Drug Interations

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Drug Interations
2011-05-05 00:36:13
Drug Interactions

Drug Interactions
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  1. Explain the MOI b/w non-cardioselective beta-blockers and epi
    • Alpha 1 ag: vasocon
    • Beta 1 ag: cardiac +
    • Beta 2 ag: vasodil
    • *w/non-selective beta-blocker, beta-ag is blocked leaving unopposed alpha-1 reflex inc. in vagal tone, HTN
    • *Limit epi to .04mg/2hr visit
  2. Discuss the MOI b/w oral contraceptives and systemic antibiotics
    • Estrogens from BCP's are conjugated in liver and secreted into intestine where normally intestinal bacteria cleave the conjugate so that free estrogen can be reabsorbed
    • Antibiotics dec. the # of intestinal bacteria and therefore dec. plasma estrogen concentrations
    • *Note: progesterone does not interact with dental antibiotics
  3. List significant interactions w/NSAIDS
    • Anticoagulants (Warfarin = 2 AVOID, coumadin)- inc. risk of bleeding disorders in anticoag. pt
    • Antihypertensives (ACE -,etc)- dec. anti-HTN effect, monitor BP
    • Lithium carbonate- inc. lithium levels, use sulindac
    • Methotrexate- toxicity may be inc., monitor
    • Salicylates- dec NSAID levels w/inc GI effecs, AVOID CONCURRENT USE
  4. List significant interactions w/epi
    • TCA (high dose only) -inc sympathomimetic effects, limit epi to 0.04mg
    • Non-cardioselective beta-blockers (3)- HTN and cardiac rxn possible
    • Alpha-1 blocking antipsychotics
    • MAOI- slight possibility of HTN rxn
    • COMT - (for parkinson's disease)- slight possibility of HTN rxn
    • *Epi+alpha-1, beta-1, beta-2 agonist = min change in MAP & mild inc in HR
    • *Epi+beta-blocker = HTN, inc vagal tone
  5. Explain why macrolides and azole antifungals have so many drug interactions
    • They are potent INHIBITORS of CYP3A4 which is responsible for probably the highest number of biotransformation rxns
    • Ex: Fluconozole/OC - can dec OC effectiveness due to dec in estrogen
    • Metronidazole/alcohol -can lead to food poisoning type effects
    • Clarithromycin/CCBs -QT interval elongation-->sudden death
  6. Clinical screening for drug interactions in dentistry
    • Category 1: avoid concomitant use
    • Category 2: avoid if alternative is available and if used, close monitoring
    • Category 3: avoid if alternative is available and if used, some monitoring
    • Category 4: potential for harm is low so drug combo CAN be used