Module 5 - Non-Prescription Drugs PDF

# Module 5 - Non-Prescription Drugs ## Section 01 - Over-the-Counter Drugs * **Prescription Drugs** - drugs restricted to sale by prescription only. * **Non-prescription Drugs** - drugs that can be sold to the general public without a prescription. * Includes over-the-counter drugs. * The...

# Module 5 - Non-Prescription Drugs ## Section 01 - Over-the-Counter Drugs * **Prescription Drugs** - drugs restricted to sale by prescription only. * **Non-prescription Drugs** - drugs that can be sold to the general public without a prescription. * Includes over-the-counter drugs. * These drugs are sold 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 OTC Drugs 1. These drugs are not a replacement for prescription drugs or care by a professional, and should only be used in certain circumstances: * The symptoms should be mild. * Serious ones should be treated by a physician. If they become worse, consult one. * If adverse effects occur, stop taking the drug immediately. * It is important to recognize that the use of OTC products can have serious consequences. * OTC products are still drugs, meaning they can cause toxicities on their own, as well as cause drug interactions with other drugs. * If in doubt, consult a local pharmacist. * Self-medication should not exceed 2 weeks without consulting a physician. ### Safety and Efficacy of OTC Drugs * The sale of OTCs are controlled by a section of the Food and Drugs Act. * This controls the safety, efficacy, advertising, and sale of these products. * All new OTCs are subjected to rigorous preclinical testing for safety. * Post-market safety surveillance is also conducted on all OTCs. * Some prescription drugs become OTCs. * Extensive clinical trials are conducted before this happens. ### Selection of Appropriate OTC Drugs * The best OTC drug for a known condition will prove efficacy for the condition and have a known level of toxicity. * The best OTC drug will have the simplest formulation (single ingredient). * In most cases, formulations that contain multiple drugs have one drug that is effective and others of questionable efficacy. * The best is not necessarily the brand name product. * Generics are usually cheaper than the name brand and are just as effective. * The best will come in the appropriate dosage form. * It will have a therapeutic effective dose of the active ingredient. * A number of OTCs contain too low a dose to be effective. ## Common OTC Drugs ### Internal Analgesics * **Analgesics** provide relief from pain. * **Acetylsalicylic acid** (generic name for Aspirin): * Effectively relieves pain, fever, and inflammation. * It inhibits the synthesis of prostaglandins. * Endogenous substances that enhance the mediation of pain + fever, and have a role in inflammation. * Low doses of ASA have been shown to prevent stroke and heart attack. * Inhibits platelet aggression and hence clot formation. * Have a number of adverse effects: * Gastric irritation * The most common toxicity * ASA breaks down the mucosal protective barrier in the stomach, which leads to irritation and increased bleeding. * Becomes a problem when it is taken chronically at high doses. * This problem is tried to be fixed by adding an antacid, but it is generally more effective to use an analgesic and antacid as separate entities. * **Acetaminophen (Tylenol)**: * Most widely used OTC analgesic. * Causes inhibition of prostaglandin synthases, which are the enzymes responsible for the formation of prostaglandins. * Is an effective analgesic and antipyretic (equally to ASA). * Available in liquid preparation and thus is convenient and suitable for children/infants. * Chosen over ASA because it does not cause gastric irritation or fever. * All therapeutic doses it is very well tolerated. * However, acetaminophen overdose can lead to fatal liver injury. * Have to take ~20 tablets * Individuals with alcohol use disorder or liver disease are more susceptible. * In some cases, liver injury can occur at large therapeutic doses if taken for a long time. * An issue is that it is found in multiple products. * So an individual may unknowingly overdose. * **NSAIDS (Ibuprofen (Advil) and naproxen (Aleve))**: * Another class of internal analgesics are the non-steroidal anti-inflammatory drugs. * Effective analgesic, antipyretic, and anti-inflammatory compounds. * Among the most effective OTC anti-inflammatory agents available. * Adverse effects include: gastric irritation (less than ASA), skin rash, dizziness, blurred vision, and fluid retention. * **Mechanism of action**: * Tissue damage causes arachidonic acid to be released. * It is then converted to enzymes to either protective or inflammatory prostaglandins. * COX-1 converts it to protective ones, while COX-2 converts it to inflammatory ones. * Internal analgesics act by blocking the conversion of arachidonic acid. * Blocking Cox-2 is beneficial, but blocking Cox-1 leads to adverse effects. * **All of these drugs don't block these drugs the same way.