ADV PCOGNOSY 2, UNIT1, PCG SEM2 notes Herbal Remedies – Toxicity and Regulation Herbal drugs vs Conventional drugs Efficacy of Herbal medicine products Validation of Herbal therapies Pharmacokinetic issues by herbal drugs Pharmacodynamic issues by herbal drugs

1. ADVANCE PHARMACOGNOSY
- 2
M PHARM – PHARMACOGNOSY
SEM 2 UNIT 1
S. PRITHIVIRAJAN., M. Pharm
Dept. of Pharmacognosy, COP,
Madurai Medical College,
Madurai-20

2. CONTENTS
1. Herbal Remedies – Toxicity and Regulation
2. Herbal drugs vs Conventional drugs
3. Efficacy of Herbal medicine products
4. Validation of Herbal therapies
5. Pharmacokinetic issues
6. Pharmacodynamic issues

3. Herbal Remedies
 Herbal remedies are plants based medicine to help prevent or cure disease.
 They use them to get relief from symptoms, boost energy, relax, or lose
weight.
Herbal Remedies can be prepared in form of Infusions, Herbal Teas,
Decoction, Syrups, Tinctures, Pills, capsules.powders, etc.
Herbal remedies are a type of dietary supplement. They are not medicines.
Herbals are not regulated like medicines. Herbals do not need to be rigidly
tested before they are sold. Herbals may not work as claimed. Labels do
not need to be approved. It may not list the correct amount of an ingredient.
Some herbal remedies may contain contaminants.
It is considered medicinal only when it has the pharmacological activity of
possible therapeutic use.

4. Toxicity in Herbals and their Interactions
Some plant descriptions in traditional herbal medicine (e.g.
traditional Chinese medicine) have changed over time, which may
lead to unintended intoxication by using wrong plants.
A problem is also the contamination of herbals with
microorganisms fungal toxins such as aflatoxin, with pesticides
and heavy metals Unprofessional processing, which differs from
safe traditional preparation represents another potential source for
herbal poisoning.
Unwanted effects of herbal products may also develop by the
interaction of herbs with conventional drugs upon concomitant
intake

5. The art of herbal medicine is to dissect pharmacologically and
therapeutically valuable herbal drugs from harmful and toxic ones and to
develop combinations of medicinal plants as safe and efficient herbal
remedies.
Standardization and strict control measures are necessary to monitor
sustainable high quality of herbal products and to exclude contaminations
that badly affect patients consuming herbal medicine.

6. Herbal Drugs vs Conventional drugs

7. Herbal drugs are phytochemical compounds used for the treatment of many
diseases. Herbs have active ingredients which act as drugs e.g. opiate,
digitalis, and taxol.
Herbs/medicinal plants/homemade remedies are less expensive than
synthetic drugs. Most people in rural/backward areas have faith in Herbals.
This is because they can treat any disease without any lethal side effects.
Even they are also widely used for enhancing the beauty and for curing
skin-related issues
Synthetic drugs are synthesized in the laboratory These are the medicines
that are not found in nature. Although herbal medicines are less potent in
comparison to synthetic drugs

8. Herbals are considered less toxic or have fewer side effects in
contrast to synthetic drugs. The ultimate norm for any medicine
(human-made or natural) is its non toxicity, effectiveness,
specificity, stability, and potency.
Now many chemists switching their field from synthetic to natural
side to explore nature more and more.
Synthetic drugs not only cure the disease but also causes severe
side effect to the human body.
e.g. Paracetamol causes liver poisoning (a major side effect).
Naproxen causes gastrointestinal side effects. Ibuprofen -causes
nephrotoxicity including renal failure

9. Efficacy of Herbal medicine products
Herbal drugs and their constituents have advantageous effects on long-term
fitness and can be used to efficiently treat human diseases or disorders.
 In veracity, herbs frequently include various active ingredients that
imaginably have drug allying commotion in the body.
Bringing into play, herbs are often more affordable than procuring expensive
contemporary pharmaceuticals to take care of ailments. A large number of
herbs have proved their usefulness in managing various illnesses.
Latest advances in biology and medicine have introduced new technologies to
study the biological significance of herbal drugs in various human diseases
and disorders. Hence it is important to understand the mechanism(s) of herbal
drug action for the knowledge and development of successful therapies.

