Pregabalin and gabapentin treatment in MS patients: Clinical experiences and therapeutic implications

Multiple Sclerosis (MS) is a chronic, progressive autoimmune disease of the CNS with a heterogenic clinical presentation. Patients suffer from a variety of symptoms leading to disability and a loss of life's quality. Besides a basic immunomodulatory therapy, many patients receive additional treatment which specifically addresses symptoms such as bladder dysfunction, daytime sleepiness, spasticity or sensory impairment. To treat paresthesia or paroxysmal pain, pregabalin (PGB) and gabapentin (GBP) are regularly prescribed. Both substances are structurally related to the neurotransmitter γ-aminobutyric acid (GABA) and seem to act as inhibitors of high-voltage-sensitive calcium channels (VSCC) that regulate the presynaptic calcium influx and accordingly neurotransmitter secretion. However, the exact mechanism of action remains elusive. To analyse the distribution, reasons for description and effects of both substances on the MS disease course itself, this retrospective study was performed. 505 patients were randomly included in our MS centre of the University of Wuerzburg (control group (c): 441, PGB treated: 33, GBP treated: 31) to observe retrospectively (4-year-period) changes in the expanded disability status scale (EDSS). There was no statistical difference between the groups concerning disease duration (c: 15 years, GBP: 15 years, PGB: 13 years), age (c: 45a, PGB: 50a, GBP: 47a) or gender (female patients: c: 71%, PGB: 70%, GBP: 81%). 34% of the patients were treated with GBP and 36% with PBG. Leading reasons for prescription were painful sensory impairment (37%), paresthesia (25%), paroxysmal pain (14%), trigeminal neuralgia (3%) and other causes (21%). In the subgroup of secondary progressive MS (SPMS) patients, treatment with PGB led to an interesting change of the EDSS median (c: 1.0, PGB: 0.5, GBP 1.3). In contrast, development of the EDSS in relapsing-remitting MS (RRMS) patients was comparable in all groups (c: 0, PGB: 1.0, GBP: not enough data points). In summary a putative disease modifying effect of PGB and GBP which goes beyond a mere symptom-related add-on therapy could be worth further investigation in larger, prospective studies and animal experiments.