The Food and Drug Administration (FDA) has approved a combination of sitagliptin (Januvia) and simvastatin (Zocor) that treats both type 2 diabetes and hyperlipidemia; the combination drug Juvisync is designed to help promote drug adherence by simplifying treatment regimens. Type 2 diabetes and hyperlipidemia, both of which increase the risk of cardiovascular disease, are often seen together.
Sitagliptin is an antihyperglycemic drug that works by inhibiting dipeptidyl peptidase-4 (DPP-4) and promoting the action of endogenous incretin hormones, which are released to maintain normal levels of glucose in response to glucose elevations that occur after a meal. Incretin hormones increase insulin synthesis and the release of insulin from pancreatic β cells through intracellular signaling pathways. They're metabolized rapidly by DPP-4. With sitagliptin use, incretin hormone activity is more pronounced, and insulin release continues as glucagon levels decrease.
Simvastatin lowers low-density lipoprotein (LDL) cholesterol and competitively inhibits HMG-CoA reductase, the enzyme that catalyzes the early rate-limiting step in cholesterol biosynthesis. The effect is to increase high-density lipoprotein cholesterol and to decrease LDL cholesterol, total cholesterol, very–low-density lipoprotein (VLDL) cholesterol, and plasma triglycerides. The mechanism that lowers LDL cholesterol may involve both a reduction in VLDL cholesterol concentrations and increased catabolism of LDL cholesterol.
Evidence exists that statins work in other ways as well to decrease the risk of cardiovascular events. They appear to exert a positive effect on the vascular endothelium by increasing the bioavailability of nitric oxide (which promotes vasodilation), promoting reendothelialization, reducing oxidative stress, and inhibiting the inflammatory response. Statins also stabilize atherosclerotic plaque in blood vessels; ruptured plaque is a central component of acute coronary syndrome. They also decrease thrombotic action in the blood. (For more on the mechanics of these two drugs, see Aschenbrenner DS, Venable SJ. Drug therapy in nursing. 4th ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams and Wilkins; 2012.)
Various strength combinations will be created using the most commonly prescribed doses of each drug. The first combinations released will be 100 mg/10 mg, 100 mg/20 mg, and 100 mg/40 mg of sitagliptin and simvastatin, respectively. The drug's manufacturer plans to release combinations in the future with sitagliptin doses of 50 mg instead of 100 mg. The FDA is requiring a postmarketing clinical trial to compare the glucose lowering ability of sitagliptin alone with that of sitagliptin in combination with simvastatin because of a potential increase in glucose levels caused by statins.
Because sitagliptin increases the risk of severe pancreatitis, a medication guide carrying that warning will be included with each prescription of Juvisync. Juvisync carries the same risks of drug interactions and adverse effects that each drug carries individually.
Nurses caring for patients prescribed Juvisync should instruct them to read the medication guide each time a prescription is refilled to obtain the most up-to-date safety information. Nurses should provide all teaching relevant to sitagliptin and simvastatin. Patients who require sitagliptin or simvastatin in doses other than those in the fixed-dose combinations should receive each drug as an individual entity. To read the Juvisync medication guide, go to http://1.usa.gov/uI3Aqm.