Sitagliptin is licensed for adjunctive use with metformin or a glitazone in patients with type 2 diabetes to improve glycaemic control. It is available as a 100mg tablet with dosing as a single daily administration. It is the first in a new class of agents called dipeptidyl peptidase 4 (DPP-4) inhibitors which enhance the levels of the incretin hormones naturally secreted after eating food. These hormones act physiologically to increase insulin secretion and decrease glucagon secretion.
As this is a new drug data are limited, however based on research experience:
- It is not recommended for use in anyone under 18 years old due to insufficient safety and efficacy data
- Care should be used in patients aged over 75 years old as only limited data are available. No dose adjustment is expected to be necessary
- No dose adjustment is required in mild renal insufficiency (creatinine clearance greater than 50ml/min). Sitagliptin should not be used in patients with moderate to severe renal insufficiency
- No dose adjustment is required for mild to moderate hepatic insufficiency. No data are available in severe hepatic insufficiency, use is not recommended
- No data are available in pregnancy or breast feeding, use is not recommended
In clinical studies in 2,700 patients of up to 2 years in duration the most commonly observed side effects included nausea, upper abdominal pain, diarrhoea, somnolence, anorexia, weight loss and hypoglycaemia.
As with all new drugs, initial use should be cautious. This drug is a useful addition to the currently available hypoglycaemics. It may be useful in patients already on metformin who are contraindicated to or suffer intolerable side effects from sulphonylureas or glitazones.
Action: Clinicians should be aware of this new class of drugs. An initially cautious approach to use would place them as last line agents when contraindications or side effects are limiting use of existing therapies.