PHAR 100 - Module 05

prescription drugs

restricted to sale by prescription only

non-prescription drugs

drugs sold to general public without prescription → over the counter (OTC) drugs 

over the counter drugs

\
* public can diagnose mild symptoms and select appropriate treatment options 
* Not replacement for prescription drugs

guidelines for using OTC drug

1. Illness and/or symptoms

* Familiar with the symptoms (ex: fever for cold) → mild symptoms 
* Serious illness/symptoms should be treated by a doctor 


2. Adverse effects 

* Upon occurrence, stop taking medication immediately due to unknown negative personal effects of interactions with other drugs 


3. Consultation 

* In doubt, ask a pharmacist 
* Self medication should not exceed 2 weeks without seeing a doctor

safety and efficacy of OTC Drugs

\
* controlled by Food and Drugs Act → controls safety, efficacy, advertising
* New OTC products undergo preclinical testing, post-market safety surveillance 
* Not all OTC products have undergone randomized controlled trials 

grandparenting

\
* new regulations do not apply to those products already on the market because they have been used for decades (ex: acetaminophen) 

selection of appropriate OTC drugs

1. proven efficacy and known toxicity
2. simple formulations and ingredients
3. brand vs generic → generic is cheaper but equally as effective
4. appropriate and effective dose → best OTC comes in appropriate dosage

common OTC drugs

\

1. Internal Analgesics 
2. Antihistamines 
3. Drugs for excess stomach acid 
4. Decongestants 
5. Cough supressants 
6. Sleeping aids 
7. Laxatives 
8. Antidiarrheals 
9. Hydrocortisone cream 
10. Sunscreen

common internal analgesics

used for pain relief


1. Acetylsalicylic Acid (ASA - aspirin) 
2. Acetaminophen (Tylenol)
3. NSAIDs (non-steroidal anti-inflammatory drugs)

Acetylsalicylic Acid - Aspirin

\
* Relieves pain, fever, and inflammation: inhibits synthesis of prostaglandins → endogenous substances that enhance mediation of pain and fever 
* Stroke and heart attack prevention: inhibits platelet aggression and clot formation 
* Adverse effects: gastric irritation, tinnitus (ringing in the ears), Reye’s syndrome (affects CNS), allergic reactions

Acetaminophen (Tylenol)

\
* Mechanism of action: inhibits prostaglandin synthetases → forms prostaglandins 
* Therapeutic uses: analgesic (relieves pain), antipyretic (fever reducing), not effective anti-inflammatory 
* Used where ASA causes gastric irritation 
* Adverse Effects: overdose (20 tablets) leads to fatal liver injury 
* Liver injury if therapeutic doses taken for a long time 

NSAIDs (non-steroidal anti-inflammatory drugs) 

\
* Ibuprofen (Advil), naproxen (Aleve) 
* Therapeutic uses: effective analgesic, antipyretic, anti-inflammatory effects 
* Adverse effects: gastric irritation, skin rash, dizziness, blurred vision, fluid retention

when to use topical analgesics?

Topic products can be used for relief of pain from sprains/joint pain 

* Ex: muscle pain cream 

antihistamines

* Used to treat allergy symptoms (hay fever) 


* Drugs block histamine receptors, inhibits binding of histamine to receptors, decreases allergy symptoms 
* First generation antihistamines: cause sedation and drowsiness 
* Second generation: less sedating and preferred agents

drugs used for excess stomach acid

Neutralize stomach acid or decrease stomach acid secretion 


1. antiacids
2. H2 receptor antagonists
3. proton pump inhibitors

antacids

hold pH of gastric contents at 4 → neutralized by acid-base chemical reaction 

* Systemic: orally and absorbed by GI tract (ex: Tums) 
* Ingestion of large amounts can cause hypercalcemia, systemic alkalosis 
* Non-Systemic: orally but not absorbed 
* Does not cause systemic alkalosis but causes constipation

H2 receptor antagonists

Histamine involved in release of stomach acid → secretion involves transfer of protons (H+) into stomach in exchange for potassium (K+) 

what happens without H2 receptor antagonists?

\
* Histamine receptors in acid secreting cells activated
* Proton pump turned on → acid secretion increased

what happens with the H2 receptor antagonist?

