1. Definition of opioids
Opioids are chemicals that bind to opioid receptors (ORs) in the central and peripheral nervous systems. These receptors modulate pain, stress and emotions. Opioids include natural substances (such as morphine and codeine), semi-synthetic compounds (such as oxycodone), and synthetic opioids (such as fentanyl). They are mainly used for their powerful analgesic properties.
Note: Our body also produces endogenous opioids, playing important roles in pain management and emotion modulation, such as dynorphins, enkephalins, endorphins and nociceptins.
2. Brief history of opioid use
The use of opioids dates back millennia, with mentions in ancient texts from Mesopotamia, Egypt, and Greece. Used medicinally since the 3rd millennium BC. B.C., opium played a central role in various cultures for its medicinal and recreational properties. In the 19th century, morphine, codeine and later heroin were isolated from opium. The 20th century saw the emergence of synthetic opioids, developed for specific medical uses.
3. Types of opioids
3.1 Natural opioids
Natural opioids are found primarily in the opium poppy. Morphine, extracted from opium, is used to treat severe acute and chronic pain. Codeine, found in lower concentrations in opium, is used to treat mild to moderate pain and as a cough suppressant. Thebaine, although not used directly as a medicine, is used to produce semi-synthetic opioids.
3.2 Semi-synthetic opioids
Semi-synthetic opioids are manufactured by chemically modifying natural opioids to optimize their therapeutic effectiveness and reduce unwanted side effects. Common examples include oxycodone, hydrocodone, and heroin. These substances pose a high risk of dependence and abuse.
3.3 Synthetic opioids
Synthetic opioids are made entirely in a laboratory. Fentanyl, extremely potent, is used for the management of severe pain. Methadone is used to treat severe chronic pain and in substitution treatment programs. Tramadol, less potent than morphine, treats moderate to severe pain. Sufentanil, even more powerful than fentanyl, is used mainly in anesthesia.
4. Mechanisms of action of opioids
4.1 How do opioids affect the nervous system?
Opioids bind to opioid receptors in the central and peripheral nervous systems, inhibiting the transmission of pain signals and changing the brain's perception of pain.
4.2 Receptors involved and biochemical effects
The main opioid receptors are mu (μ), delta (δ) and kappa (κ) receptors. Their activation inhibits the transmission of pain signals, reducing neuronal excitability and the release of neurotransmitters, thus producing the analgesic effect.
5. Risks and side effects of opioids
5.1 Dependence and tolerance
Prolonged use of opioids can lead to physical and psychological dependence, as well as tolerance requiring increasing doses to achieve the same effects.
5.2 Overdose and intoxication
An opioid overdose can cause severe and potentially fatal respiratory depression. Signs include slow or irregular breathing and loss of consciousness.
5.3 Other side effects
Opioids can cause constipation, nausea, drowsiness, confusion, hallucinations and itching.
6. Public health issues
6.1 Epidemic of opioid abuse
Opioid abuse is a major public health crisis, particularly in North America, with a dramatic increase in cases of addiction and overdoses.
6.2 Statistics and impact on public health
Opioid overdose deaths have increased fivefold since 1999 in the United States. In 2019, more than 70% of overdose deaths involved an opioid.
6.3 Preventive measures and regulations
Measures include patient and healthcare professional education, responsible prescribing and addiction treatment programs.
7. Treatment for opioid addiction
7.1 Treatment approaches
Treatment combines medical, psychological and social interventions to reduce dependence and improve patients' quality of life.
7.2 Substitution therapies
Substitution therapies use medications such as methadone, buprenorphine, and naltrexone to stabilize the patient and reduce withdrawal symptoms.
7.3 Psychological support and rehabilitation
Psychological support and rehabilitation includes cognitive behavioral therapies, group therapies and residential rehabilitation programs.
8. Opioid Addiction Treatment
8.1 Research and development of new analgesics
Research focuses on developing less addictive and safer painkillers, as well as controlled delivery technologies.
8.2 Control and prevention policies
Policies aim to balance access to pain treatments while reducing abuse and addiction, through monitored prescribing programs and improved education of health professionals.
9. Conclusion
9.1 Summary of key points
Opioids, while effective in relieving pain, pose significant risks of addiction and overdose. Their use must be carefully managed, and the current public health crisis highlights the importance of preventative strategies and regulatory measures.
9.2 Thoughts on the future of opioids
The future lies in the development of new, less addictive and safer analgesics, as well as rigorous control and prevention policies. Continued research and innovations in treatments will provide better options for pain management.