Clinicians can do 3 easy things when caring for diabetic patients to prevent drug interactions: implement medication reconciliation into daily practice, understand how drugs interact with each other, and know high-risk antidiabetic drugÂâ€“drug combinations.
Diabetic patients represent 9.3% of the US population.1Most adults with diabetes have at least one comorbidity, such as depression, arthritis, heart disease, high low density-lipoprotein cholesterol, or high blood pressure.2Patients may take an average of 4 to 5 medications daily for their diabetes and comorbidities, excluding OTC medications, vitamins, and minerals.3Each additional medication increases the risk of potential problems, including drug—drug interactions.
Clinicians can do 3 easy things when caring for diabetic patients to prevent drug interactions: (1) implement medication reconciliation into daily practice, (2) understand how drugs interact with each other, and (3) know high-risk antidiabetic drug­—drug combinations.
A small yet important part of any patient encounter is a complete medication reconciliation, the process of identifying the most accurate list of all medications a patient takes.4Having a comprehensive list allows clinicians to provide quality care, make accurate recommendations, and avoid drug—drug interactions.
Building medication reconciliation into your practice using the following simplified process is a great way to prevent errors and potential adverse events4,5:
Drugs can interact with each other pharmacodynamically or pharmacokinetically. Pharmacodynamic interactions involve what the body does to the drug, including absorption, distribution, metabolism, and excretion (the ADME principle). Pharmacokinetic interactions involve how the drug affects the body. Either type of interaction can lead to a drug’s being less effective, having unexpected and potentially dangerous adverse effects, or having increased drug action.6
The liver is critical for many drugs’ metabolism and excretion. Hepatocytes contain many enzymes that metabolize different chemicals. Cytochrome P450 (CYP450) enzymes are the most important, as many medications are CYP450 substrates.
Think about drug interactions in 4 ways7:
Relevant drug­—drug combinations and the mechanism of interaction are summarized in theTable.7-9Many clinically relevant drug interactions are based on the drug’s effect on specific CYP50 enzymes. Thiazolidinediones, sulfonylureas, and meglitinides are the most susceptible to these types of interactions in the following ways:8
With the exception of saxagliptin, dipeptidyl-peptidase-4 (DPP-4) inhibitors also show a very low interaction potential. Specifically, saxagliptin is affected by CYP3A4 inhibitors and inducers. On the other hand, giving DPP-4 inhibitors with drugs that affect the drug transporter P-glycoprotein might affect plasma levels.
P-glycoprotein has a wide substrate spectrum. It is involved in the transport of drugs from different drug classes including antineoplastic drugs (eg, docetaxel, etoposide, vincristine), calcium channel blockers, calcineurin inhibitors (eg, cyclosporine, tacrolimus), digoxin, macrolide antibiotics (eg, clarithromycin), and protease inhibitors.8
A newer antidiabetic drug class, sodium-glucose cotransporter-2 inhibitors, has a very low risk of drug interactions.8
Antidiabetic drugs have numerous interactions. A good practice is to use a drug­—drug interaction checker if any questions arise. Several are available online, and pharmacists can scan medication profiles quickly for interactions (and are happy to do so). Quality care starts with the clinician obtaining a complete medication list for each patient at the start of each visit.
Lauren Trahan is a PharmD candidate at the University of Connecticut in Storrs.