Is it true that bariatric surgery affects the pharmacokinetic properties of drugs? This is an effective and safe operation that helps you lose weight and eliminate health issues. However, it is necessary to consider all the features and understand what you are dealing with. You have concomitant diseases, and you need to take medications. An important question: How does weight loss surgery affect medications? So, let’s describe bariatric surgery pharmacology considerations.
Obesity is associated with various dangerous diseases and leading causes of death, including stroke, heart disease, diabetes, and some types of cancer. Losing weight is very important for health. However, sometimes diets and exercise do not bring results. If diseases associated with obesity seriously affect health, then more serious and effective methods are needed. The patient resorts to bariatric surgery.
Many medications can be absorbed normally after this surgery. However, drugs such as slow-release medications require close monitoring in people who have had gastric bypass surgery.
In one type of this procedure, the upper part of the stomach is isolated from the rest. This creates a walnut-sized pouch. The new pouch can hold about 1 ounce of food, rather than the three pints of food the stomach can normally hold. The small intestine is cut and sewn directly to the remaining stomach pouch. This allows food to pass directly into the middle part of the small intestine.
However, many medications are absorbed normally in people who have had gastric bypass surgery, including most painkillers. However, in some special situations, drug absorption can be a problem.
Let’s analyze how weight loss surgery affects medications. So, bariatric surgical procedures lead to weight loss through two primary mechanisms: restriction and malabsorption. The surgery dramatically reduces the surface area of the gastrointestinal tract, affecting the absorption of nutrients and drugs due to the loss of mucosal exposure. Bypassing part of the small intestine may also alter drug metabolism, as it is one of the sites of first-pass metabolism in the body due to the large number of CYP3A4 enzymes.
The study noted that preclinical rodent models replicate human bariatric surgery. This may be very helpful in investigating the pharmacokinetics and pharmacodynamics of pharmacological interventions (Tichansky et al., 2008; Bueter et al., 2012).
Rodent studies focused on the pharmacokinetics of standard bariatric procedures. Fifteen studies were analyzed. They demonstrated the possible impact of bariatric surgery on drug distribution, metabolism, absorption, elimination, and potential mechanisms.
Since bariatric surgery has been shown to alter the physiology of the gastrointestinal tract directly, this affects nutrient absorption and may change the absorption of orally administered pharmacological agents (Sawaya et al., 2012). Unfortunately, there are no clear guidelines for dose adjustments after surgery.
Sixty studies examined the gastric bypass and medication effectiveness. Twenty-eight studies reported decreased drug absorption after bariatric surgery. Only four studies showed an increase in drug absorption. Unchanged drug absorption was observed in 23 studies after surgery.
Drug absorption after bariatric surgery is indeed variable. Unpredictability may result from factors related to the patient, drug, and/or type of surgery. After bariatric surgery, individual therapy with careful medication monitoring is needed. It is essential to visit a doctor and monitor your condition.
Bariatric procedures limit the oral bioavailability of drugs. After malabsorptive procedures, the expression of metabolic enzymes that reside in the upper small intestine is altered. This affects the bioavailability of some drugs. Most studies have shown faster absorption of various drugs after surgery due to decreased gastric volume and a more rapid rate of gastric emptying. A factor to consider is the decrease in liver size after bariatric surgery due to significant weight loss. This may decrease hepatic metabolism and increase the bioavailability of drugs, thereby affecting pharmacokinetics and pharmacodynamics.
Pharmacokinetic parameters clinicians consider postoperatively include gastric motility, volume, and pH; bile secretion; surface area; carrier proteins; and first-pass metabolism. Factors that must be monitored include plasma drug levels, laboratory markers, and patient clinical outcomes. Monitoring is essential for drugs with a narrow therapeutic index.
So, controlled-release drugs are broken down in the stomach and released into the body.
With controlled-release drugs, instead of taking several pills throughout the day, you only take one or two pills a day. These pills slowly release the drug over time. After gastric bypass, low acidity or changes in enzyme levels in the intestines can change how this drug is released, preventing the drug from reaching the bloodstream.
Care should also be taken by people taking antidepressants. After gastric bypass, patients may need to have their antidepressant dose changed or switch to a different type of antidepressant.
A doctor should closely monitor medications designed to regulate a person’s heartbeat and prevent irregular heartbeats in people who have had gastric bypass. The surgery may change the drug’s absorption. Drug dosages should be carefully followed to ensure that patients receive the correct amount of the drug.
The absorption of a drug depends on the special physicochemical properties of the drug: solubility, polarity, lipophilicity, and molecular size. Different effects are expected depending on the type of bariatric procedure. The rate or extent of absorption of an oral drug does not differ significantly in obese patients compared to lean individuals. Some examples of drugs studied in bariatric surgery include propranolol, midazolam, and cyclosporine A, which appear to have unchanged absorption after surgery.
On the other hand, another study examined the absorption of enoxaparin, a low molecular weight heparin (LMWH) administered subcutaneously to lean and obese volunteers. The rate of absorption of the drug was slower in obese individuals; however, the extent of absorption was complete in both groups. The increased rate of absorption after bariatric surgery may not always translate into significant clinical benefit; therefore, it is essential to consider the mechanism of action of the drug involved.
So, you want to lose weight and are interested in the behavioral features after bariatric surgery? Contact our experienced bariatric surgeon in Tuscaloosa for advice. We know how to carry out the procedure correctly, have a lot of experience, and have satisfied clients who were able to lose weight safely. We will answer all your questions. Contact us.
