Rationale: Post-operative nausea vomiting (PONV) is a common and distressing complication of anesthesia and the frequency increases with increase in the number of risk factors. Therefore, prophylaxis of PONV with at least two drugs is advised. Ondansetron with other antiemetic forms a good prophylactic combination for PONV however, the efficiency of Ondansetron with pyridoxine (commonly used drug for hyperemesis gravidarum) for PONV prophylaxis has not been established so far.

Aim: To compare pyridoxine-Ondansetron versus Ondansetron alone for post operative nausea vomiting prophylaxis in laparoscopic surgery.

Objective: To compare pyridoxine-Ondansetron versus Ondansetron alone for post operative nausea vomiting prophylaxis in laparoscopic surgery.

Primary objective: Incidence of PONV in first 24 hours after surgery.

1. Severity of PONV

2. Requirements of rescue antiemetic drugs.

3. Side effects , if any

Methods: 

This prospective, randomised double blind study will be conducted after obtaining Ethical committee approval and written informed consent from July 2025-December 2026 in the Department of Anesthesiology and Critical Care, UCMS and GTB Hospital, Delhi.

Inclusion criteria: Consenting ASAI/II, adult females >= 18 years old undergoing laparoscopy surgery requiring general anesthesia.

1. Pregnant patients 

2. Patients with cardiac, hepatic, renal disease and k/c/o tuberculosis.

3. Developmental delay, mental illness, severe neurological disease.

4. Allergic to any drug used in study.

5. Long term use of long acting antiemetics, emetogenic drugs, opoids, glucocorticoids or cancer chemotherapy and on any antiemetic in last 24 hours.

Tablet pyridoxine 200 mg will be given 60 minutes before induction of anesthesia with 1-2 sips of water in one of the 2 groups of patients. After evaluating the risk factors on Koivuranta score, monitors will be attached. General anesthesia will be induced with fentanyl (2mcg/kg)i.v. , propofol (2mg/kg) i.v and vecuronium (0.1mg/ kg) i.v.  Endotracheal intubation will be done and anesthesia will be maintained with isoflurane1-1.5% in air and oxygen. Ondansetron 4mg i.v. and paracetamol 1gm i.v.  will be given 30 minutes before the end of surgery. Neuromuscular block will be reversed with neostigmine (0.05mg/kg) i.v. and glycopyollate (0.01 mg /kg)i.v.  at the end of surgery and trachea will be extubated. If the patient develop nausea lasting >15 min or vomiting in the prospective period, Metoclopramide (rescue antiemetic) 10 mg i.v. will be given slowly. If PONV persist despite administering rescue antiemetic, the physician will be allowed to give additional antiemetics as per discretion.

Outcome measures: Incidence of PONV , time to first occurrence of PONV, severity, requirement of rescue antiemetic and side effects, if any, will be recorded until 24 hours post surgery.

Sample size calculation: as per previous study, PONV incidence was found was found to be 28% with Ondansetron alone and 6% when combination of Ondansetron- dexamethasone was given, i.e an absolute reduction by 22%. In the absence of incidence for Ondansetron- pyridoxine combination, to estimate an absolute risk reduction in the incidence of PONV by 22%, 41 patients in each group is required at alpha error of 5% and power of 80%, i.e. minimum of 82 patients. To account for 10% loss to follow up , 90 patients will be included with 45 in each group.

Statistical analysis will be done in SPS. Patient will be analysed based on intention to treat trial. Normality of data will be tested using kolmogrov-Smirnov test. Quantitative variables will be reported as mean+- SD or median [IQR]  depending upon their distribution as normal or non normal respectively, and qualitative variables will be reported as number(percentage). Unpaired t-test and Maan-Whitney U test will be used for analysis of qualitative variables. Repeated measures ANOVA will be used for analysis of repeatedly measured parameters. P<0.05 will be considered significant.