Is orlistat likely to affect the blood, eg blood coagulation or blood cells?/nThe questioner works

Fråga: Is orlistat likely to affect the blood, eg blood coagulation or blood cells?

The questioner works at a blood donation centre and would like to know whether treatment with orlistat could have any adverse effects on the blood with respect to the donors and the recipient?

Sammanfattning: There is no data indicating that orlistat could cause adverse effects on the blood or on the blood cells. There are some studies indicating that long-term treatment with orlistat may reduce the absorption of fat-soluble vitamins such as vitamin A, D, E and K, that are involved in the blood coagulation. Therefore the manufacturer recommends a diet containing a rich amount of fruit and vegetables, and a multivitamin supplement could also be considered.

Svar: Orlistat (Xenical) is a newly registered drug used for treatment of obesity. It is recommended for people with a Body Mass Index (BMI) equal to or higher than 30 kg/m2, or for overweight patients (BMI > 28) with co-risk factors such as high blood pressure (1). Orlistat specifically inhibits lipases and it acts in the gastrointestinal lumen where it prevents the lipase-catalysed breakdown and thereby reduces the dietary ingested fat by about one third (2). Normal dose is 120 mgx3. The absorption of orlistat is negligible. The plasmaconcentration after therapeutic doses are < 10 ng/ml but the whole blood concentration is not kown. Some metabolism of the drug is likely to take place in the gastrointestinal walls, about 97 per cent of the administered dose is excreted in faeces and 83 per cent of this as intact orlistat (3).

A search in Medline has not revealed any documentation indicating that orlistat could affect the blood or the blood cells. Neither did the manufacturer, (Roche), have any information concerning this type of adverse effect, and it is considered unlikely by a representative of the company (4).

Long-term treatment (up to two years) of orlistat could theoretically reduce the absorption of fat-soluble vitamins, A, D, E, K and beta-carotene (1). One multicentre, randomised, double-blind parallel study including 676 patients, male and female, showed that the mean levels of vitamin A, D, E and beta-carotene remained within the clinical reference ranges and that supplementation rarely was required (5). However, there was no information concerning the effects on vitamin K levels in this study.

The manufacturer recommends that patients treated with orlistat should keep a diet that contains a high amount of fruit and vegetables in order to assure an optimal nutrient supply. A multivitamin supplement can be considered (1). 1 Produktresume orlistat (Xenical) 1999

2 McNeely W, Benfield P: Orlistat. Drugs 1998; 56: 241-249
3 FASS 1998 (The Swedish catalogue of approved medical products)
4 Expert consultation Claes Helmers, MD, Roche

5 van Gaal LF, Broom JI, Enzi G, Toplak H, The Orlistat Dose-Ranging Study Group: Efficacy and tolerability of orlistat in the treatment of obesity: a 6-month dose-ranging study. Eur J Clin Pharmacol 1998; 54: 125-132