\
* H2 receptor antagonists block H2 receptors → reduce amount of acid secreted 
* Adverse effects: skin rashes, headaches, confusion

proton pump inhibitors

\
* Bind to proton pump, inhibit acid secretion by 90% → most effective 
* Low risk of side effects (diarrhea, headache, abdominal pain) 

congestion

caused by dilation of blood vessels which allows fluid to leak from vessels into spaces between cells

decongestants

constriction of blood vessels → prevents accumulation of fluid and reduces congestion (ex: phenylephrine or pseudoephedrine) 

* Long term use causes local irritation and chronic rhinitis → max of 3 uses a day 
* Chronic rhinitis: congested runny nose 
* Adverse effects: rebound congestion, alteration of blood pressure 

cough

signals from bronchioles processed by cough center in medulla of brain

productive cough

clears mucus airways → don’t suppress

non-productive cough

dry cough without phlegm → suppressed

types of cough suppressants

1. centrally acting cough suppressants
2. peripheral cough suppressants

centrally acting cough suppressants

block processing of information in brain → reducing frequency of cough 

* Benylin, dextromethorphan hydrobromide (HBr - first choice), codeine 
* Codeine is an opioid so not preferred 

peripheral cough suppressants

block nerve endings in throat and bronchioles → inhibits stimulus to cough (likely placebo)

* Camphor and methanol added to vaporizes or rubbed on throat and chest

sleep aids

Help individuals fall asleep or relieve sleeplessness


1. Melatonin: hormone in body’s internal sleep-wake system
2. NyQuil, Aleve PM → contain antihistamines to produce sedating effects

laxatives

relieves constipation by softening poop

types of laxatives

1. stimulant laxatives
2. bulk forming and osmotic laxatives

stimulant laxatives

increase motor activity of interestine and increases secretion of mucus, water, and electrolytes into intestines 

* Adverse effects: cramping, dehydration, disturbances in GI tract

bulk forming and osmotic laxatives

stimulates peristalsis → full effect in 2-3 days

* Methylcellulose (bulk forming), polyethylene glycol 3350 


* Adverse effects: water and electrolyte disturbances

antidiarrheal agents

controls diarrhea → associated with dehydration

* cannot be used if diarrhea is accompanied by fever or if there is blood in mucus

types of antidiarrheal agents

1. adsorbents
2. loperamide (preferred)

adsorbents

add bulk to GI tract and absorb toxins 

* Control symptoms of self-limiting diarrhea (resolves on its own)

loperamide

\
* Synthetic opioid that does not penetrate into CNS 
* Inhibits gut motility, reduces peristalsis 
* Mild to moderate non-infectious traveller’s diarrhea (no fever or blood), inhibits cramp 

hydrocortisone cream

\
* topical anti-inflammatory agent used for poisonous plants, insect bites, and inflammation 
* Can also use calamine lotion → more for relief of mild exposure but lacks anti-inflammatory uses  

sunscreens

75% of cancer caused by UV radiation

* sunscreen reduces risk of skin cancer by 40-50%
* recommended sunscreen with sun protection factor (SPF) greater than 30
* types of sunscreens: chemical, physical

chemical sunscreens

\
* Absorbs UV rays before they penetrate into the skin 
* Ex: avobenzone, octisalate 

physical sunscreens

Contain titanium dioxide and zinc oxide which block and scatter UB rays before they enter lower layers of skin

Drug interactions with OTC preparations

\
* OTC can cause drug-drug interactions if drugs affect similar pathway 
* Ex: Antihistamines (CNS depressants) interact with other CNS depressants (alcohol, sedative-hypnotics, opioids) 

combination of ASA and oral anticoagulants (blood thinners)

Together can cause bleeding because ASA prevents platelets from adhering to each other which is needed to stop bleeding 

Antacids

Change pH of stomach acid and coat stomach lining → interferes with absorption of other drugs

Recommended OTC for dental pain

Ibuprofen/Naproxen

Recommended OTC for moderate poison ivy exposure

0\.5% or 1% Hydrocortisone Cream

recommended OTC for heartburn

proton pump inhibitor

recommended OTC for traveler diarrhea

loperamide

recommended OTC for fever in a child

acetaminophen

herbal drugs

plant/plant derivatives used to prevent/treat illness and improve health

* 80% of the world use herbal drugs for treatment of illness

can herbal drugs be toxic?

1. General public: believe that natural products are safer → both natural and man-made can be toxic 

* Ex: botulinum toxin (natural) is severely toxic 


2. Manufacturers and Retailers

* Manufacturers and retailers promote products for financial gain → explains popularity 

history of herbal drugs

\
* Medicine before 1940s depended on natural products (opium) 
* 1950s started to purify natural products → development of synthetic drugs 
* Most drugs today are still derivatives of natural products

classifications of herbal products

1. allopathic medicine
2. herbal medicine
3. phytopharmaceuticals
4. allopathic phytopharmaceuticals

allopathic medicine

mainstream medicine

* Drug identification from Health Canada and has undergone full testing

herbal medicine

plant products without drug identification → lack drug testing

phytopharmaceuticals

drugs obtained from plants that are purified and used at therapeutic doses with documented efficacy 

allopathic pharmaceuticals

drugs obtained and purified from plants that meet drug requirements 

importance of plants for pharmaceuticals

\
* Direct source of therapeutic agents 
* Source of raw material for manufacture of modified semi-synthetic compounds with altered properties → increased efficacy

problems associated with herbals

\
* Lack of randomized controlled trials evaluating efficacy and safety of herbals 
* Need to carefully interpret literature as it efficacy of herbal drugs are often overstated 
* Natural Medicines Comprehensive Database rates effectiveness of herbal products on scale of effective, likely effective, or insufficient evidence

