GABACARE-NT TAB

• Neuropathic pain responds poorly to ordinary analgesics; these two agents act on the nerve pathways generating the pain instead.
• Gabapentin binds to calcium channel subunits in the central nervous system, reducing the abnormal nerve signalling that causes burning and shooting pain.
• Nortriptyline, a tricyclic, enhances descending inhibitory pain pathways — an established mechanism in neuropathic pain independent of its antidepressant effect.
• The two act by different mechanisms, so the combination is often effective where either alone is insufficient, at lower doses of each.
• Nortriptyline taken at night can also improve the disturbed sleep that accompanies chronic nerve pain.

Not everyone gets these. Most are mild and settle as the course finishes.

• Causes marked drowsiness and dizziness, particularly when starting or increasing the dose. The patient must not drive or operate machinery until the effect is known.
• Never stop gabapentin abruptly after regular use — taper under supervision to avoid withdrawal symptoms and, rarely, seizures.
• Contraindicated shortly after myocardial infarction, in significant arrhythmia and heart block, and in known QT prolongation because of the nortriptyline.
• Do not give with, or within fourteen days of, a monoamine oxidase inhibitor.
• Gabapentin combined with opioids causes profound sedation and respiratory depression; avoid or use with close monitoring.
• Use with particular caution in the elderly, who are more susceptible to confusion, falls, urinary retention and postural hypotension.
• Contraindicated in narrow-angle glaucoma and urinary retention; dose reduction is required in renal impairment as gabapentin is renally cleared.
• Antidepressants can increase suicidal ideation, particularly in younger patients — monitor mood, and avoid alcohol entirely.