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Introduction to Pharmacology… Learning Objectives Define the terms Pharmacology, Pharmacokinetics, Pharmacodynamics. List the various routes of administration of drugs. List factor effect on pharmacokinetics. Describe some factors that dedicate of the dose. Historical Trends Since the beginning people search to treat illness and cure disease the oldest known prescription found on a clay( 5000 years ago). Primitive people through the Egyptian period believe that evil spirit living in the body. Hipocrates ( fifth century) advanced idea that disease resulted from natural causes. The arabs’ interest of in medicine, pharmacy and chimistry was reflected in hospitals and schools. Historical Trends Historical Trends In twenty first century, the emphasis on providing quality health care. Nursing role which include administering medication in health care agency, community and home care setting, teaching client safe and effective self administration to better care for their clients. Terminology Pharmacology: is a science that studies the effect of the drugs on the body. Pharmacopeias: are the total of all authorized drugs available within the country. Medication: is a substance administered for diagnosis, cure, treatment, mitigation or prevention. Prescription: the written direction for the preparation and the administration of the drug. Terminology Cont ….. The therapeutic effect: is the primary effect intended that is the reason the drug is prescribed such as morphine sulfate is analgesia. Side effect: secondary effect of the drug is one that unintended, side effects are usually predictable and may be either harmless Terminology Cont ….. Drug toxicity: harmful effect of the drug on an organism or tissue, result from overdose or external use. Drug allergy: is immunological reaction to a drug. Terminology Cont ….. Drug interaction: occur when administration of one drug before or after alter effect of one or both drug. Drug misuse: Is the improper use of common medications in way that lead to acute and chronic toxicity for example laxative, antacid and vitamins. Terminology Cont ….. Drug abuse: is an inappropriate intake of substance either continually or periodically. Drug dependence: is a persons reliance on or need to take drug or substance there are two type of dependence: Terminology Cont ….. Physiological dependence: is due to biochemical changes in the body tissue these tissue come to require substance for normal function. Psychological dependence: is emotional reliance on a drug to maintain a since of wellbeing accompanied feeling of need. Terminology Cont ….. Drug habituation: denotes a mild form of psychological dependence. Illicit drug: also called street drug are those sold illegally. Terminology Cont ….. Dose :The aim to give patient a dose of the drug that achieves the desired effect with out causing with harmful side effect. Therapeutic index: is a measure of the danger of poisoning and the higher it is safer of drug is. Aspirin (3.5), digoxin (2) Terminology Cont ….. Bioavailability: Means that the drug has reached the circulation and is therefore available for all the tissues. (ex: aspirin 600 mg). Tolerance: A decreasing response to repetitive drug doses basic concepts of Pharmacology Pharmacokinetics: is a bout how the body deal with drug. Pharmacodynamics: is effect of drug on the body. Pharmacotherapeutics: is a clinical using of drug. Pharmacognosy: The study of natural (plant and animal) drug sources. Branches of Pharmacology Pharmacognosy - Origin Pharmacokinetics - Movement through Body Pharmacodynamics - Effect Pharmacotherapeutics - Use/Purpose Toxicology -Side Effects Pharmacokinetics Science Pharmacognosy Toxicology of Pharmacology Pharmacodynamics Pharmacotherapeutics The generic name: is given for the drug to being official name. The official name: is the name under which its listed in one in the official publication. The chemical name: is the name by which the chemist knows it. The trade mark or brand name (proprietary name) : is name given by the drug manufacture Example: hydrochlorothiazide (official name). Esidrex (brand name) Examples Chemical Name 7-chloro-1,3-dihydro1-methyl-5 phenyl 2H-1, 4-benzodiazepin 2-one Ethyl 1-methyl 4pheyli-sonipecotate hydrochloride Generic Name diazepam Trade Name meperidine Demerol acetylsalicyclic aspirin Valium Ecotrin Source of drugs 1. Plants: such as digitalis, vincristine. 2. Human and animals: such as epinphrine, insulin and adrenocoticotrpoic hormone. 3. Minirals: as iron, iodine and zinc 4. Synthetic and chemical substance: as sodium bicarbonate Drug Classifications Pharmacologic Classification Similar Characteristics Similar Chemical Make up examples: Penicillins, Beta Blockers Therapeutic Classification Used for similar effect May not have similar chemical make up Examples: Antihypertensives, Antibiotics Drug action across lifespan Drug administration during pregnancy Drug administration during childhood Drug administration during adulthood Drug therapy during Pregnancy and BreastFeeding Must balance risks vs benefits of drugs during pregnancy – Affect fetus more than mother? – Teratogenic effects – Mother’s health affects fetus— Chronic asthma is more dangerous to the fetus than the drugs used for treatment (mother’s who do not take medication for asthma the incidence of stillbirths is doubled!!) Drug therapy during Pregnancy and BreastFeeding Pregnancy alters drug disposition and excretion processes By 3rd trimester renal blood flow is doubled with an increase in glomerular filtration and elimination of drugs increases(therefore will need an increased dosage of drug to compensate) Tone and motility of intestines (peristalsis) decrease in pregnancy(more time for drugs to be absorbed) Drug therapy during Pregnancy and BreastFeeding All drugs can cross the placenta Lipid soluble cross more easily Ionized, highly polar or protein bounds cross with difficulty Nicotine (smaller babies) Alcohol (dependence) Cocaine/heroine/morphine (addictive to fetus) Bacterial and viral infections Teratogenesis The process by which congenital malformations are produced in an embryo or fetus. Cleft palate Hydrocephalus Spina bifida Behavioral and biochemical anomalies Teratogenesis 3 stages of embryonic development Pre-implantation (conception to week 20) Embryogenic period (week 3 to week 8) Fetal period (week 9 to term) – During pre-implantation and embryonic stages the teratogen acts in an all-or-none response, i.e. , is dose is high enough the fetus will die, if dose is sub-lethal fetus will recover – Gross malformations produced by exposure to teratogens during the embryonic period (1st trimester) – Exposure during the 2nd and 3rd trimesters usually results in organ dysfunction rather than gross malformations Few drugs considered to be teratogenic: hard to prove – Incidence of congenital anomalies is low – Animal test may not be applicable – Prolonged exposure may be necessary – Teratogenic effects may be delayed – Behavioral effects are hard to document – Controlled experiments cannot be done in humans • To prove a drug is a teratogen: – Drug must cause a characteristic set of malformations – It must act only during a specific window of vulnerability (weeks 4 through 7 of gestation) – Incidence of malformations should increase with increasing dosage and duration of exposure • Risk of malformation with most teratogens is only ~10% Drug Therapy during Breast Feeding Drugs get through breast milk and can affect infant Lipid soluble drugs are in higher concentration Things That Can Minimize Risk: – Dose after breast feeding – Take drugs with short ½ life – Take drugs that are not found in breast milk – Avoid drugs known to be hazardous Drug Therapy in Pediatric Patients Patients who are young or old respond differently to drugs than do middle aged people Pediatrics- all patients under age 16 Pre-mature infants (< 36 weeks gestation) Full-term infants (36-40 weeks gestational age) Neonates (1st 4 weeks post-natal) Infants (5-32 weeks postnatal) Children (1-12 years) Adolescents (12-16 years) Very Young Patients – At risk for prolonged and intense responses Response of Infants due to differences in: • Drug absorption- absorption of drugs IM is greater in infants than neonates and adults • Renal drug excretion (reduced in infants) • Hepatic drug metabolism (low in new born) • Protein binding of drugs (albumin lower in infants) • Exclusion of drugs from CNS by blood-brain barrier (not sully developed in infancy making infant much more susceptible to drugs) – By one year- pharmacokinetic response similar to adult Drug Therapy in Geriatric Patients Elderly more sensitive to drugs and exhibit more variability in response Altered pharmacokinetics (organ degeneration) Multiple and severe illnesses Multiple drug therapy and usage Poor compliance “Individualization of treatment is essential: each patient must be monitored for desired responses and adverse responses, and the regime must be adjusted accordingly” Geriatric patients will vary quite a lot from one patient to another Physically fit patients respond differently than out of shape Absorption- percentage of absorption DOES NOT usually change with age, but rate may be slowed (drug response may be delayed) Gastric acidity may be increased in aged affecting absorption of certain drugs Distribution- in aged there is: Increased body fat- reduces plasma levels of lipid soluble drugs Decreased total body water- increases concentration of water soluble drugs and intensity of response Reduced concentration of serum albumin- malnourishment decreases albumin and results in increased drug levels Metabolism: hepatic functions decrease in elderly and drug levels increase (amount of dysfunction variable) Excretion: decline of renal function in elderly (variable) therefore increase drug levels in plasma Determine renal function by creatinine clearance rates Pharmacodynamic Changes: alterations in receptor levels may change on a number of cells. Decreased affinity of receptors Route of administration: 1. Oral is the most common Advantage: Least expensive and most convenient route for most clients. Safe, does not break the skin. Concoius, able to swallow. Oral medication Oral Route Disadvantage: Inappropriate for client nausea and vomiting. Drug may have unpleasant taste. May cause irritation of gastro intestinal tract. Drug may discolor teeth. Drug can be aspirated by ill client. Sublingual A drug placed under the tongue, where it dissolved. Advantage: Same as oral plus Drug may administered for local effect. Drug rapidly absorbed into blood stream. More potent than oral. Disadvantage: If swallowed drug may be inactive. Drug must remain under the tongue until dissolved. 3. Baccal: pertaining to the cheeks. 4 . Rectal: can be used when drug objectionable taste. 5. Translingual: on the tongue. 5. Subcutaneous (SC): hypodermic into subcutaneous tissue, just below the skin. Advantage: onset drug action faster than oral. Disadvantage: SC 1. 2. 3. 4. 5. Must involve sterile technique because breaks skin barrier. More expensive than oral. Can administer only small doses. Slower than intramuscular injection. Some drug can irritate tissue and can cause pain. 6.Intramuscular (IM): into in the muscle. Advantage: Pain from irritating drugs is minimized. Can administer large volume of drug. Drug rapidly absorbed. Disadvantage: breaks skin barrier. Can be anxiety producing. 7. Intradermal (ID): is the administrating of a drug into the dermal layer of the skin just beneath the epidermis, usually small amount of liquid is used for example 0.1ml. Advantage: absorption is slow (this advantage test for allergy). Disadvantage: amount of drug administered must be small. Breaks skin barrier 8. Intravenous (IV): allow injection of drugs and another substance directly into bloodstream through the vein. 9. Inhalation: is apply to drugs directly onto lungs. 10. Topical Route 1. Skin (including transdermal patches) 4. Eyes Ears Nose 5. Lungs (inhalation) 2. 3. Question?
