Pharmacology Flashcards by Emilia Summers

What is pharmacodynamics?

Drug action on the body

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What is pharmacokinetcs?

Body action on a drug

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What does an agonist do?

Gains a response

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What does an antagonist do?

Blocks a response

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2 steps of receptor activation?

Affinity (binding to receptor)
Efficacy (change from bound and inactive to active)

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Do agonists vs antagonist possess affinity and efficacy?

Agonists possess both
Antagonists only possess affinity

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Affinity is determined by?

Binding and dissociation rates

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A high affinity ligand will have a ….. binding rate compared to …. ?

High and low dissociation rate

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Efficacy is determined by?

Forward beta activation rate vs backwards alpha inactivation rate

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A ligand with high efficacy will have a … beta rate and … alpha rate?

High and low

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An antagonist can be + an agonist can be?

Competitive or non-competitive + only competitive

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Competitive antagonists + agonists bind to what?

Both to the active site/ orthosteric site

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Non-competitive antagonists bind to what?

Allosteric site

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2 shapes of agonist depending on graph + 2 key values?

Hyperbolic curve on a linear graph or sigmoidal on a log graph
EMAX is the highest level of response
EC50 is half the maximal response

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What are full agonists?

Can reach their EMAX

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What is a partial agonist?

Cannot reach EMAX

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Agonist + competitive antagonist effect on curve?

Shift to right as more agonist needed to reach EMAX

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Agonist + non-competitive antagonist effect on curve?

No shift but depression of curve as EMAX/EC50 cannot be reached

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Autocrine signalling?

Cell signal acts on itself

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Paracrine signalling?

Cell signal acts on neighbour cells

Endocrine signalling?

Cell signal moves via blood to target areas of the body

4 main types of cell receptors?

Ligand-gated, GPCRs, kinase-linked and nuclear (all in the cell membrane except nuclear)

Ligand gated channel rate of action?

Fast action

GPCR rate of action + structure?

Act slowly
NH2 + COOH ends with 7 transmembrane domains
Alpha, beta and gamma subunit
Alpha subunit has a guanine nucleotide bonding site

GPCR signalling summary?

- GTP binds to guanine binding site on alpha unit - Alpha unit dissociates from beta and gamma subunit to modify G-protein - Signal turned off when GTP is hydrolysed

2 main types of GPCR alpha subunits and their actions?

- Gs via sympathetic innervation stimulates adenyl cyclase/ cAMP formation - Gi via parasympathetic innervation inhibits adenyl cylase/ cAMP formation

Kinase-linked receptor rate of action + main molecule that targets it + relevance to cancer + 2 examples?

- Act slowly - Targeted by growth factors - Mutations lead to cancer - ECGR and PI3K

Nuclear receptors mechanism + molecules that target it?

Combines with steroid and moves to nucleus to alter genes + steroid hormones

Where does drug metabolism occur?

In the liver

Phase I metabolism reaction + key proteins?

- Catabolic reaction that increases polarity of drug via hydrolysis, oxidation etc. - P450 (CYP) monooxygenase proteins

Phase II metabolism reaction + common reaction?

- Chemical groups made in phase I are joined - Glucuronidation is a common reaction

3 ways drugs are excreted + short summary + most common method?

- Glomerular filtration (for unbound proteins) - Active tubular secretion (via OATs and OCTs) - MOST COMMON (90%) - Tubular reabsorption (passive diffusion of reabsorbed drug)

2 receptors that parasympathetic fibres act on?

Nicotinic ligand-gated channels and muscarinic GPCR

What can also be released from parasympathetic fibres apart from ACH + whay they cause?

VIP and NO + SM relaxation

What can also be released from sympathetic fibres apart from NA?

ATP and NPY

SM contraction summary?

- GPCR activates PLC - PLC produces IP3 - IP3 binds at SR and releases Ca - Ca binds calmodulin - Calmodulin activates MLCK - MLCK activates mysoin cross bridge

SM relaxation summary?

- GPCR activates AC - AC forms cAMP - cAMP activates PKA - PKA activates MLCK and MP - Calcium dissociates from calmodulin and MP inactivates cross bridge

Skeletal/cardiac contraction summary?

- GPCR activates AC - AC produces cAMP - cAMP activates PKA - PKA activates L-type Ca channels - CICR occurs - Ca binds tropomyosin C - Tropomyosin shifts actin out of cleft

Skeletal/cardiac relaxation summary?

- PKA activates phoshoplamban - Phospholamban increases CICR and relaxation rate - L-type channels close - Ca-ATPase reruits Ca back into SE - Ca dissociated from tropomysoin C

How is cAMP inactivated?

Phosphodiesterase (PDE)

cAMP role in muscle?

Activates PKA

PKA action in SM vs skeletal/cardiac?

Relaxation vs contraction AND relaxation

First order kinetics relationship + curve shape?

Rate of elimination = drug concentration + hyperbolic curve

Zero order kinetics relationship + curve shape?

Cp > Km of enzyme that metabolises it + linear curve

Clearance of a drug definition + what is applies to?

Volume cleared from plasma over time + only applies to first order kinetics

How is Ach vs NA taken back into pre-synaptic neurons?

Ach = enzyme degradation vs NA = reuptake channels (U1 and U2)

Effects of cocaine and amphetamine?

Increases adrenoreceptor stimulation so vascontriction, increased heart rate etc.

Sympathetic vs parasympathetic receptors in the smooth muscle + heart + vasculature?

Beta 2 and M3 + beta 1 and M2 + alpha 1