Opioid dependence is a severe issue globally. Despite the availability of pharmacological treatments for this disorder, the relapse rates remain high. To combat drug abuse and trafficking, a considerable amount of money and time has been spent, but for the distribution of drugs in markets, billions of dollars continue to flow into people’s pockets. This happens because the addicts supply money in massive amounts. The addicts even commit crimes due to lack of money for obtaining drugs.
The medications available for treating opioid dependence are naltrexone, methadone, and buprenorphine, which produce a therapeutic effect. There are many drawbacks to using these drugs, for example, their expensiveness, compliance problem, and diversion, although they have some therapeutic success. The practical, long-lasting, and inexpensive alternative treatment for opioid dependency is to develop a vaccine against it.
The vaccine development process is different from the development of drugs. The medications designed to target opioidergic receptors act pharmacologically, while vaccines work via pharmaco-kinetic antagonists. The vaccines stimulate the generation of drug-specific antibodies in the body when the drug is administered, so this restricts drugs from reaching the brain to have addictive effects. The development of vaccines against cocaine and nicotine has shown promising outcomes during clinical trials. The active immunisation with a vaccine based on stimulated antibody production has been successful in some studies. Also, it decreased self-intake of heroin in non-human primates, a study demonstrated by Bonese, et al, in the year1974. This study was a significant milestone in vaccines against drugs of abuse. It provided ample proof of efficacy and specificity with clinical aspects for several other narcotics like nicotine, cocaine, methamphetamine, besides opioids.
The number of drug-addiction cases is rising by the day in India. The number of criminal drug trafficking cases registered increased from seventy-thousand in 1990 to more than one million by the end of 2004. More than half of the Chinese citizens who have AIDS are drug users, and a similar pattern has been observed in India. A rise in occurrence of opioid associated fatal overdoses has been reported in Canada, America, and Europe. Other countries have also reported an upward trend in opioid-related disorders, like in many African countries. It was reported in the year 2016’s National Survey on Drug Utilisation and Health that 11.8 million people aged twelve and older had been misusing opioids in the past year in the United States. About 1.8 million people use drugs of abuse as a pain reliever, and 63, 362 died due to drug overdoses, of which 42,249 deaths were attributed to prescription narcoticopioids in 2016. It is predicted that opioid fatal overdoses are set to hike to 81,700 annually by 2025 in the United States alone.
Vaccines can offer a long-lasting, safe, and economical alternative to cure drug-addicted problems with a decreased overdose risk. The data of clinical trials from nicotine and cocaine vaccines suggests antibodies last for at least six months. The vaccines are not like opioid antagonists, where detoxification is needed before starting the vaccination, which offers another advantage over opioid antagonists. It has been seen that in Hepatitis-B and Influenza vaccines, the vaccine immunogenicity has not been affected during simultaneous opioid use in methadone-taking subjects. In another similar study, it was reported that the chronic administration of morphine through the use of osmotic minipumps did not affect the immunogenicity of an oxycodone vaccine. Various pre-clinical studies have demonstrated that existing opioid medication-assisted treatments (MAT) can be combined with vaccines like extended-release naltrexone, and naloxone.
Vaccines may provide a more comprehensive population coverage than MAT, which is restricted by admission regulation for outpatient prescriptions. As there is no vaccine available for illicit drugs in the market, it is expected that the cost will be low, and there might not be regulatory restrictions. There is no requirement for continuous dosing in the case of vaccines like that of small molecules. After the primary immunisation regimen, the antibodies are at maximum levels. Six months or year-wise boosts are expected to maintain adequate antibody levels, which is the best way to eradicate drug addiction globally.
The writer is a pharmacologist and PhD research student at Indian Institute of Technology (IIT), Ropar, Punjab.