10. Validation of Herbal Therapies
 Validation is the action of checking or proving the validity or accuracy
of something. All medicines, should fulfill the basic requirements of
being safe and effective
The main obstacle to the growth of herbal medicine is its quality
control.The scientific validation by standardization, evaluation of purity,
and demonstration of its efficacy in animal models and in humans will
increase the trust of users and increase its acceptability.
Standardization requirement is because of Variation in Plant materials.
The guidelines issued by WHO for quality control of Herbal drugs are,

11. 1. Authentication (stage of collection, parts of the plant collected,
regional status, botanical identity like phyto-morphology,
Microscopical and histological analysis. taxonomical identity, etc.)
2. Foreign matter (herbs collected should be free from soil.insect parts or
animal excreta, etc.)
3. Organoleptic evaluation (Sensory characters-taste. Appearance, odour,
feel of the drug, etc.) Tissues of diagnostic importance present in the
drug powder.
4. Volatile matter, Moisture content determination.
5. Chromatographic and spectroscopic evaluation.
6. Determination of heavy metals-e.g. cadmium, lead,arsenic, etc.
7. Pesticide residue, Microbial contamination, Radioactive contamination

12. Pharmacokinetic interactions
i) Absorption:
Interactions affecting absorption result in a reduction/increase of the
absorption of the drug. Changes in intestinal pH, complexing mechanisms and
drugs affecting intestinal motility will affect absorption.
For example, herbs such as aloe leaf, guar gum and senna, whichare
common ingredients in herbal weight-loss products, exert a laxative effect that
may decrease intestinal transit time and reduce drug absorption
ii) Distribution
A drug with high plasma protein binding (eg. warfarin, carbamazepine)
that has a small volume of distribution may be displaced by a herb competing
for the same binding sites.

13. Drug displacement from protein-bound forms, by concurrent drug
administration, causes an increase in serum drug levels and which may lead
to an increase in therapeutic effect.
iii) Metabolism
Enzyme Induction - A decrease in the amount of drug could occur by
stimulating the production and activity of enzymes that degrade the drug
and prepare it for elimination from the body.
Enzyme Inhibition - The opposite may also occur, in which the herb
inhibits the production of the enzyme required to break down the drug.
hence increasing the drug levels. Unlike enzyme induction, which may take
several days or weeks to develop fully, enzyme inhibition can occur within
2-3 days resulting in a rapid development of toxicity.

14. Concurrent use with drugs like alprazolam, simvastatin, calcium-
channel blockers, and protease inhibitors could potentially increase serum
drug levels and adverse effects.
iv) Excretion
Changes in excretion may also affect serum drug levels. Herbal diuretics
are quite weak and unlikely to cause large problems.
However, chronic ingestion of licorice may result in hypokalemia
and water retention and accordingly may interfere with various
medications including anti-hypertensive and antiarrhythmic agents.

15. Pharmacodynamic Interactions Additive interactions
A herb might produce the same kind of effect as the drug and give
effect it is without increasing the amount of drug but increase in the drug
activity, like herbal sedatives, anticoagulants, anti-hypertensive & others
may possibly increase the effect of a concurrent, conventional drug taken for
the same purpose.
For example, the hypnotic activity of benzodiazepines is increased by
valerian, and the anticoagulant action of warfarin is enhanced by gingko,
garlic and ginger

16. Antagonistic interactions
A herb might produce an effect that is contrary to the effect desired for the drug,
thereby reducing the drug effect. Ephedra or caffeine-containing herbs often used with
cardiovascular effect substances in herbal weight-loss products, may antagonize the
effects of antihypertensive medications.
Effects Pharmacodynamic Herb-Drug Interactions on Various Systems of Body:
GIT: Horse chestnut acts as irritant to GIT & can affect efficacy of anti ulcer drugs.
Activity of laxatives may be enhanced by use of senna.
CVS: Antihypertensive drugs may be adversely affected by use of ginseng & dandelion.
Alfalfa enhances effect of hypo lipidaemic drugs.
CNS: Sedative herbs react with hypnotic & anxiolytic drugs. Evening primerose oil can
react with epileptogenic drugs.
Endocrine system: Ginseng & red clover can interfere with activity of sex hormonal
treatment & oral contraceptives.