Herbal Remedies and Drug
Interactions
JEANNA M. HICKS MSN, RN
OCTOBER 2010
A Bit Of History
 The practice of herbal medicine is as
old as mankind itself
 Every human culture on every
continent has practices it in one form or
another
A Bit Of History
 About 25% of today’s drugs contain
ingredients isolated from plants
 Salicylic acid (Aspirin) is derived from
while willow bark
 Vincristine (A form of chemotherapy)
 Morphine is derived from the opium
poppy
A Bit Of History
 In the US, botanical products are now a
$1.5 billion per year industry
 It is estimated that 60 to 70% of the
American population is taking
botanical products
 However less than one third of these
inform their medical practitioners of
their use
A Bit Of History
 Because herbs are sold as food
supplements, companies are not
required to prove their efficacy.
 Side effects or interactions are also not
required to be determined or disclosed.
 No government agency reviews these
products for safety, dosage, or quality.
A Bit Of History
 In 1994, the Dietary Supplement and
Health Education Act (DSHEA) was
enacted.
 Created the new category of dietary
supplements.
 This exempts herbal products from the
rigorous safety and efficacy testing
required by the FDA.
A Bit Of History
 Manufacturers and distributors may
now market any herbal or botanical
product without prior approval by the
FDA as long as the label does not claim
effectiveness for the treatment or
prevention of a specific disease.
 Must have a disclaimer stating that the
FDA has not evaluated the product.
A Bit Of History
 The manufacturer alone is responsible
for quality control.
 The burden of proof regarding safety
issues lies with the FDA.
A Bit Of History
 Many products are perfectly safe.
 However, 2621 adverse events
associated with dietary supplements,
including 101 deaths, were reported to
the FDA over a 5-year period.
Common Pitfalls
 Multiple ingredients are present in the
same bottle.
 Products are sometimes mislabeled or
misidentified
 Potency can vary depending on the
climate and soil in which the herbs are
grown.
Common Pitfalls
 When a drug is prescribed, the dosage
and quality of the product is more or
less assured.
 This is not the case with herbs since
there is no real quality control.
Drug-Herb Interactions
 Pharmacokinetic interactions : Having
to do with absorption, distribution, and
metabolism.
 Pharmacodynamic interactions:
Additive activity meaning that certain
herbs increase the actions of certain
medications.
Pharmacokinetic Interactions: Absorption
 Some herbs have hydrocollated
carbohydrate components such as
gums and mucliage.
 These are soluble in water but poorly
absorbable.
 Examples are psyllium, rhubarb,
flaxseed, and marshmallow.
Pharmacokinetic Interactions: Absorption
 Bind to other drugs, particularly when
consumed in their whole or powdered
forms.
 Psyllium inhibits the absorption of lithium.
 Rhubarb and aloe can cause diarrhea
which reduces the actions of drugs that
have a narrow therapeutic index (digoxin,
warfarin)
Pharmacokinetic Interactions: Absorption
 In order to prevent an herb from
binding with drugs, the drug should be
taken one hour before or two hours
after these herbal products.
Pharmacokinetic Interactions: Distribution
 Meadowsweet and black willow contain
pain reducing salicylates.
 These may displace highly protein bound
drugs such as warfarin and carbamezepine
(Tegretol).
 This increases the adverse effects of these
drugs.
 Do not take these products concurrently
Pharmacokinetic Interactions: Metabolism
 When taken as an herb, licorice
decreases the metabolism of
corticosteroids.
 This leads to adverse and toxic effects
from the buildup of corticosteroids.
 St. John’s wort increases the
metabolism of drugs in the liver.
Pharmacodynamic Interactions
 Additive activity
 The hypnotic activity of
benezodiazepines is increased by
valerian.
 Anticoagulant action of warfarin is
enhanced by ginko
Ginkgo (Ginkgo biloba)
 Used by elderly persons because of its
ability to improve cognitive function in
persons with Alzheimer’s and
dementia.
 Reports of bleeding associated with
ginkgo use have been reported.
Ginkgo (Ginkgo biloba)
 Patients ranged from 33 to 78 years old
 One person was taking no other drugs
concurrently.
