Gabapentin Superadded to a Pre-Existent Regime Containing Amytriptyline for Chronic Sciatica.

Setting: There is currently a gross lack of evidence base guiding the medical management of chronic sciatica (CS). Only scant previous studies have assessed gabapentin (GBP) in CS. Extrapolating NICE-UK guidelines, prescribing authorities often insist on trialling anti-depressants (e.g., amytriptyline, AMP) as a first line for neuropathic pain states such as CS. When super-adding second-line agents, such as GBP, NICE-UK encourages overlap with first-line agents to avoid decreased pain-control. No study has reflected this practice.

Objective: Evaluate efficacy and side effects (SE) of GBP superadded to a pre-existent regime containing AMP for CS.

Subjects And Methods: Prospective cohort of patients with unilateral CS attending a specialist spine clinic. Eligible patients had experienced partial benefit to a pre-existent regime containing AMP: none had significant SE. No drugs other than GBP were added or discontinued (the latter was considered inequitable) for 3 months. Visual analog pain score (VAS), Oswestry disability index (ODI), and SE were recorded.

Results: Efficacy: in 56% (43/77) there were reductions in VAS (5.3 ± 3.6→2.8 ± 2.7, P < 0.0001) and ODI (42.8 ± 31.1→30.7 ± 25.2, P = 0.008). SE: Eighty-two SE (23 types) were reported in 53% (41/77). Efficacy was less in those with SE: a trend existed for a lesser reduction in VAS (2.0 ± 2.4 v 3.0 ± 2.7, P = 0.08), which proved significant for ODI (8.1 ± 11.4 v 16.7 ± 18.2, P = 0.01). Thirty-four percent (26/77) discontinued GBP all within 1 week (i.e., during titration).

Conclusion: This is the first prospective cohort study of GBP super-added to a pre-existent regime containing AMP for CS, as per routine clinical practice and NICE-UK principles. Super-added GBP demonstrated further efficacy over the previous regime in 56%; however, SE were frequent (53%) and diverse (23 types), and 34% abruptly discarded GBP. Although SE were associated with decreased efficacy, 37% nevertheless tolerated GBP despite SE.