Selected neuropathic analgesic dosing regimens
AGENT | INITIAL DOSE | TITRATION | DOSE RANGE | ADVERSE EFFECTS | ADDITIONAL INFORMATION |
---|---|---|---|---|---|
Anticonvulsants | |||||
• Gabapentin | 100–300 mg/d | Increase by 100–300 mg/d every wk | 300–1200 mg 3 times/d | Drowsiness, dizziness, peripheral edema, visual blurring | Dosage adjustments required in renal failure and in elderly patients |
• Pregabalin | 25–150 mg/d | Increase by 25–150 mg/d every wk | 150–300 mg twice daily | Drowsiness, dizziness, peripheral edema, visual blurring | Similar adjustments in renal failure |
• Carbamazepine | 100 mg/d | Increase by 100–200 mg/d every wk | 200–400 mg 3 times/d | Drowsiness, dizziness, blurred vision, ataxia, headache, nausea, rash | Drug of first choice for idiopathic trigeminal neuralgia; as an enzyme inducer, it might interfere with activity of other drugs such as warfarin; monitoring of blood counts and liver function recommended |
TCAs | |||||
• Amitriptyline, nortriptyline, or desipramine | 10–25 mg/d | Increase by 10 mg/d every wk | 10–100 mg/d | Drowsiness, confusion, orthostatic hypotension, dry mouth, constipation, urinary retention, weight gain, arrhythmia | Amitriptyline more likely to produce drowsiness and anticholinergic side effects; contraindicated in patients with glaucoma, symptomatic prostatism, and substantial cardiovascular disease |
SNRIs | |||||
• Venlafaxine | 37.5 mg/d | Increase by 37.5 mg/d every wk | 150–225 mg/d | Nausea, dizziness, drowsiness, hyperhidrosis, hypertension | Dosage adjustments required in renal failure |
• Duloxetine | 30 mg/d | Increase by 30 mg/d every wk | 60–120 mg/d | Sedation, nausea, constipation, ataxia, dry mouth | Contraindicated in patients with glaucoma |
Controlled-release opioids* | |||||
• Morphine | 15 mg every 12 h | NA | NA | Nausea, vomiting, sedation, dizziness, urinary retention, constipation | Constipation requires concurrent bowel regimen; monitor for overdose, effectiveness, tolerance, dependence, and appropriateness |
• Oxycodone | 10 mg every 12 h | NA | NA | ||
• Fentanyl | 12 µg/h (patch) | NA | NA | ||
• Hydromorphone | 3 mg every 12 h | NA | NA | ||
Others | |||||
• Tramadol | 50 mg/d | Increase by 50 mg/d every wk | 50–100 mg 4 times/d or 100–400 mg/d (controlled release) | Ataxia, sedation, constipation, seizures, orthostatic hypertension | Might lower seizure threshold; use with caution in patients with epilepsy |
• Tapentadol (controlled release) | 50 mg every 12 h | Increase by 50 mg/dose every wk | Maximum dose 500 mg in 24 h | Nausea, constipation, somnolence, dizziness, vomiting, fatigue | Contraindicated in patients with creatinine clearance < 0.5 mL/s/m2 and Child-Pugh class C. Caution in those at risk of seizure |
• Lidocaine | NA | NA | 5% patches or gel applied to painful areas for 12 h in a 24-h period | NA | Most useful for postherpetic neuralgia; has virtually no systemic side effects; lidocaine patches not available in Canada |
• THC or nabiximols | 1–2 sprays every 4 h, maximum 4 sprays on day 1 | NA | 2 sprays 4 times/d | Dizziness, fatigue, nausea, euphoria | Approved in Canada for neuropathic pain associated with multiple sclerosis; causes positive urine drug test results for cannabinoids; monitor application site (oral mucosa) |
• Nabilone | 0.25–0.5 mg at night (owing to side effects of drowsiness and fatigue) | Increase by 0.5 mg/d every wk | 3 mg twice daily | Dizziness, drowsiness, dry mouth | Approved in Canada for nausea and vomiting associated with chemotherapy. Does not cause positive test results for cannabinoids on routine urine drug testing |
NA—not available, SNRI—serotonin-norepinephrine reuptake inhibitor, TCA—tricyclic antidepressant, THC—tetrahydrocannabinol.
↵* Opioid initial dosing recommendations are for healthy opioid-naïve adults; opioid titration and dose range are not included owing to variability of patient and pain factors.
Adapted with permission from Moulin et al.7