How many hours will Pregabalin 75mg and Nortriptyline 10mg provide relief to peripheral neuropathy patients?

Duration of Pain Relief from Pregabalin 75mg and Nortriptyline 10mg in Peripheral Neuropathy

Pregabalin 75mg and nortriptyline 10mg will typically provide pain relief for 8-12 hours per dose, with full therapeutic effect developing over 2-4 weeks of consistent treatment. 1

Onset and Duration of Action

Pregabalin (75mg)

• Initial onset: Pain reduction can begin within 24 hours of first dose 2
• Duration per dose: 8-12 hours (requiring twice daily dosing) 1
• Full effect timeline:
  • 1 full point reduction on pain scale: Day 1-6
  • 2 full points reduction: Day 13-17
  • 3 full points reduction: Day 23-30 2

Nortriptyline (10mg)

• Initial onset: 1-2 weeks for noticeable effect
• Duration per dose: 12-24 hours (typically dosed once daily at bedtime) 3
• Full effect timeline: 4-6 weeks with at least 2 weeks at maximum tolerated dosage 3

Dosing Considerations

Current Doses vs. Therapeutic Doses

• Pregabalin: 75mg is a sub-therapeutic starting dose

  • Recommended starting dose: 150mg/day 1
  • Effective therapeutic dose: 300-600mg/day 3, 1
  • NNT for 300mg/day: 5.99
  • NNT for 600mg/day: 4.04 (more effective) 1

• Nortriptyline: 10mg is an appropriate starting dose

  • Typical therapeutic range: 25-100mg/day 3
  • Usually started at 10-25mg at bedtime 3

Combination Therapy Benefits

The combination of pregabalin and nortriptyline offers several advantages:

1. Complementary mechanisms of action: Different pain pathways targeted 3
2. Enhanced efficacy: Combination therapy shows greater pain relief than either medication alone 3
3. Lower doses needed: May achieve pain relief with lower doses of each medication, potentially reducing side effects 3

Optimizing Pain Relief Duration

To maximize duration of pain relief:

1. Dose optimization:

   • Increase pregabalin to 150-300mg/day (divided doses) 1
   • Gradually titrate nortriptyline to 25-75mg/day 3

2. Dosing schedule:

   • Pregabalin: Twice daily dosing (morning and evening)
   • Nortriptyline: Once daily dosing at bedtime to minimize daytime sedation 3

Common Side Effects to Monitor

• Pregabalin: Dizziness (29-35%), somnolence (16-25%), peripheral edema, weight gain 1
• Nortriptyline: Dry mouth, constipation, urinary retention, blurred vision (anticholinergic effects) 3

Pitfalls and Caveats

1. Underdosing: The current pregabalin dose (75mg) is likely insufficient for optimal pain relief. Studies show significantly better outcomes with doses of 150-600mg/day 4

2. Delayed efficacy assessment: Full therapeutic effect of nortriptyline takes 4-6 weeks; avoid premature discontinuation 3

3. Elderly patients: Start with lower doses and titrate more slowly; monitor for cognitive impairment and sedation 1

4. Renal impairment: Pregabalin dosing should be adjusted based on creatinine clearance 1

5. Abrupt discontinuation: Both medications should be tapered gradually to avoid withdrawal symptoms

In conclusion, while the current doses will provide some relief, they are likely suboptimal, particularly for pregabalin. For maximum duration and quality of pain relief, dose optimization according to guidelines would be recommended.