Herbs and YOU!
From: Alice - June 2004, Volume 7, Issue 6
(reprinted from Canadian AIDS Treatment Information Exchange CATIE)
What are the mechanisms of herb-drug interactions?
"Pharmacokinetic Interactions"
Pharmacokinetic interactions involve changes in the way herbs and drugs move through your body and can alter the amount, or level, of drug(s) in your body. If the interaction increases the level of a drug, you might experience side effects and/or toxicity. If the interaction decreases the level of a drug, it might not work as well, possibly leading to treatment failure and/or drug resistance. There are several places in your body where such interactions can happen.
Stomach (Gastro-intestinal tract) -- When herbs and drugs are taken orally, they are usually absorbed into the bloodstream through the stomach an intestines. Herbs can affect the way in which drugs are absorbed, leading to changes in the amount of drug that enters the bloodstream. For example, some herbs can change the physical environment of the stomach, such as the pH level, while others might chemically bind to drugs, causing them to remain in the stomach instead of entering the bloodstream. Some herbs, such as laxatives, can speed up the digestive process, reducing the amount of time a drug is present to be absorbed by the stomach.
Liver -- Once in the bloodstream, many drugs need to be metabolized (chemically altered) by the liver either in order to become therapeutically active or to be removed from the bloodstream. Your liver, therefore, plays an important role in controlling the level and effectiveness of drugs in your body. Herbal therapies (and drug therapies, too) can change liver metabolism. By inducing or inhibiting liver enzymes, herbs can alter the amount of therapeutically active drug in the blood. This is the most important mechanism for interactions between herbal therapies and anti-retroviral drugs.
Kidney Some drugs are eliminated from the bloodstream through the kidney. Herbs that affect the functioning of the kidney can change the level of drug in the blood. If the herb reduces kidney function, the level of drug may increase. If the herb increases kidney functioning, the level of drug may decrease.
"Pharmacodynamic Interactions"
Pharmacodynamic interactions refer to the mutual actions of herbs and drugs inside the body. When taken at the same time, herbs and drugs may work together (synergistically) or in opposition (antagonistically). For example, separately they can have the same toxic effects, so that when taken together, they cause increased side effects. Many herb-drug interactions fall into this category. Pharmacodynamic interactions are difficult to predict or prevent.
Other drugs Many PHAs are taking other medications in addition to HAART. These can include antibiotics, medications for high blood pressure, depression, heart conditions and diabetes, to name a few. The following herb-drug combinations have the potential for significant interactions. This list is not exhaustive.
• Ginko biloba with anticoagulants• St. John Wort (Hypericum perforatum) with antidepressants, oral contraceptives, anticoagulants and transplant medications
• Kava Kava (Piper methysticum) with alcohol or liver damage
• Devil's Claw (Harpagophytum procumbens), Ginseng (Panax ginseng) or Dong Quai (Angelica sinensis) with warfarin
• Hawthorn (Crataegus Species) with antihypertensive medications, digoxin or antidepressants
Have a healthy respect for nature -- Just because it's natural doesn't mean it's harmless. Many people assume that because they are taking a "natural" product that there are no potential adverse effects, and that dosing recommendations are to be ignored. There are a wide variety of toxic effects of herbs. Avoid taking herbs that have known toxic effects, such as pennyroyal, comfrey, germander and liferoot. HIV infected persons should avoid the long-term use of echinacea, as it may increase the rate of replication of the HIV virus.