Review-Guide-in-Pharmacology-Prelim-Exam.pdf
Transcript
Review Guide in Pharmacology – Preliminary Exam Unit 1 – Fundamental Concepts in Pharmacology PHARMACOLOGY - is the study of drugs and its origin, chemical structure, preparation, administration, action, metabolism and excretion. PHARMACY – art of preparing, compounding, and dispensing dr...
Review Guide in Pharmacology – Preliminary Exam Unit 1 – Fundamental Concepts in Pharmacology PHARMACOLOGY - is the study of drugs and its origin, chemical structure, preparation, administration, action, metabolism and excretion. PHARMACY – art of preparing, compounding, and dispensing drugs. It also refers to the place where drugs are prepared and dispensed PHARMACEUTIC – first phase of drug when taken via the oral route, solid drugs will be converted to liquid form by gastric acids. PHARMACOKINETICS - study of the time course of drug absorption, distribution, metabolism, and excretion. How the body moves and affects the drugs. What the body do to the drug. PHARMACODYNAMICS - study of a drug's molecular, biochemical, and physiologic effects or actions. What the drug does to the body. DRUG NAMES 1.Generic or Nonproprietary Name - name approved by the Medical or Pharmaceutical Associations in the original country of manufacture and is adopted by all countries. e.g. Paracetamol 2. Brand name or trade name or proprietary name - name given by the manufacturer of the drug for selling in the market. e.g. Adol or Panadol or Biogesic 3. Chemical name - name that describes the atomic or chemical structure DRUG ACTIONS Stimulation effect is when the drug increases the rate of cell activity or secretion from the gland. Depression effect is when the drug decreases the rate of cell activity or secretion from the gland. Excipients - substances that will allow drug to take on particular size and shape and to enhance drug dissolution. Therapeutic effect - also referred as the DESIRED EFFECT (primary effect intended) Side effect - also referred as the SECONDARY EFFECT (unintended effect) – Hold the medications and inform the doctor. ADVERSE EFFECT (severe side effects) - Hold the medications and inform the doctor. Type A – Augmented – expected Type B – Bizarre – totally unexpected Drug Toxicity - Deleterious effects of a drug resulting from over dosage, ingestion of external use drug, and accumulation on the blood stream Drug Allergy - immunologic reaction to drug Drug Tolerance - exists in person with unusually minimal physiologic response to a drug compared to other individuals. A person was given a maximum dose of a drug but experienced low physiologic response/effect. Repeated administration of the same drug decreases the effectiveness of that drug – increasing the dose usually will be done PRINCIPLES OF DRUG ADMINISTRATION PRACTICE GUIDELINES ✓ If the RN is uncertain about the calculation, ask another nurse to double check ✓ What you prepare, you administer. Do not allow other nurse to give the medication that you prepared. ✓ Check Label of medication. ✓ Comparison of medication from written order to medication sheet. ✓ Recheck after preparation with another nurse. ✓ Correct Identification of patient – check ID band, ask the patient his name, compare in the patients chart and ID band. ✓ Observe 10 rights in giving medication – most important principle in drug administration. ✓ Right Medication – check at least 3 times ✓ Right dose – correct drug computation ✓ Right time - ✓ Right route- ✓ Right client - Asking patients name and compare it with ID band. ✓ Right client education - education about the medication and why it has been prescribed, evaluation of the patient’s response, laboratory monitoring of baseline values and possible side effects. ✓ Right documentation ✓ Right to refuse – nurse first action is to educate the patient on the importance of medication. ✓ Right assessment ✓ Right evaluation Principles of Drug Administration Safe drug administration 1. Oral Medications – most convenient route for drug administration, do not give to patient who are vomiting. Avoid crushing – sustained action drugs, enteric coated, buccal or sublingual tablets If the patient has difficulty swallowing an enteric coated tablet or capsule – advise the patient to take the medication with a large amount of water to facilitate swallowing. Give plenty of water to help swallow big enteric coated capsules or tablets. Parenteral medications – produces a more rapid response than oral medications. 