Pregabalin

The probable mechanism of action is to reduce the release of several excitatory neurotransmitters by inhibiting calcium influx via the calcium channels ^{1) 2) 3) 4)}.

Pregabalin is pharmacologically superior to gabapentin due to its higher bioavailability (90% vs. 33%–66%), more rapid absorption (peak plasma level: 1 hr vs. 3–4 hrs) and linear increase in plasma concentration when its dose is increased. Lower doses of pregabalin than that of gabapentin (2–4 fold lower doses) have a similar analgesic effect on neuropathic pain, which makes pregabalin more advantageous in terms of the side effects from dosage ^{5) 6) 7)}.

Perioperative PG administration reduces early postsurgical pain at rest and particularly during movement after major spine surgery with less opioid consumption, and it seems to influence the improvement of overall QoL 3 months after surgery ⁸⁾.

Preoperative pregabalin administration is associated with less pain intensity and improved functional outcomes 3 months after lumbar discectomy followed by gabapentin and then placebo.Level of Evidence: 2 ⁹⁾.

Both pregabalin 300 mg day-1 and gabapentin 1,200 mg day-1 have more analgesic, anxiolytic and opioid-sparing effects, higher patient satisfaction and are more effective for preventing postoperative shivering than the placebo following lumbar laminectomy and discectomy. Findings revealed that pregabalin 300 mg day-1 had equivalent analgesic, adverse and opioid-sparing effects and patient satisfaction as gabapentin 1,200 mg day-1 ¹⁰⁾.

Combined administration of pregabalin and dexamethasone conferred analgesic benefits superior to those of pregabalin alone. This regimen also helped facilitate return to normal daily activity after surgery ¹¹⁾.

Dose

Perioperative administration of pregabalin 150 mg before and 12 hours after surgery, but not 75 mg, significantly reduced opioid consumption and the use of additional pain rescue for 48 hours after surgery without significant side effects in patients undergoing spinal fusion surgery ¹²⁾.

Evidence

There is high-quality evidence that Nonsteroidal antiinflammatory drugs reduces pain up to 24 hours postoperatively. The evidence for reductions in pain with dexmedetomidine, pregabalin or gabapentin, scalp blocks, and scalp infiltration is less certain and of very low to moderate quality. There is low-quality evidence that scalp blocks and dexmedetomidine may reduce additional analgesics requirements. There is low-quality evidence that gabapentin or pregabalin may decrease nausea and vomiting, with the caveat that the total number of events for this comparison was low ¹³⁾.

Case series

Of 105 patients who entered the run-in period, 47 patients (44.8%) were female and 58 (55.2%) were male. The Patients radicular pain mean score based on Numerical scale system (NRS) estimated before surgery was 7.22±1.95 in pregabalin14, 7.71±1.84 in pregabalin1 and 7.45±1.9 in control group. There were no statically significant differences between three groups (P-Value>0.05). The Patients back pain mean score based on NRS was 5.2±2.87 in pregabalin14, 5.11±3.23 in pregabalin1 and 6.4±3.06 in control group. This means that there were no significant differences in the overall score among those three groups (P-Value>0.05). In comparison to their preoperative pain, the average radicular pain in each group of patients improved significantly 4, 8, 12 and 24h after the operation (P-Value<0.001), but there were no significant differences in radicular pain improvements comparing three groups.

The results of this study indicate that 1day and 2 weeks post-operative 300mg pregabalin administration may not improve acute pain, morphine consumption and quality of life of patients after surgery. It seems that the diseases cause chronic pain that requires long-term treatment with higher doses ¹⁴⁾.