Introduction
Obesity (body mass index (BMI) above 30 kg/m2) is
currently one of the major health issues, with a worldwide prevalence of
13% 1. Individuals with (morbid) obesity are exposed
to an increased risk of cardiovascular disease, cancer, diabetes
mellitus, hypertension, arthritis, sleep apnea, and other
co-morbidities, at higher mortality rates 2,3.
For patients with morbid obesity (BMI above 40 kg/m2)
or obesity with a BMI above 35 kg/m2 with one or more
comorbidities like type 2 diabetes or hypertension, modification of the
gastro intestinal (GI) tract by bariatric surgery is currently the most
effective long term treatment 4–7. Surgery results in
weight loss up to 32 ± 8% after two years and has shown to lead to
decreased incidence of diabetes, myocardial infarction, stroke, and
cancer, and in a reduction in overall long-term mortality4,8,9. In addition, obesity has a negative impact on
quality of life, which improves significantly after bariatric surgery10.
Common techniques used in bariatric surgery includes, the sleeve
gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB)11. The RYGB is associated with several anatomical and
physiological changes. RYGB introduces a small gastric pouch, which
results in an increased gastric pH 12,13. The gastric
pouch is connected to the lower part of the intestine, bypassing the
small intestine and biliary limb. During the SG procedure, a small
longitudinal stomach in created. For both types of surgery, these
alterations in the GI tract are known to lead to nutritional
deficiencies for which standardized nutritional supplementation is
commonly advised 7. Similarly, it can be anticipated
that these changes may alter the absorption of drugs given orally.
Many patients who undergo bariatric surgery use one or more drugs to
manage their co-morbid disease(s). Relevant drugs to these patients
include cardiovascular (26%) and antidiabetic drugs (26%), analgesics
(21%), anti-inflammatory and antirheumatic products (non-steroids)
(10%), antidepressants (21%), thyroid therapeutics (12%) and drugs
for obstructive airway disease (25%) 14.
In addition to the alterations in oral absorption due to modifications
in the digestive tract there are also changes in distribution,
metabolism and/or elimination of drugs as the result of substantial
weight-loss associated with bariatric surgery 15,16.
The purpose of this article is to provide an overview of how bariatric
surgery may influence the process of oral drug absorption and to give
specific dosage advice for commonly used potent drugs in this special
patient population.