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Questions and Answers
What is a potential consequence of drug withdrawal reactions?
At what stage of pregnancy is a fetus most vulnerable to teratogenic effects?
Which of the following correctly describes mutagenicity?
What is classified as an effect of carcinogenic agents?
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What characterizes drug intolerance?
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What is the significance of unintended drug effects in drug discovery?
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Which condition may result from excessive drug dosage?
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Which of the following statements about thalidomide is true?
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Which factor would most likely increase the elimination of a drug?
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What is the primary organ responsible for drug metabolism?
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Which of the following describes pharmacodynamics?
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How does malnutrition affect drug distribution in the body?
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What is the term for the desired intended effect produced from a drug administration?
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Which of the following is NOT a factor that affects drug absorption?
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What is a common side effect of the drug Promethazine?
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In which patient population is careful consideration of pharmacokinetics critical due to organ function impairment?
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Study Notes
Clinical Pharmacokinetics
- The study of drug movement within the body
- Includes Absorption, Distribution, Metabolism, and Elimination (ADME)
Absorption
- Factors influencing drug absorption:
- Drug Characteristics: Molecular weight, solubility, formulation
- Patient Factors: Route of administration, gastric pH, contents of the GI tract
Distribution
- Factors influencing drug distribution:
- Membrane Permeability: Drugs must cross cell membranes to reach their target.
- Plasma Protein Binding: Bound drugs cannot cross membranes.
- Malnutrition: Lower albumin levels in malnutrition lead to higher free drug concentrations, potentially increasing side effects.
Metabolism
- The body converts drugs into less active forms to facilitate elimination.
- Primary site of metabolism: Liver
- Liver can activate prodrugs (inactive forms) into their active form.
- Other sites of metabolism: Lungs
Elimination
- Routes of elimination:
- Pulmonary: Exhaled in the air
- Biliary: Excreted in feces (via the liver)
- Renal: Excreted by the kidneys
Special Patient Populations in Pharmacokinetics
- Renal disease: Impaired kidney function can affect drug elimination.
- Hepatic disease: Impaired liver function can affect drug metabolism.
Pharmacodynamics
- The study of drug action on the body.
- Includes:
- Mechanism of action: How drugs interact with receptors or other targets.
- Efficacy: How well a drug produces its desired effect.
- Safety and side effect profile: The potential risks and unwanted effects of a drug.
Pharmacodynamics: What the drug does to the body
- Cellular level: Effects on individual cells and their functions.
- General: Whole-body effects of the drug.
Therapeutic Effect
- The desired effect from drug administration.
- Examples:
- Blood pressure lowering
- Pain relief
- Blood glucose control
Side Effect/ Adverse Drug Reaction
- Unwanted but often unavoidable effects at therapeutic doses.
- Example: Promethazine (Phenergan), an anti-allergic drug, can cause sedation.
- Note: Adverse effects may be studied to develop new drug indications.
Drug Discovery Examples
- Minoxidil, initially used for hypertension, was found to cause hair growth and is now used for hair loss treatment.
- Sildenafil (Viagra), initially an antianginal drug, was found to improve erectile dysfunction and is now used for that purpose.
Toxic Effect
- Excessive pharmacological action due to overdose or prolonged use.
- Causes: Accidental, homicidal, or suicidal overdose.
Intolerance
- Characteristic toxic effects occur at therapeutic doses, indicating low individual tolerance to the drug.
Drug Withdrawal Reactions
- Abruptly stopping therapy can worsen the condition the drug was treating.
- Examples:
- Corticosteroid withdrawal can worsen immune status.
- Beta-blocker withdrawal can worsen angina.
Teratogenicity
- Capacity of a drug to cause foetal abnormalities when administered to a pregnant woman.
- Timing of exposure is critical:
- Fertilization and implantation (conception to 17 days): Often results in failure of pregnancy.
- Organogenesis (first trimester): Most vulnerable period for birth defects.
- Growth and development (second trimester): Developmental and functional abnormalities can occur.
Teratogenicity Examples
- Thalidomide: Associated with phocomelia (malformation of arms and legs).
- Anticancer drugs: Associated with cleft palate and hydrocephalus (large head).
Mutagenicity
- Capacity of a drug to cause genetic defects.
Carcinogenicity
- Capacity of a drug to promote the development of cancer.
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Description
This quiz covers the essential concepts of Clinical Pharmacokinetics, focusing on the processes of absorption, distribution, metabolism, and elimination of drugs. It explores factors influencing these processes, such as drug characteristics and patient factors, as well as the role of the liver in drug metabolism. Test your knowledge on how drugs move within the body!
