Interactions

Indication

A reason to use a certain treatment

Contraindication

A reason not to use a certain treatment due to the harm that it could cause the patient

What are Drug-drug interactions?

When 2 or more drugs react with each other

What is Addition?

The combined effect of 2 drugs is equal to the sum of the effects of each drug taken alone (1 drug can add to the effects or side affects of another drug)

What is Antagonism?

The action of one drug antagonizes (blocks or works against) the action of another drug

What is Potentiation?

One drug enhances or prolongs the effect of another drug

What is Synergism?

The combined effect of two drugs is greater than the sum of the effect of two drugs

What are Drug-disease interactions?

Occurs when a drug that is intended for therapeutic use causes certain harmful effects because of a disease or pre-existing condition that the patient has

• Certain diseases or conditions may alter the absorption or elimination of some medications

What are Drug-nutrient interactions?

Occur when certain foods or beverages increase or decrease the effects of drugs in the body

What are Drug-herbal interactions?

Occur when herbal or dietary supplements increase or decrease a drug’s effects

• Natural or plant-based products are not always safe, especially when co-administered with certain medications

What are Drug-alcohol interactions?

Occur for two main reasons

• Alcohol can have chemical reactions with the drug molecule itself

• Alcohol can have additive harmful side effects with some harmful side effects with some drugs that are central nervous system (CNS) depressants

What are Drug-laboratory interactions?

Medications can interfere with laboratory testing and cause incorrect results

• Can lead to missed or wrong diagnoses and unnecessary testing

What is Grapefruit juice?

• Drug-nutrient interactions

• Inhibitor of enzyme CYP3A4 - responsible for metabolism of many different types of meds

• Co-administration will decrease the metabolism of the drugs, leading to an excess amount of drug in the bloodstream and potentially leading to adverse effects

What medications should not be co-administered with grapefruit juice?

Alprazolam, Amiodarone, Atorvastatin, Calcium channel blockers, and Carbamazepine

What is Warfarin?

• Drug-nutrient interaction

• Blood thinner (works by indirectly inhibiting vitamin K - essential vitamin for blood clotting)

• Green leafy veggies are rich in vitamin K = co-administration can reduce the blood thinning effect of warfarin

What are Dairy foods?

• Drug-nutrient interaction

• Milk and yogurt & Calcium and other minerals like magnesium, aluminum and iron can interact with certain medications by binding to them and preventing their absorption

• Drugs should be separated from dairy/mineral containing products by at least 2-4 hours

What are the drugs that interact with calcium and other minerals (e.g. multivitamins, antacids)?

Bisphosphonates: alendronate, Fluoroquinolone antibiotics: ciprofloxacin, levofloxacin, and Levothyroxine

What is Gingko biloba?

• Drug-herbal interaction

• A herbal supplement

• Increases the risk of bleeding

• Could create an additive risk of bleeding when it is co administered w/ NSAIDs, warfarin, clopidogrel (antiplatelet medication)

What is St. John’s Wort?

• Drug-herbal interaction

• A herbal supplement, used to treat depression

• Increases the adverse effects of several classes of antidepressants

• Also decreases the effectiveness of HIV antiviral medications

What is Metronidazole (FlagylⓇ)?

• Drug-alcohol interaction

• An antibiotic

• Contradicted w/ alcohol because of a “disulfiram-like” reaction that causes severe vomiting and stomach pain

What is Opioid analgesics (e.g. oxycodone, tramadol)

• Drug-alcohol interaction

• Contradicted w/ alcohol because of the risk of additive CNS depression that could result in excessive sedation, respiratory depression, coma, or death

What are thiazide and loop diuretrics?

Can elevate HDL cholesterol levels

What are Barbiturates, Thiazide diuretics, Corticosteroids, and Oral contraceptives?

Can elevate blood glucose levels

What are Beta-blockers, Aspirin, and Trimethoprim/Sulfamethoxazole?

Can decrease blood sugar

What are Thiazide diuretics, Angiotensin-converting-enzyme inhibitors (ACE, or ACEIs), NSAIDS, and caffeine

Can cause hypokalemia (low serum potassium)