** * **Most of these drugs are internal, but topical products are also available.** * Ex: topical diclofenac ### Antihistamines * Used to treat allergy symptoms. * Act by blocking histamine receptors. * The main substance released in allergies. * Prevents the binding of histamine and therefore decreases allergy symptoms. * Classified as first and second generation agents due to slight differences in pharmacology. * First gens all cause sedation and drowsiness. * Second gens are less sedating and thus the preferred agents. ### Drugs for Excess Stomach Acid * Are designed to either neutralize stomach acid or decrease its secretion. * **Antacids**: * Objective is to hold the pH of gastric contents at about 4. * Neutralize gastric acid by acid-base chemical reactions. * **Systemic** - given orally and well absorbed by the GI tract: * Ex: Calcium carbonate (Tums) * **Non-systemic** - also taken orally but are not absorbed. * Ex: Aluminum hydroxide * Coats the mucosal lining of the stomach, protecting it from the acid. * One of the more popular antacids as it has a fast onset. * **H₂ Receptor Antagonists**: * But it may decrease phosphate absorption, the absorption of other prescription drugs, and cause constipation. * Stomach acid secretion involves the transfer of H+ into the stomach in exchange for K+ (active process). * Histamine (distinct from those that cause allergies) are involved in the release of acid. * When H₂ receptors are activated the proton pump is turned on and acid secretion increases. * The H₂ receptor antagonists block the receptors, thus reducing acid secretion. * These are more effective than antacids. * Free of major adverse effects. * Though skin rashes, headaches, and confusion may occur infrequently. * **Proton Pump Inhibitors (PPIs)**: * Permanently bind to the protein pump, inhibiting acid secretion by at least 90%. * The most effective. * Low frequency of adverse effects (diarrhea, headaches, confusion). * Just recently became OTCs after being prescription drugs. ### Decongestants * Congestion is caused by the dilation of small blood vessels, allowing fluid to leak from them into the spaces between cells. * Decongestants cause constriction of these blood vessels. * Nose drops containing 0.5% phenylephrine or an oral tablet of pseudophedrine are the drugs of choice. * Long term use leads to local irritation and chronic congestion. * So use should not exceed 3 days. * Other adverse effects include, rebound congestion and potential blood pressure alterations. ### Cough Suppressants * In general, a productive cough should not be suppressed, but a non-productive cough should be. * **Centrally-Acting Cough Suppressants** * Block the processing of information in the brain, which reduces the frequency of the cough. * Codeine is present in some of these: * Ex: dextromethorphan hydrobromide * Effective dose = 20-30 mg every 6 hours. * **Peripheral Cough Suppressants** * Block the nerve endings in the throat and bronchioles, inhibiting the stimulus to cough. * Efficacy is questionable. * Placebo is most likely the reason for any efficacy observed. ### Sleep Aids * Are intended to help an individual fall asleep or to relieve sleepiness. * Ex: Melatonin * Hormone that plays a key role in the body's internal sleep-wake cycle. * Night time OTCs add first gen antihistamines in an attempt to produce sedating effects. ### Laxatives * Increase excretion of soft-formed stool by increasing gut motility or the hydration of the stool. * **Stimulant Laxatives**: * Increase motor activity of the intestine and increase secretion of mucus, water, and electrolytes into the intestine. * Adverse effects include: cramping, water/electrolyte disturbances, and functional disturbances in the GI tract (following long-term use). * **Bulk-Forming and Osmotic Laxatives**: * They swell in water to form a gel-like solution that keeps stool soft. * May also indirectly stimulate peristalsis. * Osmotic laxatives draw water into the stool, making it softer. * Full effect occurs 2-3 days after use began. * These are the preferred therapy in most cases. * Also