Analgesics

Pharmacology2026-10-22Updated 2026-10-231 min read

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Pain pathway and drug targets

Stage	Main event	Drug examples
Transduction	Injury activates peripheral nociceptors	NSAIDs, local anesthetics
Transmission	Impulses travel along sensory nerves	Local anesthetics
Modulation	Signals are modified in spinal cord and brainstem	Opioids, selected antidepressants
Perception	Pain becomes consciously experienced	Opioids and centrally acting analgesics

Major analgesic classes

Class	Mechanism	Key adverse effects
NSAIDs	COX inhibition reduces prostaglandin synthesis	GI injury, renal effects, bleeding risk
Paracetamol	Predominantly central analgesic/antipyretic actions	Liver toxicity in overdose
Opioids	Activate opioid receptors, especially μ	Respiratory depression, constipation, sedation
Local anesthetics	Block voltage-gated sodium channels	CNS and cardiac toxicity if systemic exposure is excessive
Antidepressants	Modulate descending pain pathways	Depend on drug; anticholinergic effects or blood-pressure changes may occur
Gabapentinoids	Bind α₂δ subunits of voltage-gated calcium channels	Dizziness, sedation, edema

Dental relevance: NSAIDs are useful for inflammatory dental pain when suitable; paracetamol is an alternative or adjunct. Choose according to the patient's medical history and contraindications.