3&4 - Drug absorption Flashcards
Are strong or weak acids & bases better at being absorbed in the intestine
Weak - strong acids & bases are ionised at the pH of the intestine
Factors affection GI absorption of drugs (4)
GI motility
Splanchic blood flow
Particle size & formulation
Physiochemical factors
What causes gastric stasis and what does it do to absorption
Migraine, diabetic neuropathy
- decreased drug absorption
GI motility - Coeliac disease
Increased and decreased absorption of what drugs
Increased - thyroxine & digoxin
Decreased - propranolol, cotrimoxazol, cephalexin
GI motility - food _ drug absorption
Decreases
Metaclopramide affects _ receptors
Muscarinic
Example of a physiochemical factor - drug / drug interaction
Bile & warfarin
Compete for uptake transporters
Example of drug not absorbed
Mesalazine - for Crohn’s disease
1st pass metabolism - drugs excreted in faeces
Benzyl penicillin & insulin
Inactivated by gastric acid
1st pass metabolism - drugs metabolised a gut wall
Monoamines by MAO
Eg of 2 drugs with low hepatic extraction ratio
Paracetamol
Warfarin
Eg of 2 drugs with intermediate hepatic extraction ratio
Aspirin
Codeine
Eg of 2 drugs with high hepatic extraction ratio
Morphine
Propranolol
Route of cutaneous administration
Epidermis —> dermis —> hypodermis
Adv & disadv of cutaneous administration
Adv - skips 1st pass metabolism
Dis - variability in application of topically applied drugs
Eg of cutaneous drug
Nicorette - nicotine
What is a single bolus injection and example
Very high conc of drug
Infusion at a steady pace to avoid high plasma conc
Diazepam for epilepticus
Subcutaneous & intramuscular injections can be co-administered with _
Hyalouronidase
- digests intercellular matrix
- more rapid release of drug
What is intrathecal injection and example
Lumbar puncture needle
Local anaesthetics - bupivacaine
Symptoms of asthma
Inflammation
Mucus production
Bronchospasm
Treatments for asthma (3)
Adrenergic agonist (bronchodilators)
Glucocorticoids
Beta agonists (potent bronchodilators)
Corticosteroids in asthma
Decreases number of cells involved in inflammation (macrophages, eosinophils)
Problem with inhaled drugs
80-90% deposited in mouth and pharynx or swallowed
