Class Notes (839,460)
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PHAR 100 (175)


5 Pages

Pharmacology and Toxicology
Course Code
PHAR 100
Hisham Elbatarny

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Herbal Medicines Introduction • drugs derived from many sources ◦ 20 to 25% of prescription drugs derived from plants • herbal sales probably approaching two billion • ⅔ of world population depends on herbal medicines Relevance • over ¼ (perhaps1/2) of the Canadian adult population have taken a natural health product in the past year. • more than 1/2 of Canadians using complementary or alternative medicine do not disclose this to their physicians. • increasing number of natural health products for sale in Canada • most of these are sold through stores (including mail order) other than pharmacies • potential adverse interactions with conventional treatments • the potential for this increases when the doctor does not know that the patient is taking NHP Definitions • allopathic medicines: main stream drugs approved by Health Canada. (DIN) • herbal medicines: plant products sold as medicines – no approval • allopathic phytopharmaceuticals: compound or drug obtained from plants but full approval • homeopathy: the lower the concentration the greater the effect • food supplement: herbal product at ¼ the proposed therapeutic dose Why the move to herbals? • concern over the toxicity of allopathic medicines • high cost of allopathic medicines ◦ 50$ -200 000$ for prescription • lack of faith in allopathic medicines • hope for a cure for a chronic or terminal illness ◦ once cancer/other reoccurs for a third time ◦ amygdalin for cancer ▪ isolated from apricot seed, cyano compound ▪ said to be effective against some types of cancer (~20-30yrs ago) ▪ Cancer Society in US did clinical trials: no efficacy • belief that herbals are non-toxic ◦ not true • magic bullet: concept where always looking for key factor, one critical factor, that triggers cell to become a cancer cell • eventually have a target drug, the magic bullet, that will take out this factor • most lethal substance: anthrax force Value of plants for pharmaceuticals • direct source for therapeutic agent, e.g. Digoxin • source for raw materials for synthesis, eg. estrogens • structure of plant substance used as a model for new compounds ◦ cancer chemotherapy – Taxols. Problems Associated with Herbals • lack efficacy data ???? → not data show that they work, studies that have been done haven't been done with the same rigor as prescription drugs • lack safety data ???? • lack of quality control → being addressed: new regulation in 2004 • undeclared ingredients • intentional adulteration • source unknown and questionable • confusing literature -- what standards to be used ◦ want: same standards for prescription drugs • toxicities – some innocuous, others not • drug interactions with allopathic drugs Regulatory control • limited • should herbals be classed as drugs? • less regulatory control than OTC drugs Valerian - “herbalists' diazepam” • sedative and hypnotic ◦ contains valepotriates – shown to have CNS depressant activity with less adverse effect than diazepam • effect on sleep (From Trials) ◦ no difference in onset ◦ no difference in REM sleep -- which is good. ◦ no difference in quality of sleep vs placebo ◦ other studies small benefit – may be useful in mild insomnia – placebo? • safe but not effective – systematic review ◦ systematic review: look at all of studies being published ▪ make restrictions for which studies they are going to look out (ex: randomized, etc) Valerian continued Statistically significant vs Two studies. (2011) clinically significant • sleep quality in postmenopausal women ◦ placebo 4% reported improvement in sleep quality index ◦ valerian 530 mg 30 % reported improvement • Valerian in cancer patient. (RDBPC) ◦ 450 mg valerian vs placebo and measured PSQI (Philadelphia sleep quality index) over 8 weeks --- no difference in sleep Ex:when began to treat pneumonia w/ penicilin → in some ◦ controlled trial populations mortality rate ofpneumonia was hi
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