Drug Interactions Exam #01 Flashcards
Acidophilus
Transplant patients on immunosuppressants should avoid probiotics b/c introducing live bacteria into an immunocompromised system.
If taking ABO, probiotic effects will be negated (if susceptible). Recommend starting probiotics at tail end of ABO therapy
Lactobacillus acidophilus is a gram(+) anaerobic rod
Chasteberry (Agnus castus)
Uses:
Menstrual disorders and fertility
MOA:
DA agonist and estrogenic effects
DDI:
Enhances other DA agonist drugs for PD like bromocriptine, pergolide (Permax®), pramipexole (Mirapex®), and ropinirole (Requip®) resulting in too much DA which can cause change in mental status and signs of schizophrenia
Counters other DA antagonist drugs for schizophrenia like olanzapine (Zyprexa®), risperidone (Risperdal®), clozapine (Clozaril®)
Additive with estrogen
Opposes tamoxifen
Alfalfa
Uses: nutrients and vitamins
MOA:
Possible immunostimulation
DDI:
Case report of transplant rejection from immunostimulation
Warfarin - alfalfa is rich in Vit K
Aloe vera
Uses (for oral formulation only):
DM
DDI:
Additive hypoglycemic effect with drugs that lower glucose
Aristolochia (Birthwort)
Uses:
Childbirth panacea, pain and inflammation, snake bites
MOA:
KNOWN NEPHROTOXIN
DDI:
Combined nephrotoxic effects with drugs known to cause harm or that affect renal hemodynamics (NSAIDs, ACE-I, ARB)
Ashwagandha (winter cherry)
Uses:
Sedative, possibly DM
MOA:
Possible BG lowering, thyroid properties
DDI:
Additive effect with levothyroxine
Counter effect with anti-thyroid drugs like propylthiouracil, methimazole (Tapazole®)
Betacarotene (precursor to Vit A)
Uses:
Age-related eye disorders, antioxidant
DDI:
Orlistat (Xenical®) indicated for obesity reduces fat absorption - leads to reduced absorption of fat-soluble vitamins (including betacarotene)
Heavy alcohol use - interferes with conversion of betacarotene to vitamin A via CYP2E1 (competition of induction)
Diminishes effects of increasing HDL in patients on simvastatin + niacin
Bilberry
Uses:
Diarrhea, hemorrhoids, venous insufficiency, GI disorders
MOA: possible anti-platelet activity
DDI:
PD interaction with other antiplatelet or anticoagulant drugs
Ephedra (ma huang)
Banned by the FDA
Uses:
weight loss, stimulant, increased concentration, enhanced athletic performance
MOA: CNS and cardiac stimulant, stimulates uterine contractions, peripheral vasoconstriction
Bitter orange
This was manufacturers response to ephedra ban
Uses:
same as ephedra
MOA:
sympathetic alpha-adrenergic agonist
DDI:
inhibits CY3A4
Black cohosh
Use:
Peri- and post- menopausal Sx. Recent studies show no real benefit.
MOA:
Estrogenic properties
DDI:
Additive estrogenic drugs
Counters anti-estrogenic drugs
Caffeine
Sources of caffeine:
Seeds of guarana, tea leaves, nuts of cola
Metabolized by CYP1A2
DDI: Inhibitors of 1A2 like Fluvoxamine (Luvox®) Cimetidine (Tagamet®) Disulfuram (Antabuse®) Cipro® Norfloxacin Clozapine
ASA - Caffeine increases the AUC, Cmax and rate of absorption of ASA
Adenosine (vasodilator) - caffeine is an adenosine antagonist (vasoconstrictor)
Bitter Orange - increased risk of severe cardiac AE
Cat’s Claw
Use:
dyspepsia, antispasmodic, arthritis, herpes, HIV, and contraceptive
MOA: antiplatelet and antihypertensive effects
DDI:
Potent 3A4 inhibitor
Chamomile
Use:
dyspepsia, travel sickness
MOA:
contains a natural coumarin
DDI:
warfarin - additive effect
Chondrointin
Use:
OA
Structurally similar to heparin so may have additive anticoagulant properties
Coenzyme Q10
Use:
cardiac health, prevent statin-induced myopathy, antioxidant
DDI:
NO clinically significant interaction with warfarin
Cranberry
Use:
urinary antiseptic
DDI:
does NOT affect PK of drugs like cyclosporine or warfarin
Echinacea
Use:
immune system booster
AVOID in patients on immunosuppressive therapy and patients with autoimmune disease
Evening Primrose Oil
Use:
arthritis, chronic fatigue syndrome, menopausal Sx, ADHD, asthma/cough
DDI:
Can inhibit platelet aggregation and increase bleeding time. No data supporting interactions with other antiplatelets
Feverfew
Use:
prophylaxis and tx of HA and migraines
MOA:
Structurally related to NSAID and has anti-inflammatory properties. Inhibits platelet aggregation in vitro and has potential interactions with anticoags and antiplatelets such as ASA, clopidogrel (Plavix®), prasugrel Effient®, Ticagrelor (Brilinta®)
Garlic
Use:
respiratory infections, CV disorders
