Side Effects of Nefopam
Nefopam use can be associated with several significant side effects including tachycardia, glaucoma, seizures, and delirium, though it has advantages over other analgesics by having no detrimental effects on hemostasis, gastric mucosa, renal function, hepatic function, vigilance, ventilatory drive, and intestinal motility. 1
Common Side Effects
- Tachycardia - one of the most frequently reported cardiovascular effects 1
- Sweating - commonly reported and likely related to its anticholinergic properties 2, 3
- Nausea and vomiting - gastrointestinal effects that may limit tolerability 2, 3
- Dizziness and headache - neurological effects that may impact patient comfort 3
- Anticholinergic effects - including dry mouth and urinary retention 3, 4
Serious Neuropsychiatric Side Effects
- Seizures - can occur unpredictably and are not dose-related; may progress to status epilepticus in some cases 1, 5
- Confusion and hallucinations - significant neuropsychiatric effects that may require discontinuation 3
- Delirium - particularly concerning in critically ill or elderly patients 1
- Agitation and aggressive behavior - reported in cases of abuse or high-dose usage 4
Cardiovascular Effects
- Palpitations - reported alongside tachycardia as common cardiovascular effects 3
- Angina - rare but documented cardiovascular adverse effect 3
- Cardiac conduction abnormalities - reported in overdose cases 6
Rare but Serious Adverse Effects
- Fatal overdose - though rare, cases have been reported with symptoms including cardiac arrest 6
- Cerebral edema - reported in overdose situations 6
- Fever and renal failure - documented in severe toxicity cases 6
- Myoclonus and tremor - particularly with high doses or abuse 4
Risk Factors and Special Considerations
- History of epilepsy - nefopam may lower seizure threshold and is contraindicated in epileptic patients 3
- Concomitant use with tricyclic antidepressants - may further lower seizure threshold 3
- Potential for abuse - cases of dependence and abuse have been documented with escalating doses and withdrawal symptoms 4
- Depressive symptoms during withdrawal - reported in patients who developed dependence 4
Comparison to Other Analgesics
- Unlike NSAIDs (e.g., ketorolac), nefopam has no detrimental effects on hemostasis, gastric mucosa, or renal function 1
- Unlike acetaminophen, nefopam has no detrimental effects on hepatic function 1
- Unlike opioids, nefopam has no detrimental effects on vigilance, ventilatory drive, and intestinal motility 1
- When used appropriately, nefopam may serve as an effective alternative or adjunctive analgesic for ICU patients, potentially reducing opioid requirements 1
Clinical Recommendations
- Nefopam should be used with caution in patients with a history of seizures or those on medications that lower seizure threshold 5, 3
- Monitor for cardiovascular effects, particularly tachycardia, which is a common side effect 1
- Be aware of potential for abuse and dependence, particularly with prolonged use 4
- Consider nefopam as part of a multimodal analgesic approach to reduce opioid requirements in appropriate patients 1
- Recognize that nefopam is not available in the United States and Canada but is used in nearly 30 other countries 1