2. If client has been prescribed with a new medication, the nurse should include in the health teachings a. Desired effect of the medication b. Dietary considerations c. Storage of medication in the refrigerator d. Written instructions on how to administer the medication OTIC MEDICATIONS Child – backwards and downwards Adult – backwards and upwards UNIT 2 – PHARMACOKINETICS PHARMACEUTIC – first phase of drug action for ORAL medications. Oral drugs will undergo this process before absorption. PHARMACOKINETICS – how the body moves and process the drugs First step - Drug Absorption – drug enters the bloodstream from its site of administration. Factors affecting drug absorption. Solid preparations are slower to absorb than liquid preparation, it needs to be dissolved first into a liquid form Drugs are readily absorbed in acidic than in alkaline environment. Drug solubility to cross membranes: when the drug is in stomach acid, it will pass through the stomach walls best if it is an acidic drug. Lipid soluble drugs are readily absorbed than Non-lipid soluble drugs – biggest factor determining the concentration of a drug that penetrates the brain. Elderly have less gastric acidity that might affect absorption (slower) Presence of food in the stomach do not always interfere with the absorption of a drug, some drugs absorbed faster with the presence of food, other drugs need to ingested in an empty stomach for faster absorption. Drug instability in gastric acid - factor associated with drug absorption that can result in incomplete absorption 2nd step - Drug Distribution – when drug is in the bloodstream 3rd step - Drug Metabolism (biotransformation)– liver – inactivate drug First Pass Metabolism – for oral meds – may decrease drug bioavailability. First Pass effect - The medication is extensively metabolized in the patient's liver when it passes through the intestine via the portal vein. 4th step - Drug Excretion - kidney EXCIPIENTS - Allow drug to take on particular size and shape and to enhance drug dissolution. DRUG HALF-LIFE is the time it takes for the amount of drug in the body to be reduced by half. It will help determine the frequency of drugs or dosing. For example: Ibuprofen 500 mg half - life is 2 hours. So after 2 hours 250 mg will be excreted out of the body and the other 250 mg still remains active inside the body. Depends on drug metabolism, concentration of drug in plasma and rate of drug elimination Half-life determines the dosage interval. UNIT 3 – PHARMACODYNAMICS It is the study of the effect of drugs on the body DRUG AFFINITY - how avidly a drug binds its receptor or how the chemical forces that cause a substance to bind its receptor. DRUG EFFICACY - refers to the drug's ability to activate the receptor once it has bound to it. Agonist – facilitate receptor activation Antagonist - prevent receptor activation MAXIMAL EFFICACY - the point at which increasing a drugs dosage no longer increases the desired therapeutic response. MAXIMUM EFFECTIVE CONCENTRATION - The concentration of drug in plasma that above these, toxic effects are precipitated. POTENCY – refers to the amount of drug needed to elicit a specific physiologic response or desired effect of a drug to produce a reaction. The maximal effect that a drug produces irrespective of concentration or dose. Both Drug A and Drug B achieve the same maximum effect, i.e. they have equal efficacy. However, drug A achieves this effect at a lower dose. Thus, Drug A has higher potency than Drug B. Drug A is more POTENT than Drug B Therapeutic Index - describes the relationship between the therapeutic dose of a drug (ED50) and the toxic dose of a drug (TD50). The higher the therapeutic index – the drug is moresafe to give. Drug with lower therapeutic window need to be monitored closely for adverse effects. Because the highest dose needed to produce a therapeutic effect is very close to the lethal or toxic dose. TI = TD50/ED50 Example: TD50 is 500 mg and ED50 is 250 mg = 500 / 250 = 2 If a drug Therapeutic index is small, the drug is a narrow therapeutic index drug. If a drug Therapeutic Index is big, the drug is a wide therapeutic index drug. PARAMETERS OF DRUG ACTIONS ONSET - Time from drug administration to first observable effect. The minimal effect of the drug is felt. Formula is T0 – T1 PEAK - occurs when it reaches its highest concentration in the blood/plasma concentration. We need to monitor our patient on the effectiveness of the drug by this time. And also the highest possibility of side effects will be seen. Formula is T0 – T2 DURATION OF ACTION - is the length of time the drug exerts a therapeutic effect. Formula is T1 – T3 Example: A drug is given at 8AM (T0) and give the minimum effect at 8:15 AM (T1), at 9AM (T2) the highest effectiveness of the drug was felt. At 10 AM (T3) the drug was no longer felt. Onset is 8am to 8:15 am = 15 minutes Peak is from 8am to 9am = 1 hour Duration of action is from 8:15 am to 10 am = 1 hour and 45 minutes DRUG RESPONSE Primary- always desirable/physiologic effects Secondary- desirable or undesirable Example: Diphenhydramine (Benadryl) Primary effect: antihistamine; treat symptoms of allergy Secondary: dizziness, sleepy, drowsiness DRUG-DRUG INTERACTION – highest priority related to taking more than one medication. Additive Effect- when two drugs given together have an effect equal to the sum of their respective effects. Synergistic- drugs may increase each other’s effect to an amount that is greater than the sum of their individual effects. It increases the effectiveness of the drug. Potentiation- the interaction of one drug increased by the presence of a second drug. Antagonistic- The