Module 5 - Non-prescription drugs Flashcards
2 categories of drugs
- prescription drugs
- non prescription drugs
OTC drugs
Over the counter drugs
sold without a prescription based on the premise that the general public is able to diagnose mild symptoms and to select appropriate agents to treat these symptoms
Guidelines for using an OTC drugs
- OTC drugs are not a replacement for prescription drugs or care by a healthcare professional, and should only be used in certain circumstances
- illness and or symptoms:
- the illness of symptoms are mild
- serious illness or symptoms should be treated by a physician
- if the illness or symptoms become worse, consult a physician
Adverse effects of OTC
- if adverse effects occur, stop taking the drug
- the use of OTC products can have serious consequences
- OTC products can cause toxicities on their own as well as cause drug interactions with other drugs, including herbal and prescription drugs
Safety and efficacy of OTC drugs
sale of OTC drugs is controlled by a section of the food and drugs act
all OTC products are subjected to rigorous preclinical testing for safety
post-market safety surveillance is also conducted on all OTC products
not all OTC products have been subjected to randomized controlled trials
- instead, they are available because they have been on the market and have been used for decades
- this is known as grand-parenting: a process where new regulations do not apply to those products already on the market
concerns with the lack of randomized control trials:
- some of the older OTC drugs may not be effective
- the only appropriate manner for assessing the efficacy of any drug is a randomized control trial
- for some older OTC drugs may have serious toxicities
Selection of appropriate OTC drugs
- proven efficacy and known toxicity
- simple formulation and ingredients
- brand vs generic
- appropriate and effective dose
Common OTC drugs
- internal analgesics
- antihistamines
- drugs for excess stomach acid
- decongestants
- cough suppressants
- sleeping aids
- laxatives
- antidiarrheals
- hydrocortisone cream
- suncream
Internal analgesics
provide pain relief
3 common OTC analgesics:
1. acetylasalicylic (aspirin)
2. Acetaminsophen (tylenol)
3. NSAIDS (advil and aleve)
acetylasalicylic (aspirin)
relieves pain, fever, inflammation by inhibiting the synthesis or prostaglandins
in low doses, it prevents stroke and heart attack by inhibiting clot formation
Adverse effects:
1. gastric irritation
2. tinnitus
3. Reyes syndrome
4. allergic reaction
Acetaminophen (Tylenol)
Mechanism of action: inhibition of prostaglandin synthetase which is the enzymes responsible for the formation of prostaglandins
Therapeutic use: effective analgesic and antipyretic but not an effective anti-inflammatory
Adverse effects:
- overdose can lead to fatal liver injury
- individuals with alcohol use disorder and liver disease are more susceptible to the liver toxicity
NSAIDs (advil and aleve)
internal analgesics are non-steroidal and anti-inflammatory drugs
Therapeutic use: effective analgesics, antipyretic, and anti-inflammatory compounds
Adverse effects:
- gastric irritation
- skin rash
- dizziness
- blurred vision
- fluid retention
Mechanism of action of internal analgesics
- when tissue damage occurs, arachidonic acid is released
- arachidonic acid can be converted by the enzyme COX-1 into prostaglandins which are involved in many beneficial effects such as gastroprotection, platelet aggregation, renal protection, vasodilation, and bronchodilation
- arachidonic acid can also be by the enzyme converted into COX-2 into inflammatory prostaglandins causing detrimental effects such as inflammation, pain, fever, and decreased platelet aggregation
- analgesics work by blocking one or both of the enzymes, decreasing the production of prostaglandins involved in inflammation, pain, fever, but also decreasing the production of the protective prostaglandins
Internal vs topical analgesics
most pain is best treated with an internal analgesic, but some topical products are available for the relief of pain associated with minor sprains and joint pain
Antihistamines
- used in the treatment of all allergy symptoms such as hay fever
- these drugs act by blocking histamine receptors, thereby inhibiting the binding of histamine to its receptor, decreasing allergy symptoms
First and second generation antihistamines
- antihistamines are classified into first and second-generation agents due to slight differences in their pharmacology
- the first generation causes sedation and drowsiness
- diphenhydramine
- the second generation is less sedating and is the preferred agents
- cetirizine
- the first generation causes sedation and drowsiness
Drugs for excess stomach acid
designed to either neutralize stomach acid or decrease stomach acid secretion
three main classes of drugs for excess stomach acid:
1. antacids
2. h2 inhibitors
3. Proton pump inhibitors (PPIs)
Antacids
- neutralize the acid in the stomach
- objective is to hold the pH of gastric contents at about 4 by an acid-based chemical reaction
- systemic:
- given orally and are absorbed by the GI tract
- example: tums (calcium carbonate)
- non-systemic:
- also given orally but not absorbed and thus do not cause systemic alkalosis
h2 inhibitors
- target acid secretion in the stomach
- transfer of protons (H+) into the stomach in exchange for potassium (K+), histamine is involved in the release of stomach acid
- without H2 receptor antagonist
- when the histamine receptors in the acid-secreting cells of the stomach are activated, the proton pump is turned on and acid secretion is increased
- with H2 receptors
- these drugs are free from major adverse effects, although skin rashes, headache, and confusion are infrequently reported
PPIs
- target acid secretion in the stomach
