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Herbal medicine


Natural or botanical health products

Overview of usage of herbal products for health

Different Types of Herbal Products

  1. Supervised by health care practitioners

  2. As self-care products, self-directed use (NPHs regulations)

Issues with Botanical Health Products

  1. Concern about predictable quality and health benefit?

  • Biological effects are induces by secondary plant metabolites, which are produced by plants for self-defense, survival…

  • Levels are influenced by various stresses:

  1. Environmental conditions

  2. Soil conditions

  3. Seasonal effects

  4. Harvesting and Productions methods

  5. Microbial & chemical Contaminants.

  1. Efficacy (health claims) and safety depend on sourcing, harvest practices, processing, manufacturing, and storage.

Canadian regulations introduced. Natural and Non-prescription Health Products Directorate (NNHPD) of Health Canada

What are NHPs?

Traditional medicine plus:

  1. A plant or plant materials, fungus or non-human animal materials

  2. An extract of a)

  3. A vitamin

  4. An Amino Acid

  5. An Essential Fatty Acid

  6. A Mineral

  7. A Probiotic (Eg. Acidophilus)

For OTC use only. All products have to be licended.

New regulatory framework is being proposed

What can we expect of these licensed products?

Licencing requirements:

  1. Data for Pre-marketing assessment:

  • Quantity of medicinal ingredients and specification compliance with GMP… product quality

  • Health claims

  • Safety and Efficacy data

  1. Post market monitoring of adverse events and report to Health Canada

Level of evidence required is different depending on: Traditional use Vs Non-traditional use

Three Levels of Health Claims for Non-traditional use:

  1. Risk reduction: Reduce the risk of developing a specific disease or condition by altering a recognized risk factor. (oxidant stress and antioxidants).

  2. Structure-function claims: the effect on a structure or physiological functions of human body E.g. “Maintains healthy gums” or “reduces blood cholesterol levels” or “improve liver function”.

  3. Treatment/therapeutic claims: diagnosis, treatment and mitigation or prevention of a disease, disorder, or abnormal physical state or its symptoms in humans.

Safety Issues of NHPs “Rate of Adverse Health Effects – Low” Much lower than drugs


  • Consumers: Consider these products as natural and therefore safe

  • Some physicians consider NHPs are placebos… thus reduces the like hood of associating any adverse reaction with any NHP usage.

  • Patients are embarrassed to admit the actual amount used when there is an adverse reaction

  • Report of adverse reactions to NHPs by health-care professionals can adverse Drug Reaction Monitoring Program

  • Case report: difficult to establish causal relationship


Product Factors affecting efficacy and safety

  1. Lack of quality control

  2. Contaminations: bacteria and fungi, pesticides, heavy metals, radioactive residues

  3. Wrong substitution: wrong her being incriminated

  4. Adulterants:

Eg. Asian Patent medicines

*Usually contain multiple components

*Contains prescriptions drugs, heavy metals, and other ingredients that may or may not be listed on the label.

Consumer Factor affecting efficacy and safety: Inappropriate use by consumers

  1. Misconceptions and over-dosing

“All natural health products are ‘safe’ “ and “More is better”.

  • Consume excessive doses.

  • E.g. Miss-use of weight loss and energy/tonic products

  • May contain diuretics, laxatives and caffeine, ephedrine and amphetamines.

  • Chronic use >> overdose and toxicity.

  • E.g. Cu 30mg/day for 3 years and 60 mg/day for 1 year >> Liver cirrhosis, hepatic failure.

  • Max dose is 3 mg/day!

“Multiple products exposure”

  • E.g. Zn overdose and Leukocyte aplasia from:

  • 5 different products: Vitamins, minerals, fish oils/linoleic acid, amino acids, and enzymes >> A total Zn of 36 mg/day – over twice recommended dose.

  1. Herb-Drug Interactions

Most people who use NHPs also take drugs at the same time; and do not tell their physician about it.

Who may be at risk to H-D interaction?

  • Chronic conditions or life-threatening prognoses: cancer, HIV, Alzheimer’s disease, irritable bowel syndrome, chronic fatigue syndrome

  • Frustrated with conventional medications: patients from rheumatology, hemodialysis, organ transplant.

Examples of Clinically Significant Interactions, according to mechanisms:

  • Pharmacokinetic interactions: herb alters the pharmacological effects/toxicity by modifying the plasma concentration of the drug via changes in:

  • Absortion

  • Distribution

  • Ecretion

  • Metabolism

  • Pharmcodynamic interactions: herb alters the response of the drug target without changing the drug plasma concentration.

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