<p>Pethidine is a phenylpiperidine derivative opioid analgesic. It acts mainly as mu-receptor agonist. Like most, opioid analgesics, it mimics endogenous opioids by activating opioid receptors in the central and peripheral nervous system. It reduces the release of neurotransmitter substances and also reduces the activity of postsynaptic neurons in the spinal cord thus preventing transmission of pain impulse.</p>