combined effect of two drugs is less than the sum of their individual effects. It decreases the effectiveness of the drug. IDIOSYNCRATIC REACTION - Abnormal reactivity to the drug caused by a genetic difference between the patient and normal individual. For example one patient taking glutathione will result to healthy cells, whereas for patient with G6PD, glutathione will cause anemia. DRUG TOXICITY - The degree to which a drug can be poisonous and thus harmful to the human body. deleterious effects of drug over dosage or too much accumulation of drug on the blood stream. UNIT 4 : Pediatric calculations Drug calculation Formula Clark’s Rule: 𝑐ℎ𝑖𝑙𝑑𝑠 𝑑𝑜𝑠𝑒 = 𝑎𝑑𝑢𝑙𝑡 𝑑𝑜𝑠𝑒 × 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 𝑝𝑜𝑢𝑛𝑑𝑠 divided by 150 Weight is 7 kg , adult dose is 80 mg 7 kg = 15.4 pounds 80 mg x 15.4 pounds = 1232 1232 / 150 = 8.2 mg Young’s Rule: 𝑐ℎ𝑖𝑙𝑑 𝑑𝑜𝑠𝑒 = 𝑎𝑑𝑢𝑙𝑡 𝑑𝑜𝑠𝑒 × 𝑎𝑔𝑒 𝑖𝑛 𝑦𝑒𝑎𝑟𝑠 divided by 𝑎𝑔𝑒 𝑖𝑛 𝑦𝑒𝑎𝑟𝑠 + 12 The average adult dose of Amoxicillin is 500 mg every 8 hrs. The child weighs 26 lbs. and is 18 months old. 500 mg x 1,5 years / 1.5 years = + 12 750 / 13.5 = 55.55 56 mg = child dose Fried’s Rule: 𝑐ℎ𝑖𝑙𝑑 𝑑𝑜𝑠𝑒 = 𝑎𝑑𝑢𝑙𝑡 𝑑𝑜𝑠𝑒 × 𝑎𝑔𝑒 𝑖𝑛 𝑚𝑜𝑛𝑡ℎ𝑠 divided by 150 The doctor orders an adult dose of Ibuprofen 600 mg PO PRN. The child’s age is 24 months old. 600 mg x 24 / 150 96 mg UNIT 5 Autonomic Nervous System Agents Nervous System 1. Central Nervous System 2. Peripheral Nervous System A. Somatic Nervous System B. Autonomic Nervous System 1. Sympathetic 2. Parasympathetic - Agonist – stimulate sympathetic response - Antagonist – block sympathetic response - SYMPATHETIC NERVOUS SYSTEM – fight or flight Effects - heart rate, bp = increased, GI decreased, mydriasis - dilation of the pupils - Neurotransmitters – epinephrine, adrenaline - Receptors – alpha and beta receptors Alpha receptors – target – blood vessels Alpha 1 – stimulant Alpha 2 – control Beta receptors – target – 1 heart, 2 lungs - Alpha 1 receptor agonist– vasoconstriction - increase heart rate, contraction, mydriasis, increases blood pressure Examples: phenylephrine, epinephrine - Alpha 2 receptor agonist– vasodilation – decrease in bp - Example – Clonidine - Beta 1 receptor agonist– increased heart contractility and heart rate – (Presence of dysrhythmia – hold the ordered dose and inform the doctor) - Increased myocardial contractility - Beta 2 receptor agonist– bronchodilation Example : Albuterol – the nurse should monitor the patient for palpitations - Non- Selective Alpha Antagonist – blocks both A1 and A2 Example: Phentolamine - Alpha 1 Selective Antagonist – blocks only Alpha 1 causing vasodilation, decrease heart rate, contractility and bp. Example: Prazosin - Beta Blockers - Non Selective – blocks both B1 and B2 causing vasodilation decreasing bp but bronchoconstriction – don’t give to patient with asthma or respiratory problems. Example : Propranolol - Selective B1 antagonist/blocker – blocks only B1 causing vasodilation causing a decrease in BP but no bronchoconstriction. Example : Metoprolol – less likely to precipitate bronchoconstriction PARASYMPATHETIC NERVOUS SYSTEM – rest and digest Effects= heart rate, bp = decreased, GI increased, miosis - Parasympathomimetics - Cholinesterase inhibitors Neurotransmitters – Acetylcholine - cholinergic agonists – mimic Acetylcholine - Receptors – Nicotinic and Muscarinic Nicotinic receptors – target skeletal muscles Muscarinic receptors – target – smooth muscles, salivary glands, gastrointestinal stimulation - Muscarinic agonist – increase salivation, sweating, urination, gastric acid Example: Pilocarpine - Nicotinic receptor agonist – skeletal muscle contraction - Bethanechol – will cause miosis, diarrhea and bradycardia Nursing management - Perform urinary assessment - Excessive perspiration - clinical manifestation of extreme muscarinic stimulation - Succinylcholine as a neuromuscular relaxant - - Physostigmine – cholinesterase inhibitor - Side effects – bradycardia, hypotension, bronchospasm - Vasico selective – antimuscarinic agents causing bladder relaxation preventing urinary incontinence. Example: Oxybutynin – treatment for bladder incontinence – will cause decrease unrination - Atropine – muscarinic antagonists – decrease saliva, mucus secretions, prevent vomiting Antidote for excessive dosing of bethanechol - Atropine overdose – increase temp, confusion, flushed face, dryness of mouth, very thirsty - Neuromuscular blocking drugs = muscle relaxation - Parasympatholitics - Spasmolytics – nicotinic receptor antagonist Example - Dantrolene – skeletal muscle relaxation - Mydriatics – dilation of pupils - Vasico selective – antimuscarinic agents causing bladder relaxation preventing urinary incontinence. Example: Oxybutynin – treatment for bladder incontinence – will cause decrease unrination - Atropine – muscarinic antagonists – decrease saliva, mucus secretions, prevent vomiting Antidote for excessive dosing of bethanechol - Atropine overdose – increase temp, confusion, flushed face, dryness of mouth, very thirsty - Neuromuscular blocking drugs = muscle relaxation
