Opioid addiction is caused by the use of illicit substances such as heroin or opium, as well as the misuse of prescription medications like hydromorphone, morphine, hydrocodone, oxycodone, fentanyl, methadone, buprenorphine, and codeine.¹

Global prevalence of opioid addiction

In 2021, ~39.5 million individuals struggled with opioid addiction. While most opioid-dependent individuals opt for illicit heroin, the use of prescription opioids is on the rise, contributing to a substantial 70% of the global burden of disease associated with illicit drug use in 2015.^2,3

Prevalence of opioid addiction in South Africa

Between 2012 and 2017, ~20 000 South Africans were admitted to public hospitals for opioid use disorder (OUD). These patients were predominantly male, aged between eight- and 86-years (mean age 27). The majority were of African descent, followed by those of Coloured ancestry, and a significant portion were unemployed. In the private sector, OUD prevalence was ~0.1% between 2011 and 2020.⁴

Drivers of increased OUD in South Africa

In South Africa, OUD was historically prevalent in affluent communities but has expanded to rural and socio-economically disadvantaged areas. This shift is attributed to the availability of cheaper heroin derivatives like nyaope, often smoked with cannabis, which has created new drug markets. This transformation significantly contributes to the escalating opioid use in the country.⁴

High-risk groups for OUD

In South Africa, men, young adults in their twenties, and individuals with co-morbid psychiatric disorders or other substance use disorders are at high risk of developing OUD.⁴

Why do people become addicted to opioids?

Dependence and substance abuse is a product of biological, environmental, genetic, and psychosocial factors. Opioids can deceive both the brain and the body into perceiving the drug as essential for survival. As individuals develop tolerance to their prescribed doses, they may require higher amounts of medication to alleviate pain or achieve a sense of euphoria, ultimately leading to dependency. The nature of addiction is intricate, involving multiple pathways in the brain, making it a complex phenomenon.^5,6

Treatment of opioid addiction

Opioid addiction therapy aims to provide a safer substitute for illicit opioids and to ease the detoxification process. Common treatment approaches include maintenance therapy, detoxification, and antagonist therapy. Maintenance treatment employs μ-opioid agonists or partial agonists to occupy receptor sites, preventing withdrawal symptoms upon discontinuing illicit opioids and blocking the binding of illicit opioids to μ-receptors, thereby preventing euphoria. The World Health Organization recommends methadone and buprenorphine for maintenance therapy, alongside psychosocial support, and treatment with naltrexone.^1,2

What is naltrexone and how does it work?

Naltrexone is a competitive μ-opioid receptor antagonist with minimal agonistic properties. It effectively blocks both the pleasurable and physiological effects of opioid agonists. Importantly, it does not lead to the development of dependence or tolerance over time, and discontinuation does not result in withdrawal symptoms. Naltrexone, when administered orally, undergoes first-pass metabolism, converting into active (6-β naltrexol) and inactive metabolites. This metabolism is substantial, as evidenced by the rapid peak levels of naltrexone and its metabolites approximately one hour after oral dosing. The serum half-life for chronic oral administration is around 10 hours, and compared to naloxone, another μ-opioid antagonist, naltrexone has a longer half-life, enabling it to block the agonistic effects of other opioids for up to 48 hours. After oral administration, the half-life is four hours. Naltrexone is primarily excreted by the kidneys as a metabolite and unchanged drug.⁷

Effectiveness of naltrexone

Naltrexone is often combined with an α-2 agonist to minimise patient discomfort and shorten withdrawal duration. Rapid opiate detoxification using naltrexone and clonidine has demonstrated completion rates ranging from 75% to 81%, compared to 40% for methadone and clonidine alone. To treat OUD, naltrexone can be initiated at lower doses of 25mg daily for a few days before being increased to 50mg daily, 100mg every other day, 150mg every third day, or as a 380mg depot injection for monthly administration.⁷

The consequences of not treating drug addiction

In 2019, ~600 000 people died due to drug use, with ~80% of these deaths associated with opioid use. About 25% of deaths were due to overdoses. Opioid addiction accounted for nearly 28 million years of disability-adjusted life years lost as a result of premature death and disability caused by drug use. Of those years lost, 17 million were attributable solely to drug use disorders across all drug types. After adjusting for various factors, OUD is associated with a 7.63-year shorter life expectancy.^2,4,8

References

1. Kjome KL, Moeller FG. Long-Acting Injectable naltrexone for the Management of patients with Opioid Dependence. Substance Abuse: Research and Treatment, 2011.
2. World Health Organization. Opioid overdose. Available at: https://www.who.int/news-room/fact-sheets/detail/opioid-overdose#:~:text=Worldwide%2C%20about%20296%20million%20people,disorders%20in%202021(2).
3. Harker N, et al. Is South Africa being spared the global opioid crisis? A review of trends in drug treatment demand for heroin, nyaopeand codeine-related medicines in South Africa (2012–2017). International Journal of Drug Policy, 2020.
4. Tlalia M, et al. Diagnosis and treatment of opioid use disorder in a South African private sector medical insurance. 2023. [Internet]. Available at: https://www.medrxiv.org/content/10.1101/2022.04.28.22274253v1.full.pdf
5. American Society of Anesthesiologists. Opioid Abuse. [Internet]. Available at: https://www.asahq.org/madeforthismoment/pain-management/opioid-treatment/opioid-abuse/
6. Dydyk AM, Jain NK, Gupta M. Opioid Use Disorder. [Updated 2023 Jul 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK553166/
7. Singh D, Saadabadi A. [Updated 2023 May 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available at: https://www.ncbi.nlm.nih.gov/books/NBK534811/
8. United Nations Office on Drugs and Crime. World Drug Report 2017 (ISBN: 978-92-1-148291-1, eISBN: 978-92-1-060623-3, United Nations publication, Sales No. E.17.XI.6). Available at: https://www.unodc.org/wdr2017/field/Booklet_2_HEALTH.pdf