Comparison of Ketamine and Morphine for Pain Control in Patients With Renal Colic: A Randomized Clinical Trial

This study aims to compare the efficacy and safety of low-dose ketamine versus morphine, both administered in combination with ketorolac, for pain management in patients presenting to the emergency department with renal colic. Pain reduction, time to adequate pain relief, need for rescue analgesia, and adverse events will be evaluated and compared between the two treatment groups.

A randomized, double-blind, parallel-group trial involving 340 patients. Block randomization (size 4, ratio 1:1) will be computer-generated, with allocation concealed using sequentially numbered, opaque, sealed envelopes.

The trial will be conducted at Firoozabadi Hospital ED. Patients will be randomized to ketamine or morphine, both with ketorolac. Drugs will be prepared in identical syringes. Patients, treating physicians, outcome assessors, and statisticians will be blinded. Pain scores at 0, 15, 30, 45, and 60 minutes, adverse events, and rescue analgesia will be recorded.

A total of 340 patients aged 18–65 years presenting to the emergency department with renal colic and a pain score greater than 4 on the Visual Analog Scale (VAS) will be enrolled after providing informed consent. Patients who are pregnant, require immediate surgical intervention, or have a history of asthma or schizophrenia will be excluded.

Patients will be randomly assigned to two groups. The intervention group will receive intravenous ketorolac 30 mg plus intravenous ketamine 0.3 mg/kg. The control group will receive intravenous ketorolac 30 mg plus intravenous morphine 0.1 mg/kg. Rescue analgesia will be provided when indicated according to the study protocol.

Change in VAS pain scores at 15, 30, 45, and 60 minutes; time to adequate pain relief (VAS less than 4).

Individual randomization will be performed using block randomization with a fixed block size of four and a 1:1 allocation ratio. The random allocation sequence will be generated by an independent statistician using Random Allocation Software. After obtaining informed consent, eligible patients will be randomly assigned to either the intervention or control group. Allocation concealment will be ensured using sequentially numbered, opaque, sealed envelopes (SNOSE). The envelopes will be prepared according to the random allocation sequence and opened sequentially after enrollment of each eligible participant.

In this study, participants, treating physicians, outcome assessors, and the data analyst will be blinded to treatment allocation. Study medications will be prepared by a nurse who will not be involved in outcome assessment or data collection. Both medications will be prepared in identical 10-mL syringes, without labels identifying the allocated treatment, and adjusted to the same final volume to maintain a similar appearance. Pain intensity and other study outcomes will be assessed and recorded by a trained researcher who will remain unaware of treatment allocation. Data will be provided to the statistician using coded group identifiers, without revealing the actual treatments. Allocation codes will remain confidential until completion of the study and final analysis and will be disclosed only when medically necessary, such as in the event of a serious adverse reaction. Due to differences in the adverse-effect profiles of the study medications, inadvertent unblinding may occur.