PAIN-OPIOID MECHANISMS

SUMMARY

1. Opioids work by binding to three receptor types (μ, δ, and κ) belonging to the G-protein receptor family.

2. Presynaptic effects of opioids decrease calcium into the cell, inhibiting subsequent release of excitatory neurotransmitters (serotonin, norepinephrine, substance P, and glutamate).

3. Postsynaptic effects include increasing potassium efflux, resulting in hyperpolarization of the neuron.

4. At the brainstem level, opioids inhibit GABAergic transmission, leading to excitation of descending inhibition.

5. Use long-acting agents to maintain consistent opioid serum levels. Advantages: convenient dosing schedules, more sustained analgesia, and uninterrupted sleep.

Reference(s)

Cifu, D.X. (2020). Braddom’s physical medicine and rehabilitation. Elsevier. Get it on Amazon.
Cuccurullo, S. (2019). Physical medicine and rehabilitation board review. New York: Demosmedical. Get it on Amazon.
O’Young, B., Young, M.A. and Stiens, S.A. (2008). Physical Medicine and Rehabilitation Secrets. Mosby. Get it on Amazon.