- example: omeprazole
- permanently bind to the proton pump, inhibiting acid secretion by 90% or more
- they are the most effective drugs available for suppressing acid secretion
- the frequency of adverse effects is low and includes diarrhea, headache, and abdominal pain
- these drugs were only available by prescription until recently
Decongestants
- congestion is caused by the dilation of small blood vessels, which allows fluid to leak from the vessels into the spaces between cells
- decongestants cause constriction of blood vessels, preventing the accumulation of fluid and thereby reducing congestion
Long term use of decongestants
leads to local irritation and chronic rhinitis (long-lasting congestion)
Cough suppressants
centrally acting cough suppressants:
- block the processing of information in the brain, reducing the frequency of the cough
- codeine is present in some OTC cough suppressants since they suppress the cough centre
- an alternative OTC cough suppressant is dextromethorphan hydrobromide
peripheral cough suppressants:
- block the nerve endings in the throat and bronchioles, inhibiting the stimulus to cough
- in these agents, camphor and menthol are added to vaporizers or rubbed on the throat and chest
- the efficacy of these products is questionable
Sleep aids
Intended to help an individual fall asleep or to relieve sleeplessness
- example: melatonin
many nighttime preparations of OTC drugs also exist (Nyquill, Aleve PM)
Laxatives
increase excretion of a soft-formed stool by increasing the motility of hydration of the stool
stimulant laxatives:
- increase the motor activity of the intestine and increase secretion of mucus, water, and electrolytes into the intestine
- adverse effects of stimulant laxatives include cramping, water, and electrolyte disturbances, and functional disturbances in the GI tract following long-term use
Bulk-forming and osmotic laxatives:
- swell in water to form an emollient gel or viscous solution that maintains soft stool
- these indigestible bulk substances may also indirectly stimulate peristalsis
- osmotic laxatives draw water into the stool, resulting in softer stool
- full effect of both occur in 2-3 days after therapy has begun
- these are preferred laxatives for most indications
- adverse effects of these laxatives include water and electrolyte disturbances, making adequate hydration essential
Antidiarrheal agents
- used to control diarrhea
- the major concern with diarrhea is dehydration, especially in young children and elderly
absorbents:
- add bulk to the GI tract and may absorb toxins
- they are useful to control the acute symptoms of self-limiting diarrhea (will resolve on its own)
loperamide:
- a synthetic opioid that does not penetrate into the CNS
- it inhibits gut motility by acting on opioid receptors in the GI tract, reducing peristaltic activity
- it is effective for mild to moderate non-infectious travellers’ diarrhea (no fever of blood in stool), as it inhibits cramps
Hydrocortisone cream
topical anti-inflammatory agent used for exposure to poison ivy, poison oak, poison sumac, insect bites, and any inflammatory condition that is treated topically
Sunscreens
- chemical:
- contain compounds that absorb UV rays before they can penetrate into your skin, such as avobenzone and octisalate
- physical:
- sunscreen contains minerals, such as titanium dioxide and zinc oxide, that block and scatter UV rays before they can enter the lower layers of the skin
SPF
how many times longer you can be in the sun without burning when using sunscreen as indicated compared to unprotected skin
Other drug interactions with OTC preparations
ASA and antacids are also known to interact with other medications
ASA = may produce bleeding
Antacids = interfere with the absorption of some drugs
Herbal drugs
refer to plants or plant parts that are used to prevent to treat illness, or improve health
Classification of medicinal/herbal products
- allopathic medicine - drugs used by mainstream medicine, have a DNI
- herbal medicine - plant products sold to treat the condition and don’t have a DNI (drug identification #)
- phytopharmaceuticals - refer to drugs obtained from plants which are purified and used at therapeutic doses with scientific evidence of efficacy and documented toxicity
- allopathic phytopharmaceuticals - refer to drugs obtained and purified from plants that meet all the requirements of a drug and therefore have full status as a drug
Problems associated with herbals
- lack of randomized control trials
- interpreting literature
- lack of standardization
- intentional adulteration
- differing global standards
- drug interactions with allopathic medicine
6 common herbal drugs
- st johns wort - treating wounds and is a antidepressant for mild moderate
- aloe vera - possibly treats sunburns and wounds and cold sores, causes severe diarrhea
- devils claw - possibly treats osteoarthritis and back pain
- Panax ginseng - possibly treats thinking and memory, erectile dysfunction, multiple sclerosis-related fatigues, sexual arousal, and reducing the risk of developing influenza
- echinacea - possibly treats common cold, wound healig=ng, and anti-inflammatory agent
- valerian - possibly treats insomnia, anxiety, panic attacks
Improving herbal products
- appropriate standards for content and purity of the purported active ingredients need to be ensured
- the efficacy of these products needs to be determined in randomized controlled trials
- valid toxicity testing needs to be completed
- herbal products that do not possess some pharmacological activity need to be compared to the current array of allopathic compounds available to treat those conditions
Classification of vitamins
2 main categories:
- water-soluble: vitamin C and 11 vitamins in the B group
- fat-soluble: vitamins A, D, E, K
Are vitamins drugs?
