# Abstract

 

## Background Despite the fact that numerous medications have been introduced to treat renal colic, none has been proven to relieve the pain rapidly and thoroughly. In this study, we aimed at comparing the effects of intravenous lidocaine versus intravenous morphine in patients suffering from renal colic. 

## Methods In a prospective randomized double-blind clinical trial performed in the emergency department of Imam Reza educational hospital of Tabriz, Iran, we studied 240 patients, 18--65 years old, who were referred due to renal colic. Patients were divided into two groups. In group I (120 people) single-dose intravenous lidocaine (1.5 mg/kg) was administered and in group II (120 people) single-dose intravenous morphine (0.1 mg/kg) was administered slowly. Visual Analogue Pain Scale (VAS) was recorded while admission, 5, 10, 15 and 30 minutes after injection. Statistical data and results were studied using descriptive statistics as percentage and Mean ± SD. To compare the response to treatment, Mann--Whitney *U*-test was used in two groups. Consequently, the data were analyzed using the SPSS16 software. 

## Results Pain score measured in two groups five minutes after the injection of lidocaine and morphine were 65 % and 53 % respectively (95% CI 0.60 - 0.69, CI 0.48 -- 0.57, p = 0.0002).108 (90 %) patients (95 % CI 0.84 -- 0.95) from group I and 84 (70%) patients (95 % CI 0.62 - 0.78) from group II responded appropriately at the end of the complete treatment. The difference was statistically significant (p = 0.0001). 

## Conclusions Changing the smooth muscle tone and reducing the transmission of afferent sensory pathways, lidocaine causes a significant reduction in pain. 

## Trial registration Clinical Trials IRCT138901042496N3 # Results Eighty six patients of studied samples were male and thirty four were female in group I. In group II, ninety patients were male and thirty were female. There was no statistically significant difference between them regarding gender distribution (p = 0.559) (Table [1](#)). ::::table-wrap

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Demographics characteristics of both groups
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**Group I** **Group II** ***P*-value**

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Sex Male 71.7 % 28.3 % 0.559
Female 75 % 25 %
age 35.23 ± 12.37 37.71 ± 11.08 0.104\
Hydronephrosis left kidney 52 (43.3 %) 52 (43.3 %) 0.684
right kidney 57 (47.5 %) 53 (44.2 %)
did not have hydronephrosis 11 (9.2 %) 15 (12.5 %)
history of kidney stone and renal colic Recurrent Stone 49 (41.2 %) 64 (53.3 %) 0.06
First Stone 70 (58.8 %) 56 (46.7 %)
Stone side right kidney 60 (50 %) 57 (47.5 %) 0.698
left kidney 60 (50 %) 63 (52.5 %):::: Mean ages of the patients were 35.23 ± 12.37 years and 37.71 ± 11.08 years in group I and II respectively. The differences was not statistically significant (p = 0.104) (Table [1](#)). There was no statistically significant difference between mean patient pain scores before drug administration of two groups (p = 0.365). Pain relief in lidocaine group was statistically significant compared to the morphine group (p = 0.0001) (Table [2](#)). ::::table-wrap
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Comparison of the mean value of pain reduction between two groups
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**Group I** **Group II** ***P*-value**

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primary VAS 9.65 ± 0.88 9.74 ± 0.63 0.365
VAS^5^ 3.18 ± 2.27 4.45 ± 2.16 0.0001
VAS^10^ 1.83 ± 1.59 2.89 ± 2.07 0.0001
VAS^15^ 1.37 ± 1.32 2.55 ± 1.52 0.0001
VAS^30^ 1.13 ± 1.15 2.23 ± 1.57 0.0001:::: 108 patients (90 %) in group I responded to lidocaine successfully whereas in group II, 84 patients (70 %) responded properly to morphine, at the end of the study it was demonstrated that there were more considerable respond and pain relief in lidocaine group which was statistically significant (p = 0.0001). In the present study, patients were also evaluated regarding having history of kidney stone, renal colic as (with a history of referring to the hospital or recurrent stone, and first referral-first stone), side effects (all recorded side effects in both groups were mild and temporary), stone side and hydronephrosis (Tables [1](#),[3](#)). ::::table-wrap
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Percentage of patients reporting side effects
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Group I perioral numbness 3 (2.5 %)
transient dizziness 10 (8.3 %)
dysrathria 2 (1.7 %)
Without side effect 105 (87.5 %)
Group II hypotension 3 (2.5 %)
vertigo 2 (1.7 %)
nausea 9 (7.5 %)
vomiting 2 (1.6 %)
Without side effect 104 (86.7 %)
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Extracted trial result:
Outcome: Pain score after 5 minutes (continuous)
Intervention: Intravenous lidocaine
Comparator: Intravenous morphine
Intervention group size: 120
Intervention mean: 3.18
Intervention standard deviation: 2.27
Comparator group size: 120
Comparator mean: 4.45
Comparator standard deviation: 2.16