Medication Interactions Elizabeth Rash PhD, ARNP, FNP-C UCF College of Nursing CFP Physicians Group

Medication Interactions Good and Bad – Synergism Ex. Codeine + acetaminophen or ibuprofen = increased pain relief – Adverse drug events (ADEs) A B Unidirectional A B Bidirectional

Adverse Drug Events (ADEs) The numbers (U.S. Prescribing 2003) 3.4 billion Rx filled – 10.1 million/yr for <65y – 23.5 million/yr for >65y

Adverse Drug Events (ADEs) 701,547 patients treated for ADEs in EDs ( ) – 116,318 hospitalized – 1/3 2 o allergic reactions – 1/3 2 o unintentional overdose – 2/3 rd s considered to be potentially preventable

Adverse Drug Events (ADEs) Most ADEs 2 o 5 classes of drugs: – Insulins – Opioids (narcotics) – Anticoagulants – Amoxicillin containing antibiotics – Antihistamine containing cold products JAMA 2006

Adverse Drug Events (ADEs) 21.3% > 65yr (community dwelling) at least 1 inappropriate Rx drug 23% of nursing home admissions due to medication problems (J. Am. Pharm. Assoc.:Nov 2002)

Polypharmacy vs. Polymedicine

Drug Interactions: What? Other drugs – Coumadin® and Erythromycin increase bleeding Food – Grapefruit and Verapamil increase toxicity Herbs and supplements – St. John’s Wort and Zoloft® increase serotonin crisis risk Other medical conditions or diseases – Prednisone® and Diabetes increase blood sugar

Drug Interactions: How? Absorption – Can slow down or speed up how rapidly the drug gets into the blood stream Ex. antacids + tetracycline

Drug Interactions: How? Meta bolism enzymes – Inducers: speed the metabolism of another drug and can cause ineffectiveness – Inhibitors: slow the metabolism of another drug and can cause toxicity or ineffectiveness Plavix® and PPIs (Prilosec®) – PPI inhibits the action of Plavix® a Prodrug that does not work until it Is metabolized

Drug Interactions: How? Receptors – Some drugs block the tissue receptors that stop other drugs or chemicals from having action on that tissue Could be good or bad – Ex. Antihistamines (Claritin®) block allergens on the histamine receptors stopping allergic reactions – Ex. Antihistamines (Ditropan®) block the cholinergic receptors and interfere with Alzheimer’s drugs like Aricept from working 

Drug Interactions: How? Elimination – Taking an aspirin (acidic pH) with Zegerid® (basic pH) may cause more rapid elimination of the aspirin and decrease its effect

Drug Interactions: How? Timing – NSAIDs (Motrin®) interfere with the platelet benefits of a preventive Aspirin. If taking both, take the aspirin first and wait at least 2 hours before taking the Motrin®

Common Drug Interactions Antifungal drugs that end in "-azole”, Itraconazole or Sporanox®) Some antibiotics (end in "-mycin” Erythromycin®) Antacids cimetidine (Tagamet®) Drugs that prevent convulsions, (Dilantin® and Tegretol®). Cholesterol drugs such as statins (Lipitor®) Blood thinning drugs (Coumadin®)

Drug Interactions: Preventing ADEs Brown bag or drug list to all providers ID bracelets Use 1 pharmacy Pharmacist consultation Communicate side effects and don’t stop abruptly without discussing with provider Follow instructions

Questions? Thank you! CFP Physicians Group 985 SR 436 Casselberry Fl (407)