Week 2 notes.docx - Week 2 Chapter 2 Review of basic principles of pharmacology Pharmacodynamics Study of effects of drugs on the body Drugs effect on

Week 2 notes.docx - Week 2 Chapter 2 Review of basic...

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Week 2 Chapter 2 – Review of basic principles of pharmacology Pharmacodynamics Study of effects of drugs on the body. Drugs effect on receptor site at cellular level. Drug-Receptor interaction Receptor + drug = action - measure in serum levels. Drug-receptor activity Lock and key concept – Agonist + receptor = pharmacological response Antagonist = receptor = no pharmacological response (blockers) Higher dose=max effect at receptor site Natural agonists receptor subtypes: histamine: H1, H2 and catecholamine: alpha1, alpha2, beta1, beta2. Interact with receptors to regulate the functioning of the body. If continually stimulated, responsiveness may be decreased – down-regulation or desensitization. If severe, refractoriness or lack of response to the drug. If chronically reduced by antagonists – up-regulation or hypersensitization . If rapidly withdrawn, strong reaction resulting in exaggerated supersensitive receptors. Ie – w/d of antiHTN results in hypertensive episodes. Reversible agonist – drug discontinued, no drug effects at receptor sites Irreversible – drug occupies receptor permanently Antagonist – binding of drug and antagonist is reversible Competitive antagonist- effect of antagonist can be overcome by the higher doses of the agonist competing for the receptor site. Noncompetitive inhibitor - receptor is irreversibly blocked by the antagonist, cannot be overwhelmed by the agonist. Partial agonist – Drug agonists competes with full agonists for drug receptors, results in decrease of effect on receptor over agonist alone. Drugs are agonists, partial agonists, or antagonistic Drug-receptor binding is usually reversible Drug-receptor binding is selective – very specific!!! Drug-receptor binding is graded – the more receptors filled, the greater the response Therapeutic index Relationship between desired therapeutic effect and its adverse effects is therapeutic index. Ratio of dose required to produce death or serious toxicity in 50% of subjects compared with doses required for effective treatment of 50% of subjects – if difference is wide, drug is safe. If difference is narrow, close monitoring required (Vancomycin). Dose-response relationship Onset, peak, elimination IV or IM – eliminates or shorten absorption time (quicker onset of action). Example – Benadryl PO versus IV/IM.
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Drug potency and efficacy Efficacy – measured by the maximum effect the drug can achieve Potency is a relative measure that compares the doses of two different drugs that are required to achieve the same effect. (high intrinsic activity at lower doses) Influenced by absorption, distribution, metabolism, and excretion. ** When deciding which of the two drugs to prescribe, consider the relative maximum effectiveness rather than the relative potency ** Pharmacokinetics Study and analysis of the time course of the drug in the body.
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  • Winter '16
  • Pharmacology, Receptor antagonist, Drug – drug

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