Re Herb-Drug interactions and adverse effects

[Guest guest]

Hi All,

 

Any volunteers to do a detailed Medline search for papers on:

(a) Drug-Herb interactions, and

(b) documented adverse events (undesirable side effects) of herbal

medicines?

 

For example, see the articles, below.

 

Best regards,

Phil

 

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Miller LG. Herbal medicinals: selected clinical considerations

focusing on known or potential drug-herb interactions. Arch Intern

Med. 1998 Nov 9;158(20):2200-11. Comment in: Arch Intern Med.

1999 May 24;159(10):1142-3. Arch Intern Med. 1999 Sep

13;159(16):1957-8. Department of Pharmacy Practice, Texas Tech

University Health Sciences Center, Amarillo 79121, USA. Herbal

medicinals are being used by an increasing number of patients who

typically do not advise their clinicians of concomitant use. Known

or potential drug-herb interactions exist and should be screened

for. If used beyond 8 weeks, Echinacea could cause hepatotoxicity

and therefore should not be used with other known hepatoxic

drugs, such as anabolic steroids, amiodarone, methotrexate, and

ketoconazole. However, Echinacea lacks the 1,2 saturated necrine

ring associated with hepatoxicity of pyrrolizidine alkaloids.

Nonsteroidal anti-inflammatory drugs may negate the usefulness of

feverfew to treat migraine headaches. Feverfew, garlic, Ginkgo,

ginger, and ginseng may alter bleeding time and should not be

used concomitantly with warfarin sodium. Additionally, ginseng

may cause headache, tremulousness, and manic episodes in

patients treated with phenelzine sulfate. Ginseng should also not

be used with estrogens or corticosteroids because of possible

additive effects. Since the mechanism of action of St John wort is

uncertain, concomitant use with monoamine oxidase inhibitors and

selective serotonin reuptake inhibitors is ill advised. Valerian should

not be used concomitantly with barbiturates because excessive

sedation may occur. Kyushin, licorice, plantain, uzara root,

hawthorn, and ginseng may interfere with either digoxin

pharmacodynamically or with digoxin monitoring. Evening primrose

oil and borage should not be used with anticonvulsants because

they may lower the seizure threshold. Shankapulshpi, an Ayurvedic

preparation, may decrease phenytoin levels as well as diminish

drug efficacy. Kava when used with alprazolam has resulted in

coma. Immunostimulants (eg, Echinacea and zinc) should not be

given with immunosuppressants (eg, corticosteroids and

cyclosporine). Tannic acids present in some herbs (eg, St John

wort and saw palmetto) may inhibit the absorption of iron. Kelp as

a source of iodine may interfere with thyroid replacement therapies.

Licorice can offset the pharmacological effect of spironolactone.

Numerous herbs (eg, karela and ginseng) may affect blood glucose

levels and should not be used in patients with diabetes mellitus.

Publication Types: Review Review, Tutorial PMID: 9818800

[PubMed - indexed for MEDLINE]

 

Rigelsky JM, Sweet BV. Hawthorn: pharmacology and therapeutic

uses. Am J Health Syst Pharm. 2002 Mar 1;59(5):417-22. H. H.

McGuire Veterans Affairs Medical Center, Richmond, VA, USA.

The uses, pharmacology, clinical efficacy, dosage and

administration, adverse effects, and drug interactions of hawthorn

are discussed. Hawthorn (Crataegus oxyacantha) is a fruit-bearing

shrub with a long history as a medicinal substance. Uses have

included the treatment of digestive ailments, dyspnea, kidney

stones, and cardiovascular disorders. Today, hawthorn is used

primarily for various cardiovascular conditions. The cardiovascular

effects are believed to be the result of positive inotropic activity,

ability to increase the integrity of the blood vessel wall and improve

coronary blood flow, and positive effects on oxygen utilization.

Flavonoids are postulated to account for these effects. Hawthorn

has shown promise to treat New York Heart Association (NYHA)

functional class II congestive heart failure (CHF) in both

uncontrolled and controlled clinical trials. There are also

suggestions of a beneficial effect on blood lipids. Trials to establish

an antiarrhythmic effect in humans have not been conducted. The

recommended daily dose of hawthorn is 160-900 mg of a native

water-ethanol extract of the leaves or flowers (equivalent to 30-169

mg of epicatechin or 3.5-19.8 mg of flavonoids) administered in two

or three doses. At therapeutic dosages, hawthorn may cause a

mild rash, headache, sweating, dizziness, palpitations, sleepiness,

agitation, and gastrointestinal symptoms. Hawthorn may interact

with vasodilating medications and may potentiate or inhibit the

actions of drugs used for heart failure, hypertension, angina, and

arrhythmias. The limited data about hawthorn suggest that it may

be useful to treat NYHA functional class II CHF. Publication Types:

Review Review, Tutorial PMID: 11887407 [PubMed - indexed for

MEDLINE]

 

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The EU Drug Boards assess issues of SAFETY, EFFICACY and

QUALITY-CONTROL in the registration process of new drugs. The

issue of SAFETY will be crucial for the official acceptance of herbal

medicines in the EU.

 

Failure of the herbal profession to address these issues head-on

will be another nail in the coffin of natural medicines in EU. We

cannot leave it to " our enemies " to do those assessments in a

totally fair and unbiased way.

 

Experts from the herbal profession must assess the SAME DATA

as our opponents, and interpret it fairly.

 

" Our interpretation " must highlight

(a) the risk-benefit ratios (in comparison to those of allopathic

treatments) and

(b) OTHER factors (such as pre-existing organ compromise, such

as liver cirrhosis, early renal- or heart- failure, etc) that may have

played a role in adverse outcomes to herbal Tx.

 

IMO, the SAFETY of herbal medicines will be assessed on two

main criteria: (1) The nature and frequency of adverse reactions in

subjects taking herbal medicines, and (2) Herb-Drug interactions.

 

If these issues are addressed professionally and scientifically, and

the data show risk levels at or below those from currently used

allopathic drugs, I believe that a very strong case may be made for

the acceptance of herbal medicine.

 

 

Best regards,

 

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