1. 15-Minute Pharmacology: Drug Interactions
Matt Ozanich, MHHS, NRP
Director of Pre-Hospital Care
Trumbull Memorial Hospital

2. Disclaimer Always follow local protocols
Always follow administrative policies
Always do what is in the best interest of the patient

3. Objectives Define the categories of drug interactions
Discuss examples of common drug interactions within each category.

4. General Physiology of Interactions
Enzymes / Hormones
Duplication
Competition
Similar Mechanisms
Sensitivity

5. Drug Interactions Duplication
Taking two medications with a similar ingredient
Common examples
OTC Sleep Aids with Cold Medicine
Cold Medicine with OTC Pain Relievers

6. Drug Interactions Antagonism Competitive – binds to common receptor
Non-competitive – alters binding site
The idea is to minimize stimulation of the receptor
Common Examples
Naloxone and Opioids
Romazicon and Benzos
Beta Blockers and Albuterol

7. Drug Interactions Idiosyncratic Reactions
Unique, strange, unpredicted reaction
Typically associated with enzyme or hormone deficiencies
Allergy / Anaphylaxis falls here
Common Examples
Soma (muscle relaxer) paralysis/blindness
Aspirin causing an asthma attack
Sulfa antibiotics causing skin burns

8. Drug Interactions Food Reactions Foods affect metabolism
May block enzymes
May prevent absorption
Common Examples
Milk inhibits tetracycline absorption
Grapefruit juice intensifies benzos, estrogen, statins
Tyramine + MAOIs = hypertensive crisis

9. Drug Interactions Synergism Combined action of two drugs
Common Examples
Sulfa + Trimethoprim = better bacteria killer
Aspirin + Warfarin = spont. Hemorrhage
Captopril + Nitro = enh. BP control in CHF

10. Drug Interactions Potentiation Combined action of two drugs
“Enhanced” synergism

11. Synergism vs Potentiation
1 + 1 = 2
1 + 1 = 3

12. Drug Interactions Potentiation Combined action of two drugs
“Enhanced” synergism
Common Examples
Benzos and Alcohol
Benzos and Ketamine
Opiates and Ketamine
Clonidine and Timolol
Warfarin and Amiodarone
SMZ/TMP and Warfarin

13. Drug Interactions Patient Education Identify compliance with meds
Emphasize importance of compliance
Report compliance to facility
Encourage compliance at home

14. Works Cited
Ament, P. W., Bertolino, J. G., & Liszewski, J. L. (2000, March 15). Clinically Significant Drug Interactions. American Family Physician, 61(6),
Moini, J. (2012). Focus on Pharmacology: Principles for Health Professionals. Upper Saddle River: Pearson.
Sener, S., Eken, C., Schultz, C., Serinken, M., & Ozsarac, M. (2011, February). Ketamine with and without midazolam for emergency department sedation in adults: a randomized controlled trial. Annals of Emergency Medicine, 57(2), doi: /j.annemergmed
Thi, L., Shaw, D., & Bird, J. (2009, March 24). Warfarin potentiation: a review of the "FAB-4" significant drug interactions. The Consultant Pharmacist, 24(3),

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