Drugs oral hypoglycemic agents

Itraconazole has significant interactions with a number of commonly prescribed drugs, such as rifampin, phenytoin, and carbamazepine. Itraconazole raises serum digoxin and cyclosporine levels and may affect the metabolism of oral hypoglycemic agents and coumadin. Absorption of itraconazole is impaired by antacids, Hj blockers, proton pump inhibitors, and drugs that contain buffers, such as the antiretroviral agent didanosine. 

Drug interactions Sandostatin has been associated with changes in nutrient absorption, so it may effect the absorption of orally administered drugs. Concomitant administration of Sandostatin with cyclosporine may decrease blood levels of cyclosporine and result in transplant rejection. Patients receiving insulin, oral hypoglycemic agents, beta blockers. 

Pharmacodynamic interactions are also of great clinical significance. The additive CNS depression that occurs when alcohol is combined with other CNS depressants, particularly sedative-hypnotics, is most important. Alcohol also potentiates the pharmacologic effects of many nonsedative drugs, including vasodilators and oral hypoglycemic agents. 

In 70 non-insulin-dependent patients with diabetes, taking one of five different oral hypoglycemic drugs, 21% of prescriptions were associated with a low plasma sodium concentration, but it was lower than 129 mmol/1 in only 8% (75). Every oral hypoglycemic agent was associated with a low plasma sodium concentration, which normalized on withdrawal. Extreme hyponatremia was only seen with chlorpropamide and, in one case, with glibenclamide. 

The drug with the higher affinity constant will successfully displace the drug with the lower. The result is an increase in the free drug concentration of the latter. For example, tolbutamide (an oral hypoglycemic agent used in maturity-onset diabetes mellitus) is approximately 95 percent bound and 5 percent free (see Table 4.1). In the presence of the anti-inflammatory drug phenylbutazone (which is nearly 100 percent... 

Therapeutic use in hypertension The cardioselective p-blockers are useful in hypertensive patients with impaired pulmonary function. Since these drugs have less effect on peripheral vascular p2 receptors, coldness of extremities, a common side effect of p-blocker therapy, is less frequent. Cardioselective p-blockers are useful in diabetic hypertensive patients who are receiving insulin or oral hypoglycemic agents. 

These agents are useful in the treatment of patients who have non-insulin-dependent diabetes, but cannot be managed by diet alone. Oral hypoglycemic agents should not be given to patient s with Type 1 diabetes. Figure 26.11 summarizes the oral antidiabetic drugs. 

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