Comparison of Oral Gabapentin and Pregabalin in Postoperative Pain Control After Photorefractive Keratectomy

Purpose: To compare the efficacy of oral gabapentin and its newer analogue pregabalin in postoperative pain control after photorefractive keratectomy (PRK).

Methods: One hundred and four patients who meet the inclusion criteria undergoing PRK in one or both eyes will be randomized into one of two treatment groups. Those in group A will be treated with gabapentin, and those in group B will be treated with pregabalin to control postoperative PRK pain. Patients in both groups will begin treatment two hours prior to surgery in order to achieve therapeutic blood levels of each medication. After surgery the patients will assess their pain level using the visual analogue scale (VAS) at different intervals of time - one hour after surgery, the evening of the surgery, and three times each day for three subsequent days. Patients will also daily assess their level of somnolence using the Epworth Sleepiness Scale (ESS) and record the presence of dizziness for the same amount of time. On the fourth day they will return to clinic for a postoperative appointment. At that time the pain, sleepiness, and dizziness assessment scales will be collected and analyzed. The patients will return one month later to further assess long-term pain and healing after PRK.

Results: Both gabapentin and pregabalin have been shown in previous studies to treat postoperative pain effectively. The effects of gabapentin 300 mg TID for 3 days versus pregabalin 50 mg TID for 3 days on decreasing overall postoperative pain following PRK will be presented.

Conclusion: The effectiveness of the two different treatment medications will be analyzed, and the conclusion will be based on the results.

METHODS:

One hundred and four patients who meet the inclusion criteria undergoing photorefractive keratectomy (PRK) in one or both eyes will be randomly assigned into one of two treatment groups via computer. Those in group A will be treated with gabapentin and those in group B will be treated with pregabalin to control postoperative PRK pain. Patients in both groups will begin treatment two hours prior to surgery. Patients in the gabapentin group will take 300 mg three times a day starting two hours prior to surgery and will continue for a total of four days. Patients in the pregabalin group will take 50 mg three times a day starting two hours prior to surgery and will also continue for four days.

Only the refractive surgery coordinator and the patient will know what medication the patient is taking. The patient will be instructed not to share this information with any other study participants or their surgeon. The coordinator will keep a list of the patients ID numbers and the treatments they are receiving.

Prior to surgery, each patient will be taught how to assess their pain level using the visual analogue scale (VAS), a well documented method of pain assessment. After surgery the patients will assess their pain levels at different intervals of time - one hour after surgery, the evening of the surgery, and three times a day for four subsequent days. Patients will also daily assess their level of somnolence using the Epworth Sleepiness Scale (ESS) and record the presence of dizziness daily for the same amount of time. On the fourth day they will return to clinic for a post operative appointment. At that time the pain assessment scales will be collected and analyzed. The patients will return at one month to further assess long term pain after PRK.

Statistical Analysis:

Postoperative pain levels recorded using the visual analogue scales, ESS, and self reported dizziness assessments will be collected on the fourth postoperative day. These will be compiled into data sets and analyzed. Data will be compiled into means with lower and upper quartiles and analyzed using a two-sided t test. The difference in pain levels will be described throughout the postoperative period to determine if one medication significantly reduces postoperative pain initially within the first 24 hours, during the interval between 24 hours to four days, and further after surgery (one month postoperatively). Data regarding levels of somnolence and dizziness will also be reported.

Eligibility Criteria:
Inclusion Criteria:

* 18 years of age or older
* Undergoing PRK in at least one eye

Exclusion Criteria:

* Serious medical problems within the last 6 months including myocardial infarction (heart attack), congestive heart failure, stroke, deep vein thrombosis, pulmonary embolism, and other conditions, etc.
* Serious kidney disease as evidenced by the need for dialysis or kidney transplant.
* History of seizure or other neurologic disorders.
* Patients intending to become pregnant or who are pregnant or nursing over the projected course of treatment.
* Currently taking gabapentin or pregabalin for other medical purposes.
* Known allergic reaction to gabapentin or pregabalin from previous use.
* Plans to move out of the area within 8 weeks after the surgery.