Effect of Orlistat on Prothrombin Time (PT) and Partial Thromboplastin Time (PTT) in Wistar Rats

Context: Orlistat is one of the few anti-obesity drugs that have been approved by FDA. It reduces the lipid absorption by 30% in its therapeutic dose by means of reversible inhibition of gastrointestinal lipases. Objective: Since vitamin K (a lipid soluble vitamin) is important in the synthesis of factors 2, 7, 9 and 10 of the coagulation cascade, we hypothesized that reduction in lipid absorption can cause vitamin K malabsorption and thus coagulation dysfunction. Subject: 18 Wistar rats divided in three groups. For the purpose of testing our hypothesis, we decided to give Orlistat to Wistar rats (in the form of solution in alcohol), for one week, one month and three months. Thus we made three groups including Control 1 group which only used water, Control 2 group which used water and alcohol and control 3 groups which used water, alcohol and Orlistat as its drink. After measuring PT and PTT of each rat, we used one way analysis of variants for the analysis of the results. Results: PT and PTT didn’t follow a predictable pattern through each series of experiments and therefore comparison wasn’t possible between different series of experiments. However, in every three series, both PT and PTT increased as a result of Orlistat consumption and the significancy of difference between control 2 and case group increased as the time of experiments got longer. This mentioned significancy was 0.905, 0.820 and 0.495 for PT, and 0.888, 0.734 and 0.538 for PTT during one week, one month and three months experiment, respectively. Conclusion: Our results showed that Orlistat didn’t have a significant effect on neither PT nor on PTT in the duration of our research (<3 months). However, it can be predicted that longer times of Orlistat consumption may lead to significant effects on PT and PTT.