when a person obtains vitamins from a healthy diet, the vitamins in the food are not considered drugs
however, when vitamins are consumed as a tablet in a chemically pure form, they are considered drugs
What warrants the use of vitamins and supplements?
- need for increased nutrition
- absorption distrubances
- inadequate nutritional intake
Approaches to vitamin therapy
- nutritional approach
- individuals select a diet aimed at supplying the recommended dietary allowance (RDA) for each vitamin or a multivitamin preparation that supplies the RDA of each vitamin - megavitamin approach:
- individual ingest vitamins in excess of the RDA
Vitamin A
fat soluble
found only in animal products, such as liver, milk, fat, and egg yolk
required for growth and development, for the normal structure of the mucous membranes and epithelial, and as a constituent of a complex molecule in the rods of the eye, called rhodopsin, which is required for night vision
Use and effects of vitamin A
therapeutic uses:
- vitamin A is administered in periods of increased requirement, such as infancy, pregnancy, and lactation
- vitamin A derivatives are used in the treatment of acne and some other skin disease including psoriasis and skin cancers
deficiency:
- can result in a delay of growth and development, night blindness, and drying of the surface of the eye, changes in the cell lining the bronchioles in the lung which enhances the opportunity for respiratory infection, and dry, thick, and horny skin
excessive intake:
- excessive vitamin A intake can result in dry itchy skin, vomiting, headache, and enlarged liver and spleen
retinoids
vitamin A derivatives, associated with a number of adverse effects
Vitamin D
fat soluble
vitamin D is found in meat, fish and mushrooms
Vitamin D increases the absorption of calcium and phosphate from the intestine, which is needed for new bone formation
it is also involved in the regulation of blood calcium levels and in the removal of calcium from older bone
Use and effects of vitamin D
therapeutic use:
- prevention of osteoporosis
deficiency:
- can result in decreased absorption of calcium and phosphate from the intestine, and therefore a decreased blood calcium level
- deficiency can also lead to the removal of calcium from bone in an attempt to maintain blood calcium levels
- as a result, defective bone growth occurs in infants and children leading to bow-leggedness or rickets
excessive intake:
- can result in elevated calcium levels in the blood
- calcium is deposited in several tissues, including the kidney, heart, lungs, blood vessels, and skin
- during pregnancy, the fetus also suffers from high blood calcium level
- this is concerning for individuals with kidney or heart disease
Vitamin E
group of fat-soluble compounds
vitamin e is used to describe a number of naturally occurring tocopherols that are present in vegetable oils and some leafy vegetables
essential for a number of biochemical reactions, including a role as an antioxidant and protecting cells in the cardiovascular system and other tissues from the damaging of free radicals
Use and effects of vitamin E
therapeutic use:
- has been found to be useful in the treatment of premature babies with an uncommon type of hemolytic anemia (red blood cells are destroyed faster than the body can make them)
- this effect may be due to the antioxidant effect of vitamin e
deficiency:
- rare, as the tocopherols are so prevalent in our diets
- it may occur in the condition of a malabsorption syndrome (Crohns disease)
excessive intake:
- can inhibit platelet aggregation and contribute to the anticoagulant effect or warfarin
Vitamin b12 and folic acid
vitamin b12 also known as cobalamin is water soluble vitamin
folate (naturally occurring) or folic acid (synthetic) is vitamin B9 and is found in many foods
vitamin b12 is found in meats and dairy products
all food groups are rich in folate, however, fresh green vegetables, liver, and yeast are especially high in folate
function: work together in the synthesis of red blood cells
Use and effect of vitamin B12 and folic acids
therapeutic use:
- absorption of vitamin B12 decreases with age, as a result some elderly individuals may need to increase vitamin B12 intake
- the RDA for folic acid increases in pregnant women to help prevent deficiences that may lead to neural tube defects in the unborn child
deficiency:
- alcohol misuse or malabsorption syndrome can lead to deficiences in both vitamin b12 and folate
- if vitamin B12 cannot be absorbed from the intestines, a condition known as pernicious anemia can occur
- certain drugs may result in folate deficiency
- oral contraceptives, folate antagonists in chemo, etc
excessive intake:
- to date, no significant toxic effects have been associated with vitamin b12
