Pharmacology Flashcards by Josh May

What is the clinical aim of pharmcokinetics?

To achieve effective drug concentration at site

of action long enough to produce a therapeutic action

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What is bioavailability?

The proportion of dose of a drug that reaches the site of action

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Where is the main site of drug absorption?

The small intestine

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What is the rate of absorption dependent on?

Gut motility

Splanchnic blood flow

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Give four characteristics of phase 1 of drug metabolism:

Transforms molecular structure of the drug (oxidation, hydrolysis, reduction etc)
Can Introduce polar group/Increase water solubility
Can abolish activity
Can produce toxic or non-toxic metabolites

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Describe the second phase of drug metabolism:

Transferases attatch an endogenous substance to parent drug or phase 1 metabolite
Increases polarity/water solubility so the metabolites can be eliminated

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What is the major route of drug excretion?

Renal

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What is clearance?

The virtual volume of blood cleared of drug per unit time

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What are receptors?

Proteins inserted into the membrane which bind neurotransmitters, hormones etc and produce a cellular response

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What are the four main types of receptors?

Ligand gated ion channels
G-protein coupled receptors
Kinase-linked receptors
Receptors linked to gene transcription

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What is affinity?

How well a drug binds to the receptor

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What is efficacy?

The measure of response produced by bound drug

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What is potency?

A combination of affinity and efficacy

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What is an agonist?

A substance which initiates a physiological response when combined with a receptor.

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What are clinical uses of partial agonists?

Reduce over-activity but do not block basal activity

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What are the three main neurophysiological changes resulting from anaesthesia?

Unconsciousness
Analgesia
Loss of reflexes

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What is the lipid theory of how anaesthetics work?

GA agents dissolve in membrane leading to:
changes in bilayer thickness
changes in order parameters
changes in curvature elasticity

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What are the two major problems with the lipid theory?

Stereoisomers

Cut off effect of carbon chain length

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What are the three main receptors implicated with the anaesthetic protein theory?

GABA receptor (inhibitory)
2 pore K+ channels (control resting potential)
NMDA receptor (excitatory)

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Greater solubility in blood of inhaled GA agents leads to what?

Slower rate of anaesthesia onset

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Give five characteristics of propofol:

Intravenous anaesthetic
Potentiates GABAA receptor responses
Rapidly metabolized in the liver.
Distributes in fatty tissues: high lipophilicity. 
Used as an induction agent.

Give four characteristics of thiopental:

Intravenous anaesthetic
Barbiturate used to induce anaesthesia.
Potentiates GABAA receptors
Highly lipid soluble

Why is halothane no longer widely used in clinical situations?

It’s associated with severe hepatotoxicity

Which inhaled GA agent is widely used in surgery?

Isoflurane

In which clinical situation is nitrous oxide generally used?

Obstetrics

What are the two pain pathways?

Peripheral nociceptive afferent neurons activated by noxious stimuli Central mechanisms by which the afferent input generates a pain sensation

What are the two types of pain?

``` Fast pain (Adelta fibres) Slower pain (C fibres) ```

Name two non-steroidal anti-inflammatory drugs:

Aspirin, ibuprofen

What is an opiate?

Drugs derived from the opium poppy

What is an opioid?

Opiates and synthetic opiate substances

What are the main CNS effects of Opioids?

Profound analgesia Respiratory depression Nausea and vomiting

Which are the endogenous ligands for opioid receptors?

Endorphins and enkephalins

What is the main opioid receptor antagonist?

Naloxone

What makes up the peripheral nervous system?

All nerves outside the brain and spinal cord

What are the five different steps of neurotransmitter release?

``` Synthesis Storage Release Activation Inactivation ```

Which neurones are noradrenaline released from and which is the exception from this?

``` Postganglionic neurone Sweat glands (release acetylcholine) ```

Which are the two classes of cholinoceptor that occur the PNS?

Nictotinic cholinoceptors | Muscarinic cholinoceptors

Which are the two classes of adrenoceptors that occur in the PNS?

Alpha-adrenoceptors | Beta-adrenoceptors

What type of receptors are nicotinic cholinoceptors?

Ligand-gated ion channels

What type of receptors are muscarinic cholinoceptors and all subtypes of adrenoceptors?

G-protein-coupled receptors

What does hemicholinium 3 do?

It competitively block the reuptake of choline

What does choline acetyltransferase do?

It synthesises ACh from precursors choline and acetyl coenzyme A

Which drug inhibits uptake and storage of synaptic vesicles?

Vesamicol

What does tetrodotoxin do?

It blocks voltage gated sodium channels

What do conatoxins do?

They block P/Q and N-type voltage gated calcium channels

What does botulinum toxin do?

It blocks vesicle fusion

What do dendrotoxins do?

They block voltage gated potassium channels (More calcium influx- more release)

What does ziconotide do, and where does it come from?

It acts as a selective N-type voltage-gated calcium channel blocker. It comes from cone snails

Which enzyme terminates activation of nicotinic ACh receptors at the NMJ?

Acetylcholinesterase

What is tubocurarine and what are its two clinical alternatives?

It's a competitive non-depolarising blocker. The alternatives that are actually clinically used are vecuronium and rocuronium

What does suxamethonium do?

It's a depolarising blocker which produces the rapid onset of paralysis