Drug Interactions Flashcards
Name the 4 strong inducers of CYP 3A4. (PPFC)
Phenytoin, Fosphenytoin, Carbamezapine, phenobarbital
How does dexamethasone affect methadone?
Decrease efficacy of methadone.
Cipro affect on methadone/fentanyl? Preferred floxacin abx?
Cipro inhibits CYP3A4 causing increased levels of methadone/fentanyl. Preferred Levaquin.
Effects of Erythro and clarithromycin? Alt mycin abx?
Inhibit CYP3A4, causing increase drug levels and potency. Consider Azithromycin.
Name the -Azoles with sig drug interactions? What is effect on CYP3A4?
Fluconazole, voriconazole, posaconazole. Inhibit CYP3A4.
Adverse effect to watch out for Buproprion?
Can lower seizure threshold
St. Johns Wort indication? Effect on CYP? Important AE?
Tx for depression, Inducer, can cause serotonin syndrome.
Grapefruit effect on CYP? What meds does it affect?
Inhibit, increase doses of statins
What is 1st line tx for opioid induced itching?
Diphenhydramine (Benadryl)
What age should pts taking TCA be screened with EKG?
40 years or older
True/false. Respiratory acidosis increases effect of opioids?
False, Resp Alkalosis can increase transmission to cross BBB.
What is Rifampin effect on CYP?
Inducer, increase breakdown of meds making less effective.
Effect of TCA on methadone?
Increase methadone’s effect
What to worry about when starting Meperidine?
It can cause seizures due to its metabolite.
What is one advantage of clonidine?
It can decrease postoperative oxygen consumption.
Which class of meds should be used cautiously if pt also taking L-tryptophan?
SSRI can cause serotonin syndrome.
What meds should be avoided with buprenorphine?
Antiarrhythmics
Weird SE of glucocorticoids?
Hiccups.
What herbal medicine has some effect in helping chemotherapy induced fatigue? What meds should be used cautiously with this herb?
American Ginseng, interacts with anticoagulation meds
What is indication for Kava-Kava?
Anxiety, possible benefit.
What is indication for Ginkgo biloba?
Dementia, but not shown to be beneficial.
What are some important SE of megace? 3
VTE, adrenal insufficiency, male androgen deficiency
What 3 chemo drugs are highest emetogenic?
Cisplatin, cyclophosphamide, dacarbazine.
Of the 3 which meds can cause sexual dysfunction and decreased libido? Buspar, Buproprion, opioids?
Opioids.
What are the 4 “A’s” when initiating chronic opioids?
Analgesia, Adverse effects, Aberrant behaviors and Activity.
True/False.
Methylnaltrexone crosses the blood brain barrier?
False, it is quaternary structure so it doesn’t.
Which NSAID has greatest risk of CV risk?
Diclofenac.
Olanzapine blocks what receptors for nausea?
serotonin, histamine, dopamine, and acetylcholine.
What drug is 6-MAM a metabolite of?
Specific to heroin.
Which opioid is least likely to cause bradycardia?
Meperidine, it can cause tachycardia.
Which TCA has the least SE?
Nortriptyline.
What drug metabolizes into meprobamate?
Carisoprodol (soma), used as antispasmodic
In neonates, how are opioids different compared to adults?
Neonates have decreased clearance leading to prolong half life of opioids.
Which NSAIDs are available parenterally?
Meloxicam, ibuprofen, ketorolac, diclofenac
True/False about lidocaine patch?
- Caution in use with antiarrhythmics/local anesthetic?
- Needs dose escalation and tolerance builds quickly?
- Safe to use in severe hepatic disease and works quickly?
- True
- False
- False
Nortryptiline and desipramine are what class of of TCA?
Secondary amine and have more favorable SE profile/ less anticholinergic effects.
Linezolid has odd MOA, what is MOA and can lead to what condition?
MOA-inhibitor, leads to serotonin syndrome with other serotonin agents.
Drugs/classes that can cause serotonin syndrome?
15 drugs
SSRI, MAOi, meperidine, fentanyl, TCA, triptans, carbamazepine, valproic acid, tramadol, lithium, St. Johns wort, ritonavir, metaclopramide, zofran.
What is oral to intrathecal ratio conversion of morphine?
1 intrathecal : 10 epidural.
1 epidural : 10 IV
1 IV : 3 mg Oral
What SE should you be worried about when starting baclofen?
lower seizure threshold
What is most common SE of modafinil (provigil)?
Headaches
What is MOA of cyclobenzaprine? What other drug class is it similar to?
Inhibits norepinephrine reuptake and serotonergic reuptake. Similar to 1st gen TCA.
Which SSRI can be stopped abruptly due to it’s long half life?
Fluoxetine.
True/false.
Meperidine is not affected by renal insufficiency?
Meperidine has an active metabolite?
False. AKI increases bioavailability
True, it can lead to seizures/serotonin syndrome
True/False.
- Methylnaltrexone induces opioid withdrawal?
- What is absolute contraindication to starting methylnaltrexone?
- False
2. Bowel obstruction, it can cause bowel perf.
What common SE can be seen in Tramadol?
Hypoglycemia
