Page 56 - Numero20-2_2017

is often complicated and may sometimes gave unnecessary causations or warnings.
We believed with some general insights in pharmacology of conventional drugs and Chinese herbs; one can foresee possible significant interactions and thus take precautions to avoid incompatibilities and serious result.
1.1 Definition of herb-drug interactions
A possible interaction refers to the possibility that one substance may alter the bioavailability or the clinical effectiveness of another substance when two or more substances are given concurrently. The interaction may result in an increase or a decrease in effect of one (drug or herb) or both substances. Herb-drug interactions may be classified in two major categories: pharmacokinetic and pharmacodynamic interactions. This paper focuses primarily on the alteration of bioavailability or clinical effectiveness of drugs due to concomitant use of Chinese herbs, although there may be cases of the alteration of bioavailabilityorclinicaleffectivenessofherbsdue to concomitant use of drugs.
Many known drug-drug interactions are documented through actual cases, some, through laboratory experiments of pharmacokinetic studies. However many herb-drug interactions discussed are theoretical or documented through laboratory experiments. Therefore, professional judgment is often necessary when evaluating the clinical significance of a potential herb-drug interaction.
anticonvulsant effects, or antipsychotic effects, interactions that may have a major impact to a patient’s health and life, e.g., carcinogenic effects or failure of contraceptive pills. All potential high risk interactions should be monitored very carefully.
1.3 Definition of pharmacokinetic interactions
It refers to the fluctuation in bioavailability of herb-drug molecules in the body as a result of changes in absorption, distribution, metabolism and elimination.
1.4 Definition of pharmacodynamic interactions
Pharmacodynamic refers to the study the physiological effects of drugs on the body and the mechanisms of drug action and the relationship between drug concentration and effect. Pharmacodynamic interactions refer to the fluctuation in bioavailability of ingested substancesasaresultofsynergisticorantagonistic interactions between herb/drug molecules.
2. Pharmacokinetic interactions
2.1 Absorption
- If taken orally the majority of all absorption occurs in the intestines, where herbs or drugs must pass through the intestinal wall to enter the blood. - Several mechanisms may interfere with the absorption of drugs through the intestines, e.g., acidity, gastro-intestine motility, binding substance and the intestinal flora.
- Most of the interactions due to change in drug or herb absorption may be minimized if the drugs and the herbs are taken separately by approximately two hours or longer, except that due to intestinal flora.
2.1.1 Change of absorption due to change of acidity
The absorption of drugs that are sensitive to pH value may be adversely affected by herbs that may change the gastro-intestine acidity.
- Antacid herbs may increase the pH value of gastric juice. These herbs include Hai Gai Ke (clam shell), Hai Piao Xiao (cuttlefish bone), Mu Li (oyster shell), and Long Gu (dragon bone). Antacid herbs should not be used together with acid drugs such as Nitrofurantoin, 4- Aminosalicylic acid, aspirin, indomethacin, penicillin, Iodide, barbital, Phenytoin Sodium, and Tetracycline. The gastric absorption of mentioned drugs may be decreased.
- Some herbs may increase the acidity and they are often high in organic acids. They include Shan Zhu Yu, Nu Zhe Zi, Jin Yin Zi, Fu Peng Zi, Qing Pi, Chen Pi, Wu Wei Zi, Wu Bei Zi, Bao Shao Yao, Jin Ying Hua, Wu Mei, Shan Za, Zhi Shi, Zhi Ke, and Mu Gua. Herbs that increase acidity should not be used together with antacid drugs.
2.1.2 Change of GI Motility
Chinese herbs that change of GI Motility may affect absorption of some drugs. Chinese herbs
1.2 Clinically-significant interactions
Herb-drug interactions demonstrated through clinical trials, pharmacokinetic studies, or documented case reports involving specific herbs (supplements) and drugs are usually clinically significant.
Clinically significant interactions also include interactions of high risk that may result in an immediate, life-threatening adverse event even if their supporting data is not obtained through the above mentioned sources. These include interactions occurring between herbs and drugs that have sympathomimic effects, cardiovascular effects, diuretic effects, anticoagulant effects, anti- diabetic effects, antidepressant effect,
DIALOGHIDIMEDICINAINTEGRATA estate 2017