Background PK/PD Flashcards
Why do older adults generally have less total body water than younger adults?
a. As functional cells die during the aging process, less water is needed.
b. The muscle mass of older adults is smaller than the muscle mass of younger adults.
c. Older adults have a smaller extracellular fluid to intracellular fluid ratio than younger adults.
d. The plasma volume of older adults is decreased to reduce the risk for excess fluid volume and heart failure.
Muscle cells are a large portion of the body and contain more water than many other types of cells. As a person ages, the size of muscle cells tends to decrease and the volume of total body water decreases in proportion to this loss of muscle cell mass.
Which adverse drug events in the elderly can be attributed to pharmacodynamic causes?
a. Constipation/confusion due to diphenhydramine and paroxetine.
b. Respiratory depression due to benzodiazepines.
c. AKI due to combination of ACE-I and NSAIDs.
Paroxetine class and indication
Class: Selective serotonin reuptake inhibitor (SSRI).
Treatment of
- Major depressive episode.
- Obsessive Compulsive Disorder (OCD).
- Panic disorder with and without agoraphobia.
- Social anxiety disorders/social phobia.
Diphenhydramine class and indication
Class: ethanolamine-derivative H1 receptor antihistamine. It is an antihistamine with anticholinergic.
Cough and colds: cough suppressant formulation
Seasonal allergies: in nasal decongestant formulation
Define frailty clinically
Frailty is described as a ‘reduced ability to withstand illness without loss of function’
What are the two changes in drug absorption seen with the elderly populations?
Changes to active transport. Thus reduced absorption of Vitamin B12, iron and calcium through active transport.
Reduced dopa decarboxylase in gastric mucosa. Increased Levodopa absorption.
How is first pass metabolism altered in the elderly population. And what are the potential effects?
Reduced liver mass and blood flow. Therefore increased bioavailability of the drugs with first pass metabolism and reduced activation of pro-drugs in the liver.
Name a drug that undergoes extensive first pass. Name is MAO, Class and indication.
Propranolol (highly lipophilic) non selective beta adrenergic receptor blocker. Used: Therapy of hypertension, cardiac arrhythmias, angina pectoris and hyperthyroidism
Labetalol: nonselective antagonist at beta-adrenoceptors and a competitive antagonist of postsynaptic alpha 1-adrenoceptors.
Name a prodrug and what is is converted to.
Give its MAO and indication
Enalapril is ACE-I used in management of hypertension and congestive heart failure. It is hydrolysed to release the active converting enzyme inhibitor enalaprilat.
How is drug distribution affected in the elderly population?
Relative reduction in total body water results in reduced volume distribution and increase serum concentration of water-soluble drugs.
Relative increase in adipose tissue. Therefore increased volume distribution and longer half life of lipid soluble drugs.
Name water soluble drug.
MAO and indication
Gentamicin is hydrophilic drug log S -1.6. It an aminoglycoside.
Digoxin Class 5 antiarrhythmic drugs( cardiac glycoside).
Name drug that is highly lipophilic
MAO and indication
Diazepam has log P 3.08 and it is a benzodiazepine.
How is drug clearance altered in elderly population ?
Reduction in glomerular filter action rate.
Reduction in liver mass and blood flow.
Name the classes of drugs that is cleared renally?
Water-soluble antibiotics
Diuretics
Digoxin
Lithium
Name a couple of drugs the have high hepatic extraction ratio
Clomethiazole
Glyceryl trinity ate
Propranolol
Draw the flowchart summarising the possible mechanism by which water homeostasis alteration can affect muscle function and promote frailty?
Drug A is weakly basic drug with a pKa of 7.8. If administered orally, at which of the following sites of absorption will the drug be able to readily pass through the membrane?
A. Mouth (pH 7.0)
B. Stomach (pH 2.5)
C. Duodenum (pH 6.1)
D. Jejunum (pH 8.0)
E. Ileum (pH 7.0)
D
NN610 is an investigational cholesterol-lowering agent. NN610 has a high molecular weight and is extensively bound to albumin. NN610 will have a _______ apparent volume of distribution (Vd)?
A. High
B. Low
C. Extremely high
D. Normal
B
Equation for Vd
Where F is the bioavailability: AUC IV/ AUC Drug from route administration.
Cp: peak plasma concentration.
Progonosis of CKD by GFR and albuminuria Categories