Is phentermine (phentermine) safe for weight loss in a patient with cirrhosis (liver scarring) and Irritable Bowel Syndrome (IBS)?

From the Guidelines

Phentermine is not recommended for weight loss in patients with cirrhosis and IBS due to potential increased risk of serious side effects and worsening of IBS symptoms. This medication is a stimulant that works by suppressing appetite, but it can be particularly risky for individuals with liver disease, as cirrhosis impairs the liver's ability to metabolize medications properly, which could lead to increased blood levels of phentermine and potentially serious side effects 1. Additionally, phentermine can cause gastrointestinal side effects like constipation, diarrhea, and abdominal discomfort, which could worsen IBS symptoms.

For patients with cirrhosis and IBS seeking weight management options, it would be safer to pursue non-pharmacological approaches such as:

• Dietary modifications supervised by a dietitian
• Gentle physical activity as tolerated
• Behavioral therapy Any weight loss program for someone with cirrhosis should be gradual and medically supervised, as rapid weight loss can sometimes worsen liver function 1. If medication is deemed necessary, it should only be prescribed after careful evaluation by healthcare providers who specialize in liver disease and weight management. The American Gastroenterological Association (AGA) suggests using phentermine with lifestyle modifications for adults with obesity or overweight with weight-related complications, but this recommendation is conditional and based on low-quality evidence 1. However, in the context of cirrhosis and IBS, the potential risks associated with phentermine may outweigh its benefits, and alternative approaches should be prioritized.

From the FDA Drug Label

WARNINGS Phentermine hydrochloride tablets are indicated only as short-term monotherapy for the management of exogenous obesity. The safety and efficacy of combination therapy with phentermine and any other drug products for weight loss, including selective serotonin reuptake inhibitors (e.g., fluoxetine, sertraline, fluvoxamine, paroxetine), have not been established. Primary Pulmonary Hypertension (PPH) – a rare frequently fatal disease of the lungs – has been reported to occur in patients receiving a combination of phentermine with fenfluramine or dexfenfluramine The possibility of an association between PPH and the use of phentermine alone cannot be ruled out; there have been rare cases of PPH in patients who reportedly have taken phentermine alone. Valvular Heart Disease: Serious regurgitant cardiac valvular disease, primarily affecting the mitral, aortic and/or tricuspid valves, has been reported in otherwise healthy persons who had taken a combination of phentermine with fenfluramine or dexfenfluramine for weight loss The etiology of these valvulopathies has not been established and their course in individuals after the drugs are stopped is not known. The possibility of an association between valvular heart disease and the use of phentermine alone cannot be ruled out; there have been rare cases of valvular heart disease in patients who reportedly have taken phentermine alone

The FDA drug label does not answer the question.

From the Research

Safety of Phentermine for Weight Loss in Patients with Cirrhosis and IBS

• The safety of phentermine for weight loss in patients with cirrhosis and Irritable Bowel Syndrome (IBS) is a concern due to the potential for adverse interactions and complications 2.
• Phentermine-topiramate seems to have the highest weight loss potential, but special consideration should be given to neuropsychiatric disorders, cardiovascular comorbidities, and drug interactions in patients with cirrhosis and IBS 2.
• There is limited data on the use of phentermine in patients with cirrhosis and IBS, and more research is needed to fully understand its safety and efficacy in this population.

Efficacy of Phentermine for Weight Loss

• Phentermine has been shown to be effective for weight loss in various studies, with a significant decrease in body weight and improvement in metabolic parameters 3, 4, 5, 6.
• The efficacy of phentermine for weight loss is influenced by factors such as hunger and restraint, with individuals reporting greater hunger and less restraint being more likely to achieve significant weight loss 5.
• Phentermine-topiramate has been associated with the highest odds of achieving at least 5% weight loss at 52 weeks, compared to other weight loss medications 6.

Potential Adverse Effects

• Phentermine has been associated with adverse effects such as paresthesia, dysgeusia, dry mouth, constipation, and insomnia 3.
• The risk of adverse events, including cardiovascular events, should be carefully considered in patients with cirrhosis and IBS, and monitoring of liver function and other parameters may be necessary 2.
• The long-term efficacy and safety of phentermine for weight loss in patients with cirrhosis and IBS require further study.