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Questions and Answers
What is the study of natural drug sources called?
Which term refers to the decreasing response to repetitive drug doses?
What is the best definition of pharmacodynamics?
Which of the following drug classes may not have similar chemical makeups but are used for similar effects?
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What is the official name of a drug that is used as its recognized designation in publications?
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What does pharmacodynamics primarily study?
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Which of the following accurately describes drug toxicity?
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Which factor is NOT typically considered in pharmacokinetics?
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What is meant by the term therapeutic index?
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Which of the following is an example of a side effect?
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Which action is primarily associated with β2-adrenoceptor activation?
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What is the primary clinical use of selective α2 agonists?
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What clinical condition is primarily treated with selective β2 agonists like salbutamol?
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What is a common side effect associated with adrenoceptor antagonists?
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Which of the following is a common side effect associated with non-selective β-adrenoceptor antagonists?
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Which of the following best describes the pharmacokinetic behavior of adrenoceptor drugs?
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What is the primary clinical use of selective α1 antagonists such as doxazosin?
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Which condition is treated with antiparasympathetic medications that affect gastrointestinal function?
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Which pharmacokinetic property can impact the bioavailability of some β-adrenoceptor antagonists?
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Which condition is most likely to require the use of phenoxybenzamine?
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Study Notes
Learning Objectives
- Define pharmacology, pharmacokinetics, and pharmacodynamics.
- Identify various routes of drug administration.
- Recognize factors affecting pharmacokinetics.
- Describe factors that influence drug dosing.
Historical Trends
- Evidence of medical practices dates back 5000 years with clay tablets containing prescriptions.
- Ancient beliefs attributed disease to evil spirits, evolving with Hippocrates’ notion of natural causes.
- Arab advancements in medicine and pharmacy are reflected in the establishment of hospitals and educational institutions.
- The 21st century prioritizes quality healthcare and nursing roles, including medication administration and patient education.
Terminology
- Pharmacology: Science that studies drug effects on the body.
- Pharmacopeias: Authoritative lists of approved drugs.
- Medication: Substance for diagnosis, cure, treatment, or prevention.
- Prescription: Instructions for drug preparation and administration.
- Therapeutic Effect: Primary intended effect of a drug (e.g. morphine as an analgesic).
- Side Effect: Unintended secondary effects, usually predictable.
- Drug Toxicity: Harmful effects resulting from overdose or misuse.
- Drug Allergy: Immunological reactions to a drug.
- Dose: Amount of drug that achieves desired effects with minimal harm.
- Therapeutic Index: Measurement of the safety of a drug; higher values indicate greater safety.
- Bioavailability: Extent and rate a drug reaches systemic circulation.
- Tolerance: Decreased response to repeated drug doses.
Basic Concepts of Pharmacology
- Pharmacokinetics: How the body handles a drug.
- Pharmacodynamics: Effects of the drug on the body.
- Pharmacotherapeutics: Clinical application of drugs.
- Pharmacognosy: Study of natural drug sources (plant and animal).
Drug Classifications
- Pharmacologic Classification: Groups based on similar characteristics or chemical make-up (e.g. Penicillins).
- Therapeutic Classification: Groups based on similar effects regardless of chemical structure (e.g. Antihypertensives).
Drug Sources
- Plants: Digitalis, vincristine.
- Human and Animal Sources: Epinephrine, insulin.
- Minerals: Iron, iodine, zinc.
- Synthetic Substances: Sodium bicarbonate.
Drug Therapy Across Lifespan
- Pregnancy: Must consider risks vs. benefits; drugs can affect fetal health; certain drugs are teratogenic.
- Breast Feeding: Drugs can enter breast milk; minimizing risk involves timing and drug selection.
- Geriatrics: Drug response variable; age influences absorption, distribution, metabolism, and excretion.
Routes of Administration
- Oral: Common, convenient, safe; disadvantages include ineffectiveness if vomiting occurs and drug absorption variability.
- Sublingual: Fast absorption; must remain under tongue until dissolved.
- Rectal: Useful for patients who cannot take oral medications due to taste.
- Subcutaneous (SC): Faster action; requires sterile technique.
- Intramuscular (IM): Rapid absorption and can administer larger volumes.
- Intravenous (IV): Direct access to bloodstream, allowing for immediate effects.
- Inhalation: Direct delivery to lungs.
- Topical: Application to skin or mucous membranes (includes transdermal patches).
Adrenoceptor Agonists
- Cause a decrease in blood pressure by inhibiting noradrenaline release and affecting the central nervous system.
