Can we initiate Gabapentin (Gabapentin) therapy with 150 mg twice daily (bid) in an elderly patient with potential sensitivity, underlying medical conditions, or impaired renal function, rather than starting with 300 mg at bedtime?

Gabapentin Initiation: 150 mg BID vs 300 mg at Bedtime

Yes, you can absolutely start gabapentin at 150 mg twice daily (300 mg total daily dose) instead of 300 mg at bedtime, and this approach is explicitly supported by guideline recommendations, particularly for elderly patients or those with potential sensitivity concerns. 1

Guideline-Supported Starting Options

The Mayo Clinic guidelines provide two equally acceptable initial dosing strategies for gabapentin 1:

• Option 1: 100-300 mg at bedtime
• Option 2: 100-300 mg three times daily

Your proposed 150 mg twice daily (300 mg total daily) falls within the acceptable starting range and offers a middle ground between these two approaches.

Why 150 mg BID is Appropriate

Lower starting doses and slower titration are specifically recommended in geriatric patients to minimize adverse effects. 1 The FDA label confirms that gabapentin may be initiated as 300 mg on Day 1,600 mg/day (300 mg twice daily) on Day 2, and 900 mg/day (300 mg three times daily) on Day 3, demonstrating that divided dosing from the outset is acceptable. 2

Starting with 150 mg BID provides several advantages:

• Reduces initial sedative burden by spreading the dose across the day rather than concentrating it at bedtime 1
• Allows assessment of tolerability before advancing to higher doses 1
• Minimizes fall risk from dizziness and somnolence, which are dose-dependent adverse effects occurring in approximately 19% and 14% of patients respectively 3

Critical Titration Principles

Gabapentin has nonlinear, saturable absorption pharmacokinetics, requiring careful gradual titration. 1 After starting at 150 mg BID:

• Increase by 100-300 mg every 1-7 days as tolerated 1
• Target therapeutic dose is 1800-3600 mg/day in three divided doses 1, 2
• Allow 3-8 weeks for titration plus 2 weeks at maximum tolerated dose to properly evaluate efficacy 1
• An adequate trial may require 2 months or more 1

Mandatory Renal Function Assessment

You must calculate creatinine clearance using the Cockcroft-Gault equation before initiating therapy, as gabapentin is renally excreted and elderly patients invariably have reduced renal function. 3 This is non-negotiable in elderly patients, as age-related decline in renal function is often masked by normal serum creatinine due to reduced muscle mass. 4

For creatinine clearance 30-59 mL/min, the FDA recommends starting doses of 200-300 mg twice daily maximum. 2 For creatinine clearance 15-29 mL/min, dosing should be 200-300 mg once daily. 2

Common Pitfalls to Avoid

• Never start at high doses without gradual titration (such as 800 mg QID), as this dramatically increases the risk of intolerable adverse effects, particularly in elderly patients 3
• Do not assume lack of efficacy if adequate time for titration and therapeutic trial has not been allowed—efficacy develops gradually over several weeks 5
• Never abruptly discontinue—taper gradually over a minimum of 1 week if stopping therapy 2
• Do not use once-daily or twice-daily dosing long-term for standard gabapentin, as three times daily administration is essential due to saturable absorption once therapeutic doses are reached 5
• Maximum time between doses should not exceed 12 hours 2

Expected Adverse Effects

Dizziness (19%), somnolence (14%), peripheral edema (7%), and gait disturbance (9%) are the most common adverse effects. 3 These are typically mild to moderate, dose-dependent, and often transient, usually subsiding within approximately 10 days. 3 Research demonstrates a clear dose-response relationship for falls or fractures, with highest risk at doses ≥2,400 mg/day. 6