Orlistat
Orlistat is a reversible inhibitor of gastrointestinal lipases. Its label indicates it for obesity management alongside a reduced-calorie diet. Because it works by stopping fat being absorbed, it also interferes with things that are absorbed with fat, and the label’s most practical instructions follow from that.
Key points
- The label indicates it for obesity management including weight loss and weight maintenance, when used in conjunction with a reduced-calorie diet.
- It is also indicated to reduce the risk of weight regain after prior weight loss.
- Patients are advised to take a multivitamin containing fat-soluble vitamins to ensure adequate nutrition.
- That vitamin should be taken at least 2 hours before or after orlistat, such as at bedtime, and ciclosporin should be given 3 hours after orlistat.
How it works
The label describes orlistat as a reversible inhibitor of gastrointestinal lipases. Lipases break dietary fat down so it can be absorbed; inhibiting them leaves a portion of dietary fat unabsorbed and passing through instead.
Two consequences follow directly, and both are on the label. Fat-soluble vitamins travel with dietary fat, so absorption of those can fall too. And the effect depends entirely on there being fat in the meal, which is why it is prescribed alongside a reduced-calorie diet rather than as a substitute for one.
Safety specific to orlistat
Fat-soluble vitamins. The label advises patients to take a multivitamin containing fat-soluble vitamins to ensure adequate nutrition. This is a positive instruction rather than a caution, and it is easy to skip because it does not feel like part of the treatment.
Timing matters. The multivitamin should be taken at least 2 hours before or after orlistat, such as at bedtime. Taken at the same time it would be subject to the same blocked absorption, which defeats the point of taking it.
Ciclosporin. For patients receiving both orlistat and ciclosporin, the label directs that ciclosporin be administered 3 hours after orlistat. Ciclosporin is an immunosuppressant with a narrow margin, so this is a timing instruction to follow exactly rather than approximately.