cause water/electrolyte imbalances. ### Antidiarrheal Agents * Used to control diarrhea. * Should not be used if diarrhea is accompanied by a fever >38.5 °C or if there is blood or mucus in the stool. * See physician. * **Absorbents**: * Add bulk to the GI tract and may absorb toxins. * Useful for dealing with short-term, self-resolving diarrhea. * Ex: Pepto-Bismol * **Loperamide**: * Synthetic opioid that doesn't penetrate the CNS but inhibits gut motility by binding to opioid receptors in the GI tract. * Effective for mild/moderate diarrhea. * The drug of choice. * **Hydrocortisone Cream**: * Topical anti-inflammatory agent used to treat exposure to poison ivy, insect bites, etc. * 0.5% or 1%. * More effective than calamine lotion. * **Sunscreens**: * Use is recommended to everyone older than 6 months, everyday when going outside. * Reduces risk of common skin cancers by 40-50%. * **Chemical Sunscreens**: * Contain compounds that absorb UV radiation before it can penetrate the skin. * **Physical Sunscreens**: * Contain minerals that block and scatter UV rays before they can enter the lower layers of the skin. ### OTC Drug Interactions * ASAs can cause bleeding when given with oral anticoagulants (ie. blood thinners). * Antacids can interfere with the absorption of some drugs because they change the pH of the stomach acid and coat the stomach lining. ## Section 02 - Herbal Drugs * **Herbal drugs** - plants or parts of plants that are used to prevent or treat illness, or improve health. * Approximately 80% of people worldwide have used them. * Gaining popularity in Canada. * Due to the desire of the general public to use natural products, because they believe they are safer. * Though natural chemicals can still be toxic. * Manufacturers and retailers are also promoting their use for financial gain. * Many of today's drugs are still derived from natural sources. ### Classifications of Medical/Herbal Products * **Allopathic Medicine** * Refers to drugs used by mainstream medicine. * They have Drug Identification Number (DIN) from Health Canada, and have undergone extensive testing for safety and efficacy. * **Herbal Medicine** * Plant products being sold to treat a condition and do not have a DIN. * Are often unpurified and often lack phase 3 clinical trial data. * **Phytopharmaceuticals**: * Drugs obtained from plants which are purified and used at therapeutic doses with scientific evidence of efficacy and documented toxicity. * **Allopathic Phytopharmaceuticals**: * Drugs obtained and purified from plants that meet all the requirements of a drug. * And therefore have full status as a drug. ### Value of Plants for Pharmaceuticals * They have a number of uses in the preparation of both herbal and allopathic drugs. * A direct source of some therapeutic agents. * Provide a source of raw materials for the manufacturing of modified semi-synthetic compounds with modified properties (ie. efficacy). ### Problems Associated with Herbals * Lack of safety and efficacy data. * Very few have actually undergone randomized control trials. * New regulations were put in place in 2004 for better regulations of these products. * Interpreting the literature. * The literature aimed at the general public tends to overstate the efficacy of herbal preparations. * The Natural Medicines Comprehensive Database is the recognized go-to resource for evidence based information on herbal medicines. * Rates their effectiveness on a scale. * Lack of standardization across similar herbal products. * Intentional adulteration. * The addition of substances other than the herbal even in herbals marketed as pure substances. * Differing global standards. * Drug interactions with allopathic medications. * Therefore it is important to inform physicians of the use of any herbal medicine. ### Overview of Herbal Drugs (examples) * **St. John’s Wort** * According to the NMCD, it is likely effective for mild to moderate depression. * Herbalists recommend it for mild to moderate depression and healing wounds. * Active ingredients include *hypercin* and *hyperforin* which have true antidepressant properties. * Less effective than other antidepressants but superior to a placebo. * Toxicities include: * A syndrome that manifests as confusion, agitation, shivering, fever, sweating, diarrhea, muscle spasms, and tremors. * Phototoxicity (sunlight causes rashes/a reaction). * Therapeutic Uses: * Prevention and treatment of scurvy. * No real benefit in taking it for a cold (unless under special circumstances). * May be useful in combination with