The present presentation is about Drug-Herb interactions. The content was delivered at Dr Subhash Technical College for the Refresher course of Pharmacist. The content covers the commonly used herbs and its interactions with commonly used allopathic drugs.

1. DRUG-HERB INTERACTION
Punit R. Bhatt (M. Pharm.)
Research Associate
College of Veterinary Science & Animal Husbandry,
Junagadh Agricultural University, Junagadh

2. Agenda
• Introduction
• Evidence
• Effect of herb on pharmacokinetic
• Effect of herb on pharmcodynemics
• Herbs & bioavailability
• Commonly used drugs

5. Ayurvedic drug
• Prepare as per Ayurvedic
pharmacopoeia.
• Oldest system of medicine.
• Mainly water is used as a
solvent.
• Plants are used as such as a
medicine.
Herbal drug
• Unofficial book Indian
herbal pharmacopoeia.
• Modern trend
• Chemical-based solvents
may be used.
• Specific extract of plant part
may be used.

6.  Herbal drugs + allopathic drug = some
reactions (Pharmacokinetics or
Pharmacodynemics).
Herbs/herbal drugs often given with allopathic
drugs with belief that it will have beneficial
effect.
INTRODUCTION

7. Continue….
About 5 to 20% patients take herbal drugs
because,
1. Naturally available
2. Economical
3. Consideration of safe to use

8. EVIDENCE
1. Animal studies
2. Clinical trials
3. Case reports

9. SOME FACTS
1. Drug interaction is the 4th or 6th cause of
death in the world.
2. About 70 to 80 herbs may increase the risk of
bleeding.
3. Aristolochic acid from Kidamari (Aristolochia
bracteolata)is toxic.
4. Ephedra (somlata) caused more than 54
deaths and 1600 cases of adverse reactions.

10. MAIN REASONS
• Clinicians lack of adequate knowledge about
drug-herb interaction.
• No quality control and assurance for the purity
and safety
• No advance research in this field

11. EFFECT OF HERBS ON
PHARMACOKINETICS
Parameter Increase Decrease
Absorption Ginger Fibers
Green tea Mucilage
containing herbs
Black pepper
Metabolism Guggul Grapefruit juice
Elimination Laxatives Liquorices
Diuretics

12. EFFECT OF HERBS ON
PHARMACODYNEMICS
1. Additive effect: D (A,B)=A+B
2. Synergistic effect: D (A,B)>A+B
3. Antagonistic effect: D (A,B)< A+B

13. Additive effect: D (A,B)=A+B
• Anticoagulant with Gingko biloba

14. Synergistic effect: D (A,B)>A+B
Patient
counseling
Crucial role of pharmacist as
prescribers may not know in-depth
about Gymnema sylvestre.

15. Antagonistic effect:
D (A,B)< A+B
Fluphenazine – Antipsychotic
Flupentixol – Antipsychotic
Procyclidine – Anticholinergic drug used in
parkinsonism.
Patient
counseling

16. Herbs & bioavailability
1. Decrease bioavailability
Phenytoin
Shankh pushpi
Patient
counseling

17. 2. Increase bioavailability
Herbs & bioavailability
Most common bioavailability enhancers
Piperine, from Piper nigrum increases
absorption of PHENYTOIN &
PROPRANOLOL, also slowdowns
elimination of these drugs
Patient
counseling

18. 3. Protection from adverse effects
Herbs & bioavailability
Prior administration of zinger acetone extract
prevents the vomiting occurs due to
cyclophosphamide

19. 4. Enhancement of drug effect
Herbs & bioavailability
BROMELAIN
Higher blood
and tissue
levels when
they are
administered
concurrently.
Patient
counseling

20. OTHER CATEGORIES
• Herbs that interact with liver enzymes
• Herbs that Induction and inhibition of
metabolic enzymes
• Inhibition and induction of transport and
efflux proteins
• Alteration in renal elimination

21. Commonly used herbs
Sometimes called nutraceuticals

22. DISCLAIMER
• All the data presented over here are taken
from the scientific literature/online
resources/books/compendiums.
• All the information is given hereafter, is for the
knowledge-addition of the pharmacists.

23. Aloe vera/ barbadensis
Corticosteroids
Risk of hypokalemia
Diuretics Digitalis/Digoxin
Digitalis toxicity

24. Arjuna bark (Terminalia arjuna)
Beneficial effect with other antihypertensive drugs.

25. Ashwagandha (Withania ashwagandha)
Anti-diabetic action with
conventional drugs
Thyrotoxicosis, as it
increases thyroid hormone
level if taken regularly with
high dose.

26. Capsicum (Capsicum species)
Reduces the absorption
of dietary iron.
Slightly increase the
absorption of
theophylline.

27. Cinnamon (Cinnamomum cassia and
Cinnamomum verum)
May enhance the blood-glucose-lowering effects of
conventional anti-diabetics.

28. Coffee (Coffea arabica)
The development of iron
deficiency anemia in pregnant
women, and reduce the levels
of iron in breast milk. As a
result their babies may also be
iron deficient.
Phenylpropanolamine and
coffee may cause the mania
or mood swing.

29. Fenugreek (Trigonella foenum-graecum)
fenugreek saponin decreases fasting blood-glucose
levels if combine with sulphonyl ureas.

30. Garlic (Allium sativum)
Hypotension with
ACE inhibitors
(prils).
With antiplatelet drugs,
it increases risk of
bleeding. Itself
antiplatelet.
Reduces the
metabolism of
chlorzoxazone.

31. Grape seed (Vitis vinifera)
The concurrent use of grape seed and
ascorbic acid (vitamin C) appears to
increase systolic and diastolic blood
pressure.

32. Liquorice root (Glycyrhiza glabra)
Liquorice may cause fluid
retention and therefore reduce
the effects of antihypertensives.
Additive hypokalaemia may also
occur with loop and thiazide
diuretics.
It may cause the digoxin
toxicity.

33. Pepper (Piper nigrum)
An established bio-enhancer. Piperine is an
alkaloid from the pepper.
In higher dose it may cause the acidity.

34. Senna (Cassia angustifolia)
The risk of hypokalaemia
might be increased in
patients taking
corticosteroids.
patients taking potassium-
depleting diuretics could
experience excessive
potassium loss if they also
regularly use senna.

35. Soya (Glycine max)
Hypertensive reaction may occur with
non-selective MAOs (Monoamine
Oxidase inhibitors) and RIMAs
(Reversible inhibitors of monoamine
oxidase A).

36. Green tea (Camellia sinensis)
Both black and green tea may cause a modest increase in
blood pressure, which may be detrimental to the treatment
of hypertension.

37. Turmeric (Curcuma longa)
Relatively safe. No significant interaction was found between
drug and turmeric.

38. • Medscape drug interaction checker
• https://www.cdc.gov/
• https://www.drugs.com/

39. Hope you don’t have the doubt. If any, please let me know.