- Selective B1 agonists, such as dobutamine, increase cardiac contractility but may induce cardiac dysrhythmias.
- Selective β2 agonists, like salbutamol, terbutaline, and salmeterol, primarily serve as bronchodilators for asthma management.
- Potential development of selective β3 agonists for obesity treatment.
Clinical Uses of Adrenoceptor Agonists
Cardiovascular System
- Adrenaline is used during cardiac arrest and anaphylaxis.
- Dobutamine (B1 agonist) treats cardiogenic shock.
Respiratory System
- Selective β2 agonists (e.g., salbutamol, terbutaline) are used for asthma.
- Xylometazoline and ephedrine are short-term nasal decongestants.
Other Uses
- Salbutamol can delay premature labor.
α-Adrenoceptor Antagonists
- Drugs like phenoxybenzamine and phentolamine were historically used for vasodilation in peripheral vascular disease but are now largely obsolete.
- Selective α1 antagonists (e.g., prazosin, doxazosin, terazosin) are utilized for treating hypertension, with side effects including postural hypotension and impotence.
- Tamsulosin selectively targets α1A receptors, mainly in the urogenital tract.
Clinical Uses of α-Adrenoceptor Antagonists
- Severe hypertension treated with α1-selective antagonists, often in combination with other drugs.
- Benign prostatic hypertrophy managed with tamsulosin.
- Phaeochromocytoma treatment with phenoxybenzamine as a pre-surgery preparation.
β-Adrenoceptor Antagonists
- Non-selective antagonists like propranolol affect both β1 and β2 receptors, while selective ones such as atenolol and nebivolol target β1.
- Partial agonist activity is found in alprenolol and oxprenolol, with clinical uses encompassing various conditions.
- Use in cardiovascular issues can lead to bronchoconstriction, bradycardia, and cardiac failure.
- Side effects include cold extremities, insomnia, depression, and fatigue.
Clinical Uses of β-Adrenoceptor Antagonists
- Indicated for angina pectoris, myocardial infarction, dysrhythmias, heart failure, and hypertension (not first choice anymore).
- Non-cardiovascular applications include glaucoma (e.g., Timolol eye drops) and treatment for thyrotoxicosis.
Gastrointestinal Uses
- Antispasmodic drugs like hyoscine assist with endoscopy and radiology.
- For peptic ulcer disease, gastric acid secretion is suppressed using M1-selective antagonist pirenzepine.
Cholinesterase and Anticholinesterase Drugs
- These drugs enhance cholinergic transmission at autonomic synapses and neuromuscular junctions.
- Neurological effects can occur with anticholinesterases that cross the blood-brain barrier (e.g., physostigmine).
- Symptoms of anticholinesterase poisoning include bradycardia, hypotension, excessive secretions, and muscle fasciculation.
Clinical Uses of Anticholinesterase Drugs
- Neostigmine or pyridostigmine treats myasthenia gravis.
- Alzheimer’s treatment includes donepezil.
- Glaucoma management can also involve anticholinesterase drugs.
Adrenoceptor Classification
- Two main α-adrenoceptor subtypes: α1 (vasoconstriction, gastrointestinal relaxation) and α2 (inhibition of transmitter release).
- Three β-adrenoceptor subtypes: β1 (cardiac effects), β2 (bronchodilation), and β3 (lipolysis).
- All receptors are part of the G-protein-coupled receptor superfamily.
Muscarinic Receptors
- M1 (neural) receptors stimulate ganglia, M2 (cardiac) receptors decrease rate and force of contractions, and M3 (glandular) receptors promote secretions and smooth muscle contraction.
Muscarinic Agonists
- Key compounds include acetylcholine and pilocarpine, primarily used for glaucoma and causing effects like bradycardia, vasodilation, and increased exocrine secretions.
Muscarinic Antagonists
- Major drugs include atropine and ipratropium, leading to dry secretions, increased heart rate, and smooth muscle relaxation.
Clinical Uses of Muscarinic Antagonists
- Atropine used for treating bradycardia post-myocardial infarction.
- Cyclopentolate for pupil dilation in ophthalmic procedures.
- Hyoscine prevents motion sickness.
- Antiparkinsonian effects for treating drug-induced movement disorders.
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Description
Test your knowledge on the fundamental concepts of pharmacology, including definitions of key terms such as pharmacokinetics and pharmacodynamics. Additionally, explore various routes of drug administration and factors influencing drug dosing. This quiz will help reinforce essential principles in the field of pharmacy.
