title: Effects of varying doses of tramadol on gastric pH.
abstract: BACKGROUND
  Tramadol is licensed primarily as an analgesic, but has additional properties, one of which is the ability to increase gastric pH. However, it has not been established if this action is dose related, hence we set out to provide further evidence about this action of tramadol.
  
  
  METHODS
  Fifty-five female adult patients presenting for gynecological surgery were randomized into three groups. After induction, 2.5 ml of gastric juice was aspirated to determine baseline pH, after which groups 1, 2, and 3 received 50 mg, 75 mg, and 100 mg of IV tramadol, respectively. Gastric pH was subsequently assessed every 30 min for as long as the surgery lasted.
  
  
  RESULTS
  There was no significant difference in the pH of the three groups before anesthesia (3.88 ± 0.75, 3.54 ± 0.73, and 3.75 ± 0.70; P = 0.393). Similarly, no significant statistical difference was observed in the pH of the three tramadol groups during the subsequent three readings (pH1: 4.21 ± 0.93, 4.27 ± 0.95, 4.07 ± 0.82; pH2: 4.75 ± 1.00, 4.68 ± 0.94, 4.59 ± 0.78; pH3: 5.33 ± 0.86, 5.13 ± 0.95, 4.97 ± 0.78; P = 0.793, 0.876, and 0.490). There were statistically significant increases in the pH of each group when the baseline pH was compared with the subsequent three readings, with P values of 0.002, 0.0001, 0.001 in the 50 mg group, 0.0001, 0.0001, 0.0001 in the 75 mg group, and 0.008, 0.0001, 0.001 in the 100 mg group.
  
  
  CONCLUSIONS
  Our result further confirms that tramadol elevates gastric pH. However, the degree of elevation was not found to be dose dependent.
authors.affiliation: Department of Anaesthesia, College of Medicine, University of Ibadan, Ibadan, Nigeria.
authors.forename: Babatunde B
authors.initials: BB
authors.lastname: Osinaike
authors.affiliation: Department of Chemical Pathology, College of Health Sciences, Ladoke Akintola University of Technology, Osogbo, Nigeria.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Ogunro
authors.affiliation: Department of Anaesthesia, College of Health Sciences, Ladoke Akintola University of Technology, Osogbo, Nigeria.
authors.forename: Emmanuel O
authors.initials: EO
authors.lastname: Oyebamiji
authors.affiliation: Department of Pharmacology, College of Health Sciences, Ladoke Akintola University of Technology, Osogbo, Nigeria.
authors.forename: Titus O
authors.initials: TO
authors.lastname: Ogungbamigbe
keywords: Dose; gastric pH; tramadol