Side Effects of Chlorpropamide (Diabense)
Chlorpropamide, referred to by the brand name diabenese, is a drug in the sulfonylurea class. This class is normally used in the treatment of Type 2 diabetes. It is a long-acting 1st generation sulfonylurea. It has more side effects than other sulfonylureas and its use is no longer recommended.
Mechanism of Action
Diabenese exhibits its clinical effects in the same way as other sulfonylureas. It acts to increase the secretion of insulin. This counters the limited release of insulin in diabetes. It has a relatively long half-life (how long it takes for plasma to be removed from a drug), and as such sulfonylureas with shorter half-life that are less likely to cause hypoglycaemia (low blood sugar) and preferred for treatment (Diabenese label reported by the FDA).
Common Side Effects
A number of common side effects are associated with diabenese, according to the FDA. These occur in more than 1% of patients):
Rare side effects are cholestatic jaundice (yellowing of the skin), hepatitis (inflammation of the liver), pruritis (itching), allergic skin reactions like erythema (redness), hypoglycaemia (low blood glucose concentration), photosensitivity, leukopenia (low white blood cell count), agranulocytosis (deficiency in granulocytes), haemolytic anemia (low red blood cell count), dizziness, and headache.
About Pharmacogenetic Testing
Diabenese is usually a well-controlled medication and many patients do not suffer adverse side effects. However there are exceptions. This inter-patient variability has a number of different explanations. One significant factor is the differences in the patient’s genetics. Individuals with polymorphisms in the genes that code for the receptors and enzymes that interact with Diabenese can alter an individual’s reaction to the medication.
For example, patients with glucose 6 phosphate dehydrogenase (G6PD) have a higher probability of suffering from hemolytic anemia. Caution should be used when prescribing the drug to those patients. Diabenese is metabolized by the cytochrome P450 superfamily of enzymes, namely isoenzymes CYP2C9 and CYP2C19. Polymorphisms in these enzymes can result in poor metabolism and increased blood concentration of Diabenese. This might result in increased probability of developing side effects when taking the drug.
Know Your Genetic Risk with the Rxight® Genetic Test
Identifying these polymorphisms, can therefore, aid in clinical decision-making. A doctor may alter the dose of Diabenese or may not prescribe the medication at all. However, pharmacogenetics testing is new and not standard practice in many hospitals. MD labs provides a genetic testing service, Rxight, which sequences 18 genes (including cytochrome P450 enzymes like CYP2C9 and CYP2C219) to establish how a patient is likely to respond to Diabenese amongst hundreds of clinically relevant medications. If the drug is not suitable for the patient, an alternative is offered.
Contributors to this Article:
Michael Sapko, MD, PhD; and Deborah Kallick, PhD, Medicinal Chemistry
Read more about Rxight® Genetic Health Testing