herbal remedies and drug interactions

JEANNA M. HICKS MSN, RNOCTOBER 2010

Herbal Remedies and Drug Interactions

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 activityThe 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 oldOne person was taking no other drugs concurrently.

Others were taking aspirin, warfarin, acetaminophen, or an ergotamine-caffeine preparation concurrently.

Episodes were both minor and majorOne 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 alcoholPotentiates tranquilizersPotentiates antidepressantsDo 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 InstabilityElectrolyte disturbancesProlonged bleedingExcessive sedation

Cardiovascular Effects of Anesthesia

Decreased myocardial contractilityDecreased vascular smooth muscle tone

ArrhythmiasDecreased cardiac outputAvoid botanicals with blood pressure altering or arrhythmogenic potential

Ephedra Alkaloids

Also known as ma-huangCommon 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

FeverfewGingerGingkoHorse chestnutPau d’arcoDanshenGarlicSaw 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 INRDanshenDong quai (Used primarily in China but gaining popularity in the US)

Paparin

Prolonged Bleeding

Certain herbs contain coumarin or coumarin derviatives

Angelica rootAniseLicoriceRed clover Rue

Prolonged Bleeding

Antiplatelet activityTumericCloveOnionBromelainWillow barkMeadowsweet

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.