Foundations of medicine: Introduction to Pharmacology

  • Created by: Rachaelg
  • Created on: 15-10-20 19:02

What is clinical pharmacology

Clinical pharmacology teaches the mechanisms and effects (both beneficial and adverse) of drugs that doctors prescribe for their patients: why drugs work and how to prescribe them.

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Define the terms drug, medicine and placebo

A drug can be defined as a medicine or other substance which has a physiological effect when ingested or otherwise introduced into the body.

 A medicine can be defined as an active substance with a direct effect in the diagnosis, cure, mitigation, treatment or prevention of disease.

Meanwhile a placebo is an inactive substance administered as though it is a drug, but which has no therapeutic effect (other than pleasing the patient)

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Describe and explain the most important attributes

  • Efficacy- how effective is the drug at having the desired effect
  • Potency- how powerful is the drug, how much is needed to be perscribed to reach the desired effect
  • Safety- how many patients have unwanted side effects from the drug
  • Variability- what proportion of patients have the desired response when given the drug
  • selectivity- how selectivly does the drug act on its molecular target- does it effect other receptors
  • Bioavailability- how much of the drug is actually absorbed
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Define the terms Agonist and Antagonist

  • An agonist is a substance that is designed to revoke a response in the body.
  • An Antagonist reduces a response in the body
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Explain the term therapeutic index

The therapeutic index is a  measurement of the relative safety of a drug. It is a comparison of the amount of the drug that causes the therapeutic effect to the amount that is toxic. If a drug has a very high theraputic index it means that the effective theraputic dose will be very unlikley to cause toxic side effects.

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explain the term adherence

Adherance can be thourght of as the act of taking medication on schedule or taking medication as prescribed, to achieve the desired health benefit i.e. following a healthcare professional's advice.

factors effecting adherance can include:

  • Complexity of the regimen, which can lead to mistakes in doses, taking either too much or forgetting to take any
  • Failure of the patient to understand the importance of adherence, with treatments perceived as ineffective or unsafe
  • The patient's perception of barriers to adherence e.g. an unwillingness to make lifestyle changes to accommodate a recommended treatment regimen
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Explain the relationship between drug dose and res

In agonists as the drug dose increases the theraputic response increases,however once the drug has reached its maximum response the theraputic effect will stay the same as the dose is increased further. This is because all of the receptors available for the drug to act on will already be in use. 

Name the different aspects of the body that a drug

  • cell surface receptors
  • nuclear receptors 
  • ion channels
  • carrier proteins
  • intracellular or extracellular enzymes
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Explain Tachyphylaxis

Tachyphylaxis is the concept of short term tolerance. As a drug is repeatedly given, larger doses are needed to produce the same effect.

This can be due to receptor down regulation or due to enhanced drug elimination. When the same effect occurs over a long period of time it is simply known as tolerance. The effect is quite rare but most commonly occurs when perscribing opiods.

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