Table 1.

Comparison of pharmacokinetics and dosage.^37–39

	Gabapentin	Pregabalin
Tmax (hours)	2–3	1
t1/2 (hours)	5–7	5.5–6.7
Bioavailability	27–60%	>90%
Pharmacokinetics	Nonlinear (zero-order)	Linear
Plasma protein binding	<3%	Assumed to be zero
Potency at the α2δ1 subunit	+	++
Metabolism	Nil	Very limited if any metabolism occurs. Some patients may have scant N-methylation
Renal excretion	100% unchanged	92–99% unchanged
Suggested dosing schedule	Three or four times daily/	Two or three times daily
Usual dose	900–3600 mg/day	150–600 mg/day
Time to effective dose using recommended titrations	14 days	5–7 days
Gabapentin dosing in renal impairment (creatinine clearance, mL/min)
50–79	600–1800 mg/day in three divided doses
30–49	300–900 mg/day in three divided doses
15–29	150–600 mg/day (150 mg daily dose to be given as 300 mg in three divided doses on alternate days)
<15	150–300 mg/day in three divided doses (150 mg daily dose to be given as 300 mg in three divided doses on alternate days)
Pregabalin dosing in renal impairment (eGFR, mL/min/1.73 m2)
30–60	Initially 75 mg daily and maximum 300 mg daily
15–30	Initially 25–50 mg daily and maximum 150 mg daily in one to two divided doses
<15	Initially 25 mg once daily and maximum 75 mg once daily