Benefits from garlic come from eating raw chopped garlic. Crushing garlic releases and destroys Alliin (the active ingredient) which makes gelcap and capsule formulations useles
DDI:
May have interaction with antiplatelet drugs and warfarin, but interaction is over-hyped
Ginger
Use:
N/V
DDI:
Does NOT increase anticoagulant effect of warfarin and no evidence of antiplatelet interactions
Ginkgo
Use:
improve memory and cognitive function
MOA:
Has antiplatelet effects and may affect CYP enzymes
DDI:
VPA and phenytoin - risk of seizure - Ginkgo seeds contain a neurotoxin which inhibits activity of glutamate which results in seizure induction by lowering GABA levels OR induction of 2C19
Anti platelet drugs - many case reports of increased bleeding
Omeprazole - Ginkgo induces 2C19
Ginseng
Use:
improve mental and physical performance, energy booster
DDI:
Warfarin - possible decrease effect
Estrogen - may contain estrogenic properties so additive or antagonistic with estrogens and anti-estrogens, respectively; plus case reports of vaginal bleeding
Hawthorne
Use:
“Cardiotonic” for weak heart. Morons try to treat HF with this
Horse Chestnut
Use:
Tx of varicose veins as both topical and oral products
MOA:
has antiplatelet activity
DDI:
antiplatelet drugs
Licorice (dried licorice root and extracts, not candy)
Use:
expectorant, antispasmodic, anti-inflammatory
MOA:
Has mineralocorticoid effects including Na and H2O retention and K+ excretion leading to HTN and hypokalemia
DDI:
PD interactions with digoxin, laxatives, and diuretics
Milk Thistle
Use:
“liver tonic,” used by nursing mothers for milk production
Active constituent = silymarin
DDI:
Silymarin inhibits 3A4 - caution w/ NTI 3A4 substrates
St. John’s Wort
Use:
mild to moderate depression
DDI:
Potent 3A4 inducer (and many others)
Cyclosporine/Tacrolimus - risk of organ rejection
Protease Inhibitors - reduction in serum PI levels
Oral contraceptives - treatment failure
Warfarin - decreased INR
Methadone - tx failure and withdrawal Sx
Voriconazole - reduced efficacy
PD interactions:
Serotonin syndrome
Photosensitivity
Green Tea
Potential interaction w/ warfarin b/c contains small amount of vitamin K, but brewing tea destroys some of the vitamin K
Valerian
Use:
Sedative/hypnotic
DDI:
enhanced sedative effects with alcohol, BZD, barbiturates
White Willow Bark
Major component is salicin which is metabolized to salacylic acid (caution in ASA allergy)
DDI:
other antiplatelet and anticoagulant medications
Herbal meds to D/C prior to surgery
- Ephedra (ma huang) - 24 hr
- Kava - 24 hr
- Ginkgo - 36 hr
- St. John’s Wort - 5 days
- Garlic - 7 days
- Ginseng - 7 days
Digoxin
Goes by many names; from foxglove plant. Earliest sign of digoxin toxicity is bradycardia
Which herbals/dietary supplements interact w/ warfarin and can increase INR and bleeding risk?
Alfalfa Chamomile Feverfew Ginseng Horse chestnut Willow
Over-hyped Interactions: Chondroitin* Garlic* Ginger* Ginkgo*
Which herbals/dietary supplements interact w/ warfarin and can decrease INR reducing effects of warfarin?
St. John’s Wort
Green tea
Which herbs that contain tannin can counter effects of iron supplementation and lead to anemia?
Chamomile Black Cohosh Saw Palmetto Feverfew St. John's Wort Valerian
Which of the following can potentially adulterate herbal medications and dietary supplements?
A. Botanicals B. Toxic metals C. Drugs D. A & C E. All of the above
E. all of the above + microorganisms and pesticides have also been found to be contaminants in herbals/dietary supplements
Federal Food, Drug, and Cosmetic Act of 1938
Drugs must be tested for safety and efficacy before being marketed. Drugs being used before 1938 were grandfathered in and didn’t have to prove safety/efficacy
Shirley Amendment of 1912
No false labeling claims
Food and Drug Act of 1906
Prohibited shipment of adulterated or misbranded drugs across state lines
T/F - the majority of botanicals are classified as OTC?
True - even though they have pharmacologic activity
OTC categories
Cat I - safe and effective
Cat II - not recognized as safe and effective
Cat III - insufficient data
Most herbals are Cat II
DSHEA (dietary supplement health and education act)
Established first legal definition of dietary supplement - product intended to supplement the diet and contains a vitamin, mineral, amino acid, herb or other botanical as capsule, powder, soft gel or gel cap (NOT injection)
“This product is not intended to Dx, Tx, cure or prevent any disease”