- folic acid is generally considered non-toxic when taken as a supplement, however, it can mask undiagnosed pernicious anemia and is now used in chemo
Vitamin C
also called ascorbic acid, is water soluble
fruits and vegetables
contributes to the framework that holds cells together, is required for the formation of bone and teeth, functions as an antioxidant, and helps absorb iron
Use and effects of vitamin C
therapeutic use:
- prevention of scurvy
- a number of studies have suggested that under one special circumstance (a very fit person working in extremely hard or under hostile conditions) supplementation with vitamin C may be beneficial
- it has been claimed that the antioxidant activity of vitamin C may be of use in preventing cancers
- in combination with other proven anticancer drugs
deficiency:
- can result in scurvy
- weakness, bruising, anemia, loose teeth, and bleeding gums
excessive intake:
- can result in diarrhea, formation of kidney stones, and rebound scurvy
What are food additives
- substances that are added to food to improve the appearance, texture, and storage of food
- this may also include substances added during the processing of food or added to improve the nutritive value
2 classes of food additives:
- intentional - substances added to food to improve appearance, texture, and storage of food
- unintentional - added inadvertently as a result of the growing, manufacturing, and storage processes of food (contaminants)
Determining toxicity of additives
the risk/benefit ratio of additives must be carefully determined (the technique is to study the toxicity in animals and then extrapolate the result to humans)
exposure:
- the extent of exposure in humans is difficult to replicate in animals
- additives are administered to animals of one or two years, while humans can be exposed in their entire lives
- risk estimates must be made on a lifetime of exposure
assumption of risk:
- additives are usually testing in animals and the highest no-effect dose is calculated
- the acceptable human dose is then taken as 1/100 or 1/1000 of the maximum no-effect dose in animals
- the assumption made is that studying high doses in animals will mimic low-dose lifetime exposure in humans
- the human exposure is based on estimates of the intake of that particular food
- the assumptions tend to overestimate the actual risk
Rational use for food additives
- function - maintain the quality of food
- quantity - sufficient to obtain the stated ends
- purity - should be pure
- toxicological evaluation - should be undertaken
- special groups - need to be considered (cobalt chloride and alcoholics)
Current concerns with food additives
some food additives are not regulated due to a loop hole:
- some additives are privately tested and deemed generally recognized as safe outside the FDA
- they won’t state on the label what they may do to your body
- therefore, if you want to know what you are ingesting, you have to do the research
Classes of food additives
- flavouring
- colours
- texture agents
- preservatives
- sweetners
Flavouring
includes substances such as flavouring agents and enhancers, the essence of smoke, and synthetic flavours
4-5 thousand flavourings are in use and most have not been adequately tested, but are approved due to the experience obtained over years of use
studies have shown that very few flavourings have demonstrated toxicities
Colours
organic dyestuffs added to give food an appetizing appearance
most are well evaluated
Texture agents
texture agents are added to improve or impart a specific texture to a product
these substances are found in foods in relatively high concentrations of up to 1-3% of the product
- as a class, these agents possess little or no toxicity
silicates:
- added to flour and flour products to keep them free-flowing
emulsifying/thickening:
- added to a number of frozen foods
Preservatives
the use of agents to preserve the quality of food is one of the more rational uses of additives
it allows for the delivery of food to distant destinations and ensures the appropriate quality of the food for the consumer
in most cases, the benefits outweigh the risks
2 types:
1. antibacterials: smoke, antibiotics, and sodium nitrite
2. antioxidants: water-soluble and lipid-soluble
Sweetners
Saccharin:
- use of saccharin was restricted in Canada based on studies that demonstrated a potential for it to cause cancer
- however, in 2016 health Canada food directorate completed a detailed safety assessment on saccharin and removed the restriction, allowing it to be tabletop sweeteners
Aspartame:
- saccharin has been largely replaced by aspartame
- the only toxicity of note associated with aspartame is that individuals with a condition known as phenylketonuria cannot tolerate phenylalanine, one of the amino acids in aspartame