other problems with herbals

1. lack of standardization across similar herbal products
2. intentional adulteration: addition of substances other than herbals
3. differing global standards not coherent with Canadian standards
4. drug interactions with allopathic medicines

common herbal drugs

1. aloe vera
2. devil’s claw
3. st. john’s wort
4. echinacea
5. valerian
6. panax ginseng

aloe vera

aid in healing wounds and burns

devil’s claw

treating inflammatory conditions

st john’s wort

treating mild depression

echinacea

prevention and treatment of common cold

valerian

treatment of nervous tension and panic attacks

panax ginseng

reducing blood sugar, enhancement of memory and learning

how to improve manufacturing and safety of herbal products

\

1. Set appropriate standards for content and purity of active ingredients 
2. Efficacy of products determined in randomized controlled trials 
3. Valid toxicity testing completed 
4. Herbal products that do not possess pharmacological activity need to be compared to current array of allopathic compounds to treat conditions

vitamin

\
* substance essential for maintenance of normal metabolic functions not made in the body → acquired form outside source (important in preventing and treating disease) 
* Initial knowledge of vitamins came from study of disease states 
* Only considered drugs when consumed as a tablet in chemically pure form

water soluble vitamins

Vitamin C and 11 vitamins in B group

fat soluble vitamin

Vitamins A, D, E and K

vitamins as supplements

1. Need for increased nutrition 


2. Absorption disturbances 


3. Inadequate nutritional intake 

approaches to vitamin therapy

1. nutritional approach
2. megavitamin approach

nutritional approach

Individual selects diet aimed at supplying recommended dietary allowance (RDA) for each vitamin or multivitamin preparation

megavitamin approach

\
* Individuals ingest vitamins in excess of RDA 
* Consequences: overdosing of vitamins (B6 overdose causes nerve injury), vitamins A, D, E excess → body fat

vitamin A (fat-soluble) food sources

food sources: Animal products (liver, milk fat, egg yolk), carrots (converted to vitamin A in the body)

functions of vitamin A

growth and development for mucous membrane, epithelial cells, rhodopsin (night vision)

therapeutic uses of vitamin A

administered in infancy, pregnancy, lactation 

* Derivatives used for acne and skin cancers 
* Ex: retinoids (derivative) may cause damage to unborn child, depression, diabetes 

effects of vitamin A deficiency

\
delay of growth and development, night blindness, drying of surface of eye, increases risk for respiratory infection, thick and horny skin 

effects of intensive intake of vitamin A

dry itchy skin, vomiting, headache, enlarged liver and spleen

food sources of vitamin D (fat soluble)

meat, fish, mushrooms, milk

function of vitamin D

increases absorption of calcium and phosphate, regulates blood calcium levels

therapeutic uses of vitamin D

prevents osteoporosis

effects of vitamin D deficiency

decreased absorption of calcium and phosphate from intestine → decreases blood calcium level, defective bones (rickets)

impact of excessive vitamin D intake

elevated calcium blood levels → concerning for kidney/heart disease, causes removal of calcium from bone, fatigue, nausea, vomiting, diarrhea, impaired kidney function 

vitamin e (fat soluble antioxidant) food sources

Tocopherols that are present in vegetable oils and leafy vegetables

function of vitamin e

antioxidant → protect cells in cardiovascular system and other damaging effects of free radicals

therapeutic uses of vitamin E

premature babies with hemolytic anemia (red blood cells destroyer faster than the body produces them)

effects of vitamin E deficiency

rare but can cause malabsorption syndrome 

effects of excessive vitamin e intake

inhibit platelet aggregation → anticoagulant effect

vitamin B12 and B9 (follate → both water soluble)

\
* Vitamin B12: meat, dairy 
* Follate: green vegetables, liver, yeast 

function of B12 and B9

synthesize red blood cells

therapeutic uses of B12 and B9

 B12 supplements, B9 for pregant women to prevent deficiencies in child, prenatal vitamins before pregnancy

impacts of B12 and B9 deficiency

caused by misuse/malabsorption syndrome 

* Cancer drugs can cause B9 deficiency 
* Vitamin B12 deficiency can lead to pernicious anemia (deficiency in production of red blood cells) 

impact of excessive B12 and B9 intake

\
* No significant effect associated with B12 
* Follic acid Can hide pernicious anemia

vitamin C (ascorbic acid - water soluble) food sources

fruits and vegetables 

purpose of vitamin C

holds cells together, forms bone and teeth, antioxidant, absorbs iron

therapeutic uses of vitamin c

prevention and treatment of scurvy, cancer prevention

effects of vitamin c deficiency

scurvy → weakness, bruising, anemia, loose teeth, bleeding gums

impact of excessive vitamin c

diarrhea, formation of kidney stones, rebound scurvy