Evaluation of preoperative administration of the oral melatonin on postoperative pain in lumbar spinal surgeries

Based on recent studies suggesting the effectiveness of melatonin on postoperative pain and the urgent need for a treatment to reduce pain in patients after surgery. On the other hand due to the lack of similar studies in our country, we aim to conduct this study.

A concealed, randomized, blinded, third phase controlled clinical trial with a parallel group design of 46 patients, enrolled between April and May 2022.

Patients who undergo elective spinal surgery in Imam Khomeini Hospital in Tehran are included in the study and one hour before the operation, the first group is given 5 mg of oral melatonin and the second group is given a placebo. After surgery at 1, 2, 6, 12 and 24 hours after surgery, patients' pain intensity was measured using VAS Patients were randomly assigned to treatment groups. None of the patients, researchers, or physicians evaluating the outcome were aware of the type of treatment.

Patients who undergo elective lumbar spinal surgery are included in the study. Exclusion criteria include non-elective surgery, coagulative disorders, kidney or liver failure, opioid abuse, use of any other analgesics, taking medications interfere with melatonin, history of drug allergy to melatonin.

Patients are divided into two groups. One hour before surgery, the first group receives 5 mg of oral melatonin and the second group receives placebo.

Severity of post operative pain based on Visual Analogue Scale(VAS)

In this study, we use block randomization method, a subtype of the restricted randomization. Blocking is usually used for balance in the number of samples assigned to each study group. This feature helps researchers to have equal numbers of samples assigned to each of the case groups when the intermediate analyzes are required during the sampling process. The size of all the blocks is equal and in this RCT we used two-group trial of 6 blocks (including 3 participants in the intervention group and 3 participants in the placebo group). Random allocation software are used as randomization tools. Random sequence generation software in addition to simple randomization capable generates random sequences by block generation method. For hiding, we used allocation concealment. A method for random sequencing of the study participants in a way that before the individual is assigned, the assigned group is not specified. By using sequentially numbered, sealed, opaque envelopes in which the created random sequences are registered on a card. The cards are placed in the envelopes in order. To maintain a random sequence, also on the outer surface of the envelope. The numbering is done in the same way. Finally the envelope are pasted and placed in a box, respectively. At time to start registration of participants, based on the order of entry of the eligible applicants. One of the envelopes is opened in order and the assigned group of the participant will be revealed

In this study, participants (patients) as well as the researcher and outcome assessor(one person has the both latter roles) are blind. The patient is unaware that he is taking the drug or placebo exactly. The lead researcher, who also evaluats the outcome of the study, similarly do not know which patient receives either the medication or the placebo.