Gabapentin and Memantine

Gabapentin and memantine are medications used for various neuro-ophthalmic conditions, particularly nystagmus and neuropathic pain. They work through different mechanisms but are often used for similar purposes.

Gabapentin

How It Works

Gabapentin modulates calcium channels in the nervous system, reducing abnormal nerve signaling.

Uses in Neuro-Ophthalmology

• Acquired pendular nystagmus
• Neuropathic pain
• Oscillopsia
• Superior oblique myokymia

Dosing

• Start low (100-300mg at bedtime)
• Increase gradually
• Typical range: 300-1200mg three times daily
• Higher doses may be needed

Side Effects

• Drowsiness
• Dizziness
• Swelling of legs
• Weight gain
• Fatigue

Memantine

How It Works

Memantine is an NMDA receptor antagonist, modulating glutamate activity in the brain.

Uses in Neuro-Ophthalmology

• Acquired pendular nystagmus
• Often combined with gabapentin
• Some evidence for downbeat nystagmus

Dosing

• Start at 5mg daily
• Increase weekly
• Typical target: 10-20mg twice daily
• Slow titration important

Side Effects

• Dizziness
• Headache
• Confusion (especially in elderly)
• Constipation

Combination Therapy

Gabapentin and memantine are often used together for nystagmus, as they work through different mechanisms and may have additive effects.

Monitoring

• Kidney function (both drugs cleared by kidneys)
• Watch for excess sedation
• Monitor for effectiveness

Frequently Asked Questions

How quickly will these help my nystagmus?

Effects may be seen within days to weeks, though optimal dosing may take longer to achieve. Not all patients respond, and the degree of improvement varies.

Can I drive while taking these?

Both medications can cause drowsiness and dizziness, especially initially. Don't drive until you know how the medication affects you. Discuss with your doctor.

Are these habit-forming?

Gabapentin has some potential for dependence with prolonged use, though it's generally not highly addictive. Memantine is not habit-forming.