 Others were taking aspirin, warfarin,
acetaminophen, or an ergotaminecaffeine preparation concurrently.
 Episodes were both minor and major
 One death from cerebral hemorrhage.
Gingko (Gingko biloba)
 Caution patients who are also taking
Vitamin E, warfarin, aspirin, and low
molecular weight heparin about the
potential interactions with ginkgo.
 If taking ginkgo, counsel them to report
any unusual bleeding, bruising, or an new
onset of dizziness, headache, or blurred
vision to their healthcare provider.
Flaxseed (Linum usitatissimum)
 Flax is one of the oldest cultivated plants in
the world.
 A bulk-producing, stool softening agent
that lowers levels of cholesterol,
triglycerides, and low-density lipoproteins.
 Binds to bile acids in the intestinal tract
and interferes with the reabsorption of fats.
Flaxseed (Linum usitatissimum)
 When soaked, flaxseeds can bind with
other drugs, especially cardiac glycosides
rendering them unabsorable.
 Take flaxseed wither two hours before or
two hours after taking other meds.
 Concurrent use with laxatives and stool
softeners should be avoided because of
possible potentiation of the laxative effect.
Feverfew (Tanacetum parthenium)
 Most commonly used to reduce the
number and severity of migraine
headaches.
 Inhibits platelet activity, so it should not be
taken concurrently with warfarin or other
drugs that affect clotting.
 A member of the daisy family, it is
contraindicated in patients with allergy to
ragweed.
Ginger (Zingiber officinale)
 Used and tested as an antinausea and
antispasmodic agent with good results.
 Potent inhibitor of thromboxane
synthetase.
 Prolongs bleeding times.
 If taking warfarin or other drugs that
affect platelet activity, avoid ginger in
tablet form.
Kava Kava (Piper methysticum)
 Relieves anxiety, nervousness, and
tension.
 Does not affect alertness.
 Acts as a dopamine antagonist.
 May increase tremor and decrease
response to anti-Parkinsonian meds.
Kava Kava (Piper methysticum)
 Potentiates alcohol
 Potentiates tranquilizers
 Potentiates antidepressants
 Do not take any of these concurrently
with Kava
St. John’s Wort (Hypericum perforatum)
 One of the most popular herbs in the
US for the treatment of depression.
 Current research shows that it acts as a
selective serotonin reuptake inhibitor
(SSRI)
 Because of this, concurrent use with
SSRIs is prohibited.
St. John’s Wort (Hypericum perforatum)
 Patients should wait 2 weeks after taking
an SSRI before beginning St. John’s wort.
 Newest research suggests that it may act in
the cytochrome P-450 of the liver.
 Interferes with metabolism of certain
protease inhibitors used in the treatment of
HIV.
St. John’s Wort ( Hypericum perfortum)
 Associated with photosensitivity.
 Do not take concurrently with other
photosensitizing herbs or drugs.
 If taking St. John’s wort, limit sun
exposure.
Implications For Anesthesia and Moderate
Sedation
 Morbidity secondary to botanical
product use may be more prevalent in
the perioperative period because of
multiple drug use and increased
physiological susceptibility to adverse
effects.
Implications For Anesthesia and Moderate
Sedation
 The problem is complicated by patients’
reluctance to report their use of herbal
medicines or dietary supplements.
 70% of presurgical patients failed to
disclose their use of such products
during routine preoperative
assessment.
Reasons For Not Reporting Use of Herbal
Medications
 A belief that because such products are
“natural,” they must be safe.
 Fear of how healthcare providers would
respond to self-medication.
 Fear that their physician may be
prejudiced against use of botanicals.
Adverse Effects
 Cardiac Instability
 Electrolyte disturbances
 Prolonged bleeding
 Excessive sedation
Cardiovascular Effects of Anesthesia
 Decreased myocardial contractility
 Decreased vascular smooth muscle tone
 Arrhythmias
 Decreased cardiac output
 Avoid botanicals with blood pressure
altering or arrhythmogenic potential
Ephedra Alkaloids
 Also known as ma-huang
 Common ingredient in many herbal
weight loss and energy boosters
 Often packaged in combination with
guarana (caffeine)
 Use has been linked to hypertension,
palpitations, tachycardia, seizures,
stroke, heart attack, and sudden death.
