What are the potential interactions between acyclovir, albuterol, alendronate, azelastine, buspirone, cyanocobalamin, cyclobenzaprine (Flexeril), ergocalciferol, ezetimibe (Zetia), fluticasone/vilanterol/umeclidinium (Trelegy), fluvoxamine (Fluvox), folic acid, memantine, metoprolol, mirabegron, mirtazapine, potassium, and pravastatin?

From the Guidelines

I strongly advise consulting a healthcare provider for a comprehensive medication interaction check, as the combination of acyclovir, albuterol, alendronate, azelastine, buspirone, cyanocobalamin, cyclobenzaprine, ergocalciferol, ezetimibe, fluticasone/vilanterol/umeclidinium, fluvoxamine, folic acid, memantine, metoprolol, mirabegron, mirtazapine, potassium, and pravastatin may lead to significant interactions, including increased risk of serotonin syndrome, enhanced sedative effects, and reduced medication effectiveness. The potential interactions among these medications are complex and multifaceted. For instance, cyclobenzaprine (Flexeril) and fluvoxamine (Fluvox) may increase the risk of serotonin syndrome, a potentially life-threatening condition 1. Additionally, metoprolol and mirtazapine may enhance each other's sedative effects, leading to increased drowsiness and impaired cognitive function. Some key considerations include:

• Buspirone and fluvoxamine can increase buspirone levels, potentially causing dizziness and drowsiness
• Metoprolol and albuterol may reduce the effectiveness of both medications
• Alendronate requires specific administration timing to avoid interactions with other medications and supplements, particularly calcium-containing products like ergocalciferol (vitamin D)
• Potassium supplements should be monitored when taken with metoprolol to avoid hyperkalemia These interactions occur because many of these medications are metabolized by the same liver enzymes, compete for protein binding sites in the bloodstream, or have opposing mechanisms of action, as noted in the context of polypharmacy management in older patients 1. Some medications may also affect the absorption or elimination of others, altering their effectiveness or increasing side effect risks. Given the complexity of these interactions, it is crucial to prioritize a comprehensive medication review to minimize potential harms and optimize therapeutic benefits, particularly in the context of managing morbidity, mortality, and quality of life.

From the FDA Drug Label

DRUG INTERACTIONS Cyclosporine: Combination increases exposure of ezetimibe tablets and cyclosporine. Cyclosporine concentrations should be monitored in patients taking ezetimibe tablets concomitantly. Fibrates: Coadministration of ezetimibe tablets with fibrates other than fenofibrate is not recommended until use in patients is adequately studied. If cholelithiasis is suspected in a patient receiving ezetimibe tablets and fenofibrate, gallbladder studies are indicated, and alternative lipid-lowering therapy should be considered. Bile Acid Sequestrants: Cholestyramine combination decreases exposure of ezetimibe tablets.

The potential interactions between ezetimibe and other medications are:

• Cyclosporine: Combination may increase exposure of both ezetimibe and cyclosporine, requiring monitoring of cyclosporine concentrations 2.
• Fibrates: Coadministration with fibrates other than fenofibrate is not recommended until further studies are conducted 2.
• Bile Acid Sequestrants (e.g., Cholestyramine): Combination may decrease exposure of ezetimibe 2. There is no information about interactions with acyclovir, albuterol, alendronate, azelastine, buspirone, cyanocobalamin, cyclobenzaprine, ergocalciferol, fluticasone/vilanterol/umeclidinium, fluvoxamine, folic acid, memantine, metoprolol, mirabegron, mirtazapine, potassium, or pravastatin in the provided drug label.

From the Research

Potential Interactions

• Acyclovir, albuterol, alendronate, azelastine, buspirone, cyanocobalamin, cyclobenzaprine (Flexeril), ergocalciferol, ezetimibe (Zetia), fluticasone/vilanterol/umeclidinium (Trelegy), folic acid, memantine, mirabegron, potassium, and pravastatin do not have documented interactions with other medications in the provided studies.
• Fluvoxamine and mirtazapine can interact to cause serotonin syndrome, as documented in a case study 3.
• Mirtazapine can also interact with other medications, such as venlafaxine 4 and olanzapine 5, to cause serotonin syndrome.
• Metoprolol can interact with certain antidepressants, such as paroxetine, fluoxetine, and bupropion, which are potent CYP2D6 inhibitors, to increase the risk of severe bradycardia and atrioventricular block 6.
• The combination of metoprolol with antidepressants that are moderate to strong CYP2D6 inhibitors, such as fluoxetine, paroxetine, duloxetine, or bupropion, can increase the risk of hemodynamic adverse events, including hypotension, bradycardia, and falls 7.

Medication-Specific Interactions

• Fluvoxamine:
  • Can interact with mirtazapine to cause serotonin syndrome 3.
• Mirtazapine:
  • Can interact with fluvoxamine to cause serotonin syndrome 3.
  • Can interact with venlafaxine to cause serotonin syndrome 4.
  • Can interact with olanzapine to cause serotonin syndrome 5.
• Metoprolol:
  • Can interact with paroxetine, fluoxetine, and bupropion to increase the risk of severe bradycardia and atrioventricular block 6.
  • Can interact with antidepressants that are moderate to strong CYP2D6 inhibitors to increase the risk of hemodynamic adverse events 7.