrol generally poses some “insignificant” side effects like headaches and appetite loss but it can lead to serious health problems and even coma or death if used accidentally or deliberately with opioids. Therefore, “the patients taking it have to have a very strong predilection for self improvement and/or supervision by a medically qualified professional,” he said.

Currently approved treatments for opioid addiction are daily oral methadone and Reckitt Benckiser Pharmaceuticals’ (LOND:RB) Suboxone (buprenorphine HCl/naloxone HCl dihydrate).

A pain expert agreed the Vivitrol would likely be recommended for approval considering that naltrexone is widely used as an opioid antagonist in a variety of settings beyond addiction. By taking naltrexone, the mu-opioid receptors are blocked functionally, making them unavailable should a recovering addict take an opioid, he said. Hence, there is no “benefit” if the addict abuses again, he explained. He said his “gut reaction” is that a requirement for a REMS is less likely considering concerns are more around utility and efficacy than risk.

The Phase III data looks “encouraging,” the expert added. Once-monthly Vivitrol might be a relatively simple treatment compared to daily methadone and suboxone regimens, he said.

Dr Scott Glaser, who is on the board of the American Society of Interventional Pain Physicians, called the Phase II trial designs and results for Vivitrol “compelling.” He said the drug would fare “extremely well” in the market because the monthly sustained release formulation offers much better compliance as it does not rely on a patient to remember to take a pill. Still, he said that the panel may raise safety concerns regarding liver damage because the therapeutic window is much smaller. He also said the panel will likely have concerns about the treatment of acute pain in these patients since they would not be able to take opioids to alleviate such pain. If they did, it would lead to significant side effects, he explained.

It is not likely that Vivitrol will have a stringent REMS considering it is not part of the drug classes frequently subject to REMS and administration requires substantially less compliance on the patient’s part and dosing “significantly” enhances the medication’s safe use, said Glaser.

A second pain expert agreed the agency will likely approve the drug considering it does work in alcoholism rehab programs. However, uptake has fared poorly, he said. He added that the expense of the drug will could also limit its success.

Alkermes is currently indicated to treat alcohol addiction, and while the drug does work, it has not been a “major commercial success,” noted a drug consultant. He said Alkermes is hoping that the sales will increase with the addition of an opioid indication. Yet, as an injectable, it may not be patient preferred, he said. Also, while the once-monthly treatment is a better dosing regimen than current treatment options, it still can be difficult to ensure patients are compliant, he said. “You can schedule an injection but having people come into a doctor’s office is another story,” he said.

Vivitrol had net sales of USD 6.2m for the quarter ended 30 June, compared to USD 4.2m for the same period the previous year.

Alkermes declined to comment but a spokesperson said in a previous story that Alkermes has heard anecdotally that doctors are already prescribing Vivitrol for off-label use of opioid addiction.

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