other proven anticancer drugs due to antioxidant activities. * **Deficiency**: * Can result in scurvy. * Symptoms include: weakness, bruising, anemia, loose teeth, and bleeding gums. * **Excessive Intake**: * Can result in diarrhea, formation of kidney stones, and rebound scurvy. ## Section 04 - Food Additives **Food Additives** - substances added to food to improve its appearance, texture, and storage. * May include added during the processing of food or added to improve nutritive value. ### Classes of Food Additives * **Intentional**: * Substances added to food to improve appearance, texture, and storage of food. * Ex: vitamins, minerals, flavors, colors, preservatives, and texture agents. * **Unintentional**: * Added inadvertently as a result of growing, manufacturing, and storage processes of food. * Are often termed as *contaminants*. * Amount present in foods is limited by regulations. * Ex: fertilizers, pesticides, heavy metals, and biohazardous contamination. ### Food Additive Regulations in Canada * Conducted by the Food and Drug Regulations under the authority of Health Canada. * All permitted additives and their conditions of use are listed in the *List of Permitted Food Additives*. * If an additive is not on the list, the manufacturer is required to submit information on the proposed use, evidence of safety, and information on its efficacy. * Submission is then evaluated by Health Canada. ### Determining Toxicity of a Food Additive * Efficacy is easily determined, but a number of problems arise when trying to determine toxicity. * The current technique is to determine the risk/benefit ratio. * To study the toxicity in animals and then extrapolate the results to humans. * Though the animals are only given the additives for a couple of years, whereas humans can be exposed their entire lives. * So risk estimates must be based on a lifetime of exposure. * The highest no-effect dose in animals is calculated and the acceptable human dose is either 1/100 or 1/1000 of that. * Assumption is made that studying high doses in animals mimics low-dose lifetime exposure in humans. * This tends to overestimate the actual risk. ### Food Additives as Carcinogens * Additives are carefully tested for carcinogenicity. * If a positive response is observed, the compound is usually not allowed to be a food additive. ### Rational Use of Food Additives * Use of additives is justified if they enhance or maintain the quality or acceptability of food. * They should only be used in quantities sufficient to obtain intended purpose. * They should be pure. * Toxicological evaluations should be undertaken. * Information should be collected and used to determine their potential risks and whether or not further study is needed. * Special groups should be considered: * Ex: heavy drinkers and cobalt chloride * Cobalt chloride was added to beer to control the amount of foam. * At toxic doses, it causes inhibition of heart muscle function. * 24 beers would need to be consumed everyday for long periods of time to receive this toxic dose. * Unfortunately, a number of heavy drinkers in the 1960s would die from this. * Thus, it is no longer added to beer. ### Current Concerns with Food Additives * People mistrust them. * Natural additives can also be harmful (carcinogenic). * Not allowed to be added but still naturally exist. * They may cause hyperactivity in some children. * Ie. food colours and some preservatives. ### Classes of Food Additives * **Flavouring**: * Quite prevalent in foods. * Thousands of flavouring agents are in use, thus testing has not been as thorough as other additives (approved due to experience obtained over years of use). * Though cases of toxicity issues are quite rare. * Includes: flavouring agents and enhancers, essence of smoke, synthetic flavours, and stimulated flavours (mixture of artificial flavours). * The flavour enhancer *MSG* has shown to cause tightening of muscles in the face and neck, headache, nausea, and giddiness. * Some are more sensitive to this than others. * **Colours**: * Organic dyestuffs added to give food an appetizing appearance. * Most are well evaluated. * Some allergic reactions have occurred to food colours. * The most common being to *tartrazine* (a yellow food colour). * Individuals allergic to aspirin may also be allergic to this. * Canada only allows 10 food colours to be used. * It has banned *Red Dye No. 2* as it produces cancers when given in high doses in animal studies. * **Texture Agents**: * Added to improve or give a specific texture to a product. * Found