Questions and Answers
What happens to glucuronides in the GI tract?
Tetracyclines should be avoided in pregnant people and young children because they have a high affinity for calcium.
True
What is the enzyme responsible for metabolizing ethanol?
alcohol dehydrogenase
Activated charcoal prevents aspirin overdose by decreasing aspirin absorption as it has ______________ that the drug molecules attach to.
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Which of the following is an example of a zero-order kinetics drug?
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Match the following drug transporters with their types:
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Thiopental is commonly used for anesthesia maintenance.
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What is the mechanism of action of ritonavir as a CYP inhibitor?
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What is the action of Salbutamol?
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Paracetamol is an analgesic that inhibits cyclooxygenase.
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What is the mechanism of action of Nifedipine?
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Fluoxetine is an antidepressant that works by ______________ serotonin re-uptake.
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Match the following antifungal drugs with their mechanism of action:
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What is the mechanism of action of Amphetamine?
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Teratogens are agents that cause birth defects.
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What is the mechanism of action of Chloramphenicol?
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Ritonavir is a potent ______________ inhibitor used to boost protease inhibitors.
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What is the mechanism of action of Morphine?
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Study Notes
Adrenergic receptors
- Adrenaline acts on β-adrenoceptors, increasing contractility
- α1, α2, and muscarinic acetylcholine receptors have different actions
- β-adrenoceptors activate adenylate cyclase
- Salbutamol is an agonist at β2-adrenoceptors, relieving bronchospasm
- Mechanism of salbutamol action: binds to β2-adrenoceptor, activates Gs protein, increases adenylate cyclase, and relaxing smooth muscle
Other receptors and drugs
- Acetylcholine acts on muscarinic receptors, stimulating nicotinic receptors
- Noradrenaline acts on α-adrenoceptors, mimicking endogenous ligands
- Phenylephrine activates α-adrenoceptors, causing vasoconstriction
- Diphenhydramine binds to histamine and muscarinic acetylcholine receptors
- Pancuronium is a nicotinic receptor antagonist, used for muscle paralysis
- Insulin activates insulin receptors, lowering blood glucose
- Prednisolone is a glucocorticoid drug, activating nuclear receptors
- Nifedipine blocks Ca2+ channels, treating hypertension
- Benzodiazepines enhance GABA-activated Cl- channel opening, treating anxiety
- Paracetamol inhibits cyclooxygenase, an analgesic
- Fluorouracil blocks DNA synthesis, an anti-cancer drug
- Ciclesonide is a prodrug, converted to an active metabolite in the lung
- Fluoxetine inhibits serotonin re-uptake, an antidepressant
- Amphetamine uses noradrenaline transporters, releasing neurotransmitters
- Ethanol increases drug metabolism, leading to lower plasma concentrations
Neurotransmitters
- GABA is an inhibitory transmitter, forming from glutamate
- Types: GABAa, GABAb (GPCR), GABAc (ion channel receptors)
- Glycine activates ion channel receptors, an inhibitory neurotransmitter
- Glutamate activates ion channel receptors, an excitatory neurotransmitter
- 5-HT activates ion channel receptors, increasing motility and vasodilation
- Suxamethonium is a long-acting agonist, causing neuromuscular block
Teratogens and adverse drug reactions
- Teratogens: agents causing birth defects by altering fetal growth
- Type A ADR: linked to pharmacological effects, showing a dose-response relationship
- Type B ADR: idiosyncratic, unpredictable adverse reactions
- Type D ADR: time-related, occurring after drug use
- Type F ADR: unexpected failure of drugs to produce therapeutic effects
- TOCP causes delayed neuropathy, a human teratogen
- Diethylstilbestrol is a synthetic estrogen, linked to severe birth defects
- Thalidomide causes severe birth defects, a human teratogen
- Fetal alcohol syndrome results from prenatal alcohol exposure
Antibiotics and antifungals
- Penicillin inhibits bacterial cell wall synthesis
- Amoxicillin is a broad-spectrum penicillin, not β-lactamase resistant
- Clavulanic acid is a β-lactamase inhibitor, semisynthetic
- Augmentin is a combination drug for penicillin resistance
- Cephalosporin inhibits bacterial cell wall synthesis
- Aminoglycosides inhibit bacterial protein synthesis, inhibiting initiation
- Tetracyclines inhibit bacterial protein synthesis, inhibiting tRNA binding
- Amphenicols inhibit bacterial protein synthesis, inhibiting transpeptidation
- Antifungal macrolides inhibit protein synthesis, preventing tRNA transfer
- Echinocandin inhibits fungal cell wall synthesis
- Polyenes alter fungal cell membrane integrity
- Allylamines alter fungal cell membrane integrity
- Azoles inhibit ergosterol biosynthesis, altering fungal cell membrane integrity
Enzymes and transporters
- CYP2D6 inhibitor: cimetidine
- Prodrug example: codeine -> morphine (dealkylation)
- Tenofovir disoproxil is a prodrug, hydrolyzed to tenofovir by esterase
- Morphine is metabolized to morphine-3-glucuronide (major) and morphine-6-glucuronide (minor) by UGT2B7
- Enterohepatic recirculation: lipophilic drug undergoes absorption, hepatic metabolism, conjugation, excretion into bile, and reabsorption
- Paracetamol is metabolized to NAPQI by GST
Important notes
- Charcoal prevents aspirin overdose by absorbing the drug, preventing reabsorption
- Sodium bicarbonate prevents salicylate overdose by alkalising urine, increasing ionization, and facilitating excretion
- Important ABC transporters: MDR1, MRP2, BCRP
- Important SLC transporters: OAT1, OAT3
- Ethanol is stored in total body water and metabolized by alcohol dehydrogenase
- Tetracyclines have high affinity for calcium and should be avoided in pregnancy and young children
- Thiopental is not used for anesthesia maintenance due to its lipophilic properties and potential for 'hangover' effect
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Description
This quiz covers the pharmacological actions of adrenaline, acetylcholine, noradrenaline, and phenylephrine on different receptors and their effects on various physiological processes.