The release of novel agents for diabetes management has resulted in important advances for patients whose blood sugar is poorly controlled despite optimal treatment with previously available oral or injectable drugs. Careful patient selection is required for these newer medicines, however, in order to maximize therapeutic outcomes while minimizing the potential for adverse events. Pramlintide, exenatide, and inhaled insulin are recent additions to the list of diabetes drugs.

Pramlintide

Pramlintide (Symlin), an injectable amylin analog, is approved by the FDA for use in adults with type 1 or type 2 diabetes using insulin. It is designed to be given immediately before major meals (>30 g carbohydrates) in addition to an insulin bolus.^1-3

Patients must monitor blood glucose carefully when using pramlintide. Mealtime insulin doses are reduced by 50% at the start of therapy, then adjusted as needed.⁴ Doses of pramlintide are titrated based on whether or not the patient experiences persistent nausea. The product labeling highlights patients who are not candidates for treatment.⁴ These include patients who:

• Are poorly compliant with their current insulin regimen
• Have no awareness of hypoglycemia
• Are poorly compliant with glucose monitoring
• Have a hemoglobin A1C >9%
• Have a confirmed diagnosis of gastroparesis
• Require drug therapy for gastroparesis
• Have had episodes of hypoglycemia that required assistance in the past 6 months
• Are pediatric patients

Pramlintide prescribing information contains a black-box warning regarding the risk of hypoglycemia.

Exenatide

Exenatide (Byetta) is an injectable incretin mimetic that enhances insulin secretion, restores first-phase insulin response, and suppresses glucagon secretion. It reduces food intake and slows gastric emptying. Exenatide is dosed twice daily and is titrated upwards over 1 month from a 5-mcg to a 10-mcg dose based on the patient's experience with nausea. Patients should be advised that treatment with exenatide may result in a reduction in appetite, food intake, and/or body weight, and that there is no need to modify the dosing regimen because of these effects.⁵ A prefilled injection pen simplifies administration.

Exenatide should not be used in patients with type 1 diabetes or for the treatment of diabetic ketoacidosis. It is not a substitute for insulin. Use of exenatide is not recommended in patients with end-stage renal disease or severe renal impairment, or in patients with severe gastrointestinal (GI) disease. It should be used with caution in patients receiving oral medications that require rapid GI absorption.⁵

Inhaled Insulin

The third new agent, insulin human [rDNA origin] inhalation powder (Exubera), has recently been approved by the FDA. The drug is the first inhaled, noninjectable insulin option available in the United States. Clinical trials showed that inhaled insulin was as effective as short-acting injectable insulin for achieving glycemic control in adults with type 1 and type 2 diabetes. Addition of inhaled insulin to oral medications in type 2 diabetes also resulted in better glucose control in patients who were poorly controlled on oral agents alone.^6-8

The benefits of inhaled insulin from a patient acceptance standpoint are clear. Inhaled insulin may replace short-acting insulin in some patients, or provide better glucose control in patients who are afraid of injections. Inhaled insulin requires a special device, however, that is much larger than standard inhalers. The process of administering the dose requires several steps, which require a certain degree of dexterity. The inhaler must be cleaned regularly.

Use of the inhaled product is not recommended in patients who have chronic lung diseases.⁹ It is contraindicated in patients with poorly controlled or unstable lung disease, because variations in lung function can affect absorption and increase the risk for hypoglycemia or hyperglycemia. Blood glucose should be monitored closely during respiratory illnesses that occur while inhaled insulin is being used. Because of concerns about the long-term effect of inhaled insulin on lung function, the manufacturer recommends a lung function test at the beginning of treatment, at 6 months of therapy, and then yearly if lung function is stable. Inhaled insulin is contraindicated for patients who smoke or who have stopped smoking in the past 6 months because of an increased risk of hypoglycemia.

Dr. Garrett is a clinical pharmacist practitioner at Cornerstone Health Care in High Point, NC.

For a list of references, send a stamped, self-addressed envelope to: References Department, Attn. A. Rybovic, Pharmacy Times, Ascend Media Healthcare, 103 College Road East, Princeton, NJ 08540; or send an e-mail request to: arybovic@ascendmedia.com.