Evaluating the preemptive effect of metoclopramide and aminophylline on pain after deep vitrectomy

Comparison of aminophylline with metoclopramide on reducing pain intensity after deep vitrectomy

This study is a randomized clinical trial with the control group, with parallel groups, double-blinded, phase 3 conducted on 105 patients randomized with random allocation software.

Participants selected randomly using random allocation software will be divided into groups receiving metoclopramide, aminophylline, or placebo. After surgery, each group receives medication or a placebo, and then vital signs and postoperative pain will be checked at different times. Participants and clinicians will be blind to study groups.

Inclusion criteria: Patients undergoing pars plana deep vitrectomy (20G) surgery, Age between 18 to 75 years, Status classification I or II according to the American Society of Anesthesiologists (ASA) Status Classification System, body mass index (BMI) less than 35, ability to speak, written informed consent Exclusion criteria: History of taking corticosteroids and immunosuppressants since one month before surgery, history of allergies to metoclopramide or aminophylline, taking metoclopramide, aminophylline, or any other analgesics 24 or less than 24 hours before surgery, history of malignancy, uncontrolled diabetes, smoking cigarettes, addictive drugs, and alcohol abuse, chronic pain for more than six months, mental illness, evident preoperative anxiety or tachycardia, history of taking anti-anxiety or anti-arrhythmic medications, history of general anesthesia, by using volatile anesthetics, in the last six months

Patients in the first group will receive 0.1 mg/kg of metoclopramide, and the second group will receive 4 mg/kg intravenous aminophylline. The placebo group will receive 10 ml of normal saline solution.

The intensity of pain based on the VAS scale

In this study, patients are listed according to referral to surgical centers, arranged from one to 105, respectively. These numbers are then randomly divided into three groups (each will contain 35 cases) by Random Allocation Software (available at: http://ftp.mui.ac.ir/RA.zip). The software is set to generate numbers in a single block, based on numeric and sequential coding with a length of three digits. By hitting the Generate key, numbers from one to 105 are randomly assigned to each of the three groups defined in this study (metoclopramide, aminophylline, and placebo). The output list is copied from the software and will be copied in Microsoft Excel software.

An anesthesiologist who will be unaware of the study methods would prepare the drugs in similar syringes and label them with random numbers to be delivered to the study conductor. Patients will be also unaware of the type of medication they receive.