Medication/Herbal Interactions

Folk medicine has existed since the beginnings of humanity. People are always in search of safer options than modern medicine to reduce potential risks and to minimize side effects, so more and more they turn towards the use of medicinal herbs.

Medicinal plants are widely used around the world and almost 30% of the world's population is very fond of them. However, this category of people use medicinal plants, vitamins, and doctor-prescribed medications all together without having the proper information about the interactions between medications and medicinal plants. As a result, these patients may risk interactions.

Almost 50% of patients, when in need of medical visit, forget to tell the doctor about the herbal preparations they are taking. It is the duty of health professionals, whether a doctor or pharmacist, to provide health education to patients on the correct way of choosing herbal products so that their combination with contemporary pharmaceutical preparations results in no negative interactions to the detriment of the patient.

Medicinal plants can be used in combination with medications to maximize the benefit for the patient as much as possible. For example, in diabetics who are normally treated with their antidiabetic preparations, adding herbal preparations containing lutein, which increases the microcirculation of the eye, significantly contributes to the reduction of diabetic retinopathy. This herbal treatment is not considered a cure for the disease in question but together with contemporary medications, it contributes to reducing the risks associated with this disease.

It is not entirely possible for doctors or pharmacists to give the patient absolute assurance about the safety of a herbal product for no negative interactions with medications. But they can give them highly valuable guidelines based on the information we have.

Some of the measures taken to minimize unwanted interactions are:

• monitoring the medicinal plant and the medication at the same time
• monitoring the possible negative effect
• monitoring the possible interaction between them

Medications can interact in 2 ways :

1. Pharmacokinetic interaction:

• Change in gastrointestinal pH (change in acidity in the stomach can significantly impact the absorption of medications.)
• Absorption is another issue of equal importance regarding overdoses and their pharmacokinetics.
• Changes in gastrointestinal motility
• binding with proteins. This can indicate how ready a medication is for absorption. For example, horse chestnut binds with plasma and proteins and competes against Warfarin, a medication used to prevent blood clotting.
• changes in the process of metabolism and elimination of drugs have their own impact on increasing or decreasing the therapeutic effect of medications.
• the interaction may involve a medicinal plant that may increase or decrease the amount of the medication in the bloodstream
• the reduction in the amount of medication may occur as a result of the binding of some components of the medicinal plant with the medication and inhibiting it from entering the bloodstream from the gastrointestinal tract.
• the reduction in the amount of medication in the bloodstream as a result of interaction may lead to the ineffectiveness of this medication (in not achieving the therapeutic effect)
• an increase in the amount of medication in the bloodstream may reach levels at which the side effects of the medication may significantly increase.

2. Pharmacodynamic interactions

Pharmacodynamics is the way a medication acts on a tissue or an organ. These interactions result in the improvement or worsening of effects.

For example, Hypericum perforatum or St. John's Wort acts as a stimulator of the liver enzyme system. This system is responsible for the metabolism of a large number of medications, so stimulating or strengthening this system can reduce the plasma concentration of many medications.

When we stop taking St. John's Wort, it takes at least 3 weeks for the liver enzymes to return to their normal function.

Grapefruit inhibits the transport of proteins and acts as a pump for the movement of medications through the cell wall, so high concentrations can be reached for many medications. Consuming grapefruit juice simultaneously with doctor-prescribed medications can significantly increase the availability of the medication in the organism. This can lead to an excessive increase in effect and benefit (e.g., antihypertensive medications, greatly lowering blood pressure, causing dizziness to the point of fainting) or increase in side effects. This effect in the case of grapefruit lasts over time, so it is necessary to avoid its consumption during the use of these medications.

The pharmacist should make a note (warning) on the prescription table for those (medications) that are restricted, but may include them (medicinal plants in the case of grapefruit) in the case of cholesterol-lowering medications, oral contraceptives, some hypnotic tablets, and even Viagra.

Other factors that influence interaction include: age, genetics, ethnicity, liver or kidney damage, smoking, etc.

Medications with a narrow therapeutic spectrum have always been used for specific needs of the organism, therefore their use together with medicinal plants may disturb their balance in the organism.

Cases of interactions between medications and drugs can include:

1. DIGOXIN. Some laxative preparations such as Aloe vera reduce the amount of potassium in the organism and thereby increase the toxicity of digoxin
2. THEOPHYLLINE. Any herbal preparation that has a stimulating effect, such as caffeine including guarana, can have an additional effect on the central nervous system and can increase the levels of theophylline.
3. LITHIUM. Medicinal herbal products with a diuretic effect including caffeine can be a serious problem for the effectiveness of lithium in the organism.
4. WARFARIN. The risk of bleeding increases with the use of medicinal plants that contain coumarin (Black cohosh, chamomile) or antiplatelet effect (fish oil, vitamin E, ginger, garlic, red cranberry)
5. ST. JOHN'S WORT and sunlight can cause photosensitivity especially when combined with other photosensitizing medications like antibiotics (ciprofloxacin)
6. KAVA KAVA has become the herbal answer to Valium in America. It helps in calming the brain and relaxing the muscles without causing side effects like sedation or addiction. However, kava is not safe for everyone. Taking it with alcohol can intensify the effect of alcohol. Kava can interact with anxiolytics such as benzodiazepines and anesthetics. Kava should be avoided in use by patients taking antipsychotic drugs and levodopa.
7. GINKGO and ASPIRIN Increase the inhibition of blood clotting, making it possible to develop hemorrhages. Ginkgo can be used to improve blood microcirculation. It is also neuroprotective and antioxidant and helps in improving concentration.
8. ST. JOHN'S WORT and DIGOXIN. reduces the absorption of digoxin making it possible to reduce its effectiveness.
9. GARLIC and WARFARIN. Increases the inhibition of platelet aggregation thus increasing the possibility of bleeding.
10. GINKGO and WARFARIN increase the inhibition of platelet aggregation. Ginkgo is a widely used herbal preparation as a remedy against aging, contributing to blood microcirculation, heart diseases, sexual impotence, and in increasing mental capacity and especially memory. Ginkgo also enhances the effect of aspirin

Bibliography

1. http://nccam.nih.gov/
2. Encyclopedia of Herbal Medicine: The Definitive Home Reference Guide to 550 Key Herbs with all their Uses as Remedies for Common Ailments by Andrew Chavallier
3. http://www.who.int/mediacentre/factsheets/fs134/en/