in foods in relatively high concentration (up to 1-3% of the product). * They possess little to no toxicities. * *Silicates* - added to flour and flour products to keep them free flowing. * *Emulsifying/Thickening Agents* - added to a number of frozen foods (ie. ice cream/sherbet). * **Preservatives**: * Preserve the quality of food. * One of the more rational uses of additives. * Allows for the delivery of food to distant destinations and ensures the appropriate quality of the food. * The benefits outweigh the risks in most cases. * **Antibacterials**: * Can also be used to add flavour. * Smoke - age-old method in preserving food (mainly meats). * Though there are concerns that natural smoke carries a small carcinogenic risk. * Some current products have had their carcinogens removed. * **Antibiotics**: * The most effective antibacterial additive. * However, they are banned in Canada to prevent the emergence of antibiotic resistance. * **Sodium Nitrate**: * Added to meats to give a pleasing red colour and prevents growth of a specific bacteria. * Use of nitrates is controversial, and is being attempted to be reduced. * Is known to cause the formation of *nitrosamines*, which are carcinogenic. * **Antioxidants**: * Prevent the oxidation and thus the rancidity + discolouration of foods. * Improve the storage and quality of the product. * **Water-soluble**: * Added to reduce the oxidation of carbohydrates (ie. the browning of fruits). * Ascorbic and citric acids are commonly used agents. * **Fat-soluble**: * Added to prevent fats from becoming rancid/oxidizing. * Used in potato chips, cookies, cakes, etc. * Some have been shown to cause liver damage. * Should not be taken with other antidepressants. * As it increases the risk of adverse effects. * Products containing both this and *ephedra* should be avoided due to additive CNS excitation. ### Aloe Vera * NMCD says it's possibly effective for cold sores and minor skin irritations. * Herbalists recommend it to be applied topically as an aid to heal wounds and burns. * Active ingredients are *mannans* and *anthraquinones*. * Alt. ingredient by increasing the microcirculation of the skin. * Upon ingestion, it causes severe diarrhea. ### Devil's Claw * NMCD says it's possibly effective for osteoarthritis and back pain. * Insufficient evidence for any other suggested indications. * Herbalists recommend it for things like migraines to kidney disease. * Though it's most commonly used to treat inflammatory conditions, the active ingredients are believed to be *iridoid glycosides*, which may have some anti-inflammatory properties, but studies suggest they are inactivated by stomach acid. * Most common toxicity is diarrhea ### Panax Ginseng * Possibly effective for thinking, memory, erectile dysfunction, multiple-sclerosis related fatigue, sexual arousal, and reducing the risk of developing influenza. * Said to enhance memory, learning, productivity, and the immune system. * Claimed to reduce blood sugar in diabetics. * Proper RCTs are lacking. * Toxicities include: headaches, high blood pressure, and bleeding. * It can also increase insulin levels in the blood. ### Echinacea * Possibly effective for the common cold. * Insufficient evidence for all other indications. * Herbalists recommend it for the prevention of the common cold, wound healing, and as an anti-inflammatory agent. * A number of studies have found that *echinacea* extracts can stimulate T-lymphocytes (cells involved in immunity). * Toxicities are rare. * Allergies are possible. * Those with autoimmune diseases should not take it. ### Valerian * Possibly effective for mild insomnia. * Herbalists recommend it for treating anxiety and panic attacks. * Liver toxicity may be a significant problem. * CNS depressive properties may impair an individual's ability to operate a car. ### Sweeteners * Vitamin may be used for this. * Less effective but also less toxic. * Sugar is the most common. * **Saccharin**: * Was the first artificial sweetener developed. * Use was restricted in Canada because of studies that have demonstrated it to be a potential cause of cancer. * Restrictions were removed in 2016 after a detailed safety assessment. * **Aspartame**: * Has largely replaced saccharin. * Has been reclassified as a potential carcinogen by WHO due to a possible link to liver cancer. * WHO set a safety threshold of 40 mg per kg of body weight per day. * Most diet pops contain 200-300 mg. * Individuals with *phenylketonuria* cannot handle *phenylalanine* (an amino acid in aspartame). ==End of OCR==