Ephedra Alkaloids
 Ephedra has been identified as the
herbal product with the greatest
potential for harm in perioperative
patients.
Prolonged Bleeding
 Feverfew
 Ginger
 Gingko
 Horse chestnut
 Pau d’arco
 Danshen
 Garlic
 Saw palmetto
Prolonged Bleeding
 Gingko has been linked to a
spontaneous hyphema in a 70 year old
man who took 40mg of Gingko extract
twice a day along with 325 mg of
Aspirin daily for one week.
 Also bilateral subdural hematomas in a
33 year old woman who took 60 mg of
Gingko twice a day for two years.
Prolonged Bleeding
 Certain herbs increase INR
 Danshen
 Dong quai (Used primarily in China but
gaining popularity in the US)
 Paparin
Prolonged Bleeding
 Certain herbs contain coumarin or
coumarin derviatives
 Angelica root
 Anise
 Licorice
 Red clover
 Rue
Prolonged Bleeding
 Antiplatelet activity
 Tumeric
 Clove
 Onion
 Bromelain
 Willow bark
 Meadowsweet
Excessive Sedation
 Any herb with inherent sedative effects can
potentially delay emergence from
anesthesia.
 Sedative herbs include kava, hawthorne
and St. John’s wort.
 There has been a report of an interaction
between kava and alprazolam that resulted
in a semicomatose state.
Excessive Sedation
 St. John’s wort is believed to have some
of the same effects as MAOIs.
 MAOIs may result in hypotension and
exaggeration of the respiratory and
CNS depressant effects of the narcotics.
 Because of this St. John’s wort should
be discontinued before a procedure
where narcotic analgesia is anticipated
Excessive Sedation
 Valerian is a popular herb used as a
sleep aid and anxyiolytic.
 An extract of valerian containing valeric
acid has been shown to prolong
barbituate induced sleeping time.
 Considered safe as a food additive but
has the potential for prolonging
sedation.
Echinacea
 Used to boost the immune system and
guard against colds and flu.
 May cause hepatotoxicity especially
when used with certain hepatotoxic
drugs.
 Examples are methotrexate or anabolic
steroids.
Echinacea
 Many medications used during
anesthesia are metabolized in the liver.
 Hepatic dysfunction may be a risk in
certain patients who use echinacea.
Ginseng
 Used to support overall health and
boost the immune system.
 May also be used to increase stamina,
promote a sense of well-being, control
blood pressure, and lower blood
glucose levels.
 Excessive use may cause hypertension,
and CNS stimulation.
Ginseng
 May also reduce opioid’s analgesic
effects.
 May cause hypoglycemia in patients
taking insulin or oral diabetic agents.
 Monitor blood glucose levels closely in
patients who have been taking ginseng.
 May increase warfarin’s anticlotting
effect.
Guarana
 Marketed as a CNS stimulant.
 Contains a high concentration of
caffeine and is found in many
antifatigue products.
 If taken in combination with SNS can
cause cardiac arrest.
 May also decrease cerebral blood flow
Nursing Implications
 Patients are reluctant to reveal their use
of dietary supplements to their health
care providers.
 Caregivers should be aware of the many
potential interactions with patients
undergoing anesthesia or moderate
sedation.
Nursing Implications
 Make sure to get an accurate,
nonjudgmental, and thorough history
of all medication use.
 Encourage the patient to discuss their
use of herbals.
 This screening should be a routine part
of all preanesthetia screening.
Nursing Implications
 This screening should take place far
enough in advance to allow for
discontinuation of potentially
dangerous interactions.
 Patients should discontinue their
herbal preparations at least two to
three weeks before surgery.
Nursing Impications
 Safe, effective care requires awareness of
all your patients’ use of herbal supplements
and knowledge of their potential
interactions with anesthestics and drugs
used during moderate sedation.
 Include all medications when reviewing
your patients’ meds before their procedure.