Can I use a combination of pregabalin (75 mg) with nortriptyline (10 mg) at bedtime and vitamin B12 (1500 mcg) once daily for 2 weeks to manage burning feet symptoms in a 21-year-old male patient who developed symptoms after taking levofloxacin (750 mg) for a urinary tract infection (UTI)?

Management of Fluoroquinolone-Induced Neuropathy

For a 21-year-old male with burning feet after levofloxacin exposure, a combination of pregabalin 75 mg and nortriptyline 10 mg at bedtime plus vitamin B12 1500 mcg daily for 2 weeks is an appropriate initial treatment strategy, with reassessment after this period to determine if continued therapy or neurological referral is needed.

Understanding Fluoroquinolone-Induced Neuropathy

Fluoroquinolones like levofloxacin can cause peripheral neuropathy as an adverse effect, typically presenting as burning sensations in the extremities. This is a recognized complication that can occur even after a single dose of the medication.

Treatment Approach

First-Line Medications

1. Pregabalin (75 mg at bedtime)

   • Gabapentinoids are first-line agents for neuropathic pain
   • Starting at a low dose (75 mg) is appropriate to minimize side effects
   • Pregabalin has advantages over gabapentin including easier titration and more predictable pharmacokinetics 1

2. Nortriptyline (10 mg at bedtime)

   • Tricyclic antidepressants are effective first-line treatments for neuropathic pain
   • Low-dose nortriptyline (10 mg) is appropriate as a starting dose, especially in younger patients
   • Combination with pregabalin provides synergistic effects by targeting different pain pathways 1

3. Vitamin B12 (1500 mcg daily)

   • While there is insufficient evidence to support the routine use of vitamins for neuropathic pain 2, B12 supplementation is low-risk and may be beneficial in cases where deficiency could be contributing to symptoms

Treatment Duration and Monitoring

• Initial 2-week trial is reasonable to assess response
• If symptoms improve, continuing for an additional 2 weeks is appropriate
• If no improvement occurs, referral for neurological evaluation and nerve conduction studies is warranted

Rationale for This Approach

1. Combination therapy targeting different mechanisms:

   • Pregabalin acts on calcium channels to reduce neurotransmitter release
   • Nortriptyline inhibits serotonin and norepinephrine reuptake
   • This combination may provide better pain relief than monotherapy 1

2. Appropriate dosing:

   • Starting with low doses minimizes side effects while providing therapeutic benefit
   • The 75 mg pregabalin dose is below the maximum recommended dose (600 mg/day) 3
   • The 10 mg nortriptyline dose is within the recommended range (10-75 mg/day) for neuropathic pain 1

3. Time-limited approach with clear follow-up plan:

   • 2-week initial trial allows assessment of response
   • Plan for either continuation or referral based on response

Potential Side Effects and Monitoring

Pregabalin

• Monitor for dizziness, somnolence, and peripheral edema
• Low starting dose minimizes these risks

Nortriptyline

• Watch for anticholinergic effects (dry mouth, constipation)
• Low dose reduces risk of these effects
• Caution regarding doses >100 mg/day due to increased risk of cardiac events 1

Alternative Approaches

If this combination is not effective after 2 weeks:

1. Consider dose adjustment (increasing pregabalin to 150 mg)
2. Proceed with neurological referral for nerve conduction studies
3. Consider alternative agents such as duloxetine or gabapentin if specialized care is not immediately available

Conclusion

The proposed regimen of pregabalin 75 mg + nortriptyline 10 mg at bedtime with vitamin B12 1500 mcg daily represents a rational, evidence-based approach for initial management of fluoroquinolone-induced neuropathy, with appropriate follow-up planning based on treatment response.