PHARM Flashcards
What is KD?
Dissociation constant, concentration at which 50% receptors bound
What is Emax and EC50
Max- Measure of efficacy, maximum response at peak
50- Measure of potency, concentration to create 50% of max response
How many receptors are occupied in a maximum response for full agonists and partial agonists?
Full- not all
Partial- all
How does competitive surmountable antagonists alter agonist response?
Efficacy unchanged, potency reduced
What areas and affect do a and b adrenoreceptors have?
a1- constricts blood vessels, dilates pupil, constricts GIT
a2- inhibit transmitter release in nerves
b1- increase rate and force of heart, renin secretion in kidney
b2- skeletal muscle contractility, dilate bronchi
What are the 4 areas where non-competitive inhibition can occur?
- Chemical antagonism to chemically inactive, drugs or antibodies
- Allosteric modulation
- Pathway inhibition, multiple potential targets
- Functional antagonism, two agonists with opposite effects e.g. Na and Ach
What is bioavailability?
Proportion of administered drug that reaches circulation e.g prodrug that is metabolizes would have low, intravenous would have high
What is first pass metabolism?
Passing through liver to reach circulation, can be metabolized and form active molecules
What is volume of distribution?
The amount of drug in body divided by the concentration in plasma
What are the lengths of PS and S pre-ganglionic neurons?
PS long close to site of action
S short, to sympathetic chain
What are the neurotransmitters and receptors involved in somatic, PS, sympathetic for muscle organs, sympathetic for sweat glands and sympathetic for adrenal glands?
Somatic- No postganglionic, ACh to nicotinic (nAChR)
PS- ACh to nAChR on postganglionic (same for all postganglionic), ACh to muscarinic (mAChR)
S, muscle/organs- ACh to nAChR on postganglionic, noradrenaline to ab adrenoreceptors
S, sweat- ACh to nAChR on postganglionic, ACh to mAChR
S adrenal- ACh to nAChR on postganglionic, Adrenaline to circulation and ab adrenoreceptors in tissue
What are the steps of chemical transmission?
- AP, membrane depolarisation
- Synthesis
- Storage
- Ca2+ dependent vesicular exocytosis
- Receptor activation
- Reuptake
- Degradation
How can catecholamine production be altered (3)?
- L-DOPA, product of rate limiting stepped, increases NA/A
- Carbidopa, DOPA decarboxylase inhibitor which turns L-DOPA to dopamine
- VMAT inhibitor (e.g. reserpine), inhibits dopamine uptake into vesicles by VMAT where dopamine is converted to noradrenaline
What is the primary and secondary reuptake process?
Primary: NET into neuron
Secondary: OCT3 extraneuronally
What metabolizes noradrenaline at the nerve terminal?
Monoamine oxidase (MAO)
What drugs interfere with the reuptake process (3)?
- Tricyclic Antidepressants (TCA’s) inhibit NET, prevent reuptake, longer presence in junction and increased binding
- MAO inhibitors, noradrenaline not metabolized, more can enter vesicles
- Indirectly-acting Sympathomimetics (IAC’s) e.g. ephedrine, similar structure to NA, uptake by NET, displace NA in vesicles, NA can exit neurons via NET and have bind in junction
How can acetylcholine synthesis and storage be inhibited (3)?
- Hemicholinium (experimental) blocks high affinity choline transporters (rate limiting step), which will transport choline (ACh precursor) into the neuron
- Vesamicol (experimental) blocks vesicular acetylcholine transporter from transporting ACh into the vesicle to be released into the junction
- Botulinum Toxin, heavy chain binds irreversibly to receptors for neurons containing ACh, endocystosed, light chain cleaves SNARE proteins, SNARE complex cannot form and vesicle and membrane cannot fuse
What are the symptoms of Botulinum poisoning?
Facial weakness, difficulty swallowing, limb paralysis, anti-SLUD (salivation, lacrimation, urination, defecation) dry mouth, dry eyes, urinary retention, constipation
What drugs interfere with cholinergic metabolism at neuromuscular junction (3)?
- Anticholinesterases prevent acetylcholinesterases from metabolizing ACh into choline
- d-Tubocurarine, competitive reversible antagonist of nAChR postjunction, allows skeletal m. relaxation during surgery
- Suxamethonium, nAChR agonist, causes prolonged depolarization, muscle relaxes as it cannot undergo repolarization
What is Myasthenia Gravis and how is it treated?
Muscle weakness caused by auto-antibodies degrading nAChRs meaning ACh is degraded before getting a big enough response. Eye movement, swallowing, facial expression first effected then limbs.
Neostigme is a reversible anti-cholinesterase specific for neuromuscular junction. Prevents ACh metabolism, bigger response.
Muscarinic Effects, SLUDGE, DUMBBELS
Salivation, Lacrimation, Urination, Diarrhea, GIT upset, Emesis (vomiting)
Diarrhea/Diaphoresis (sweating), Urination, Miosis (pupil contracted), Bradycardia/Bronchospasm, Emesis/excitation, Lacrimation/Lethargy, Salivation
Where are M2 and M3 receptors found?
M2- heart
M3- glandular smooth muscle
What are N1 and N2 receptors?
N1- neuromuscular junction
N2- autonomic ganglia
What are high nicotinic and muscarinic agonists?
Nicotinic- Acetylcholine, Carbachol, Nicotine
Muscarinic- Acetylcholine, Methacholine, Bethanechol, Muscarine
What is atropine?
Muscarinic antagonist, stops secretions (DUMBBELS) during surgery
What are some modifiable and non-modifiable risk factors for CVD?
Non-mod- age, sex, ethnicity, family history
Mod- diet, exercise, substance abuse
Function of CVD?
DR MED
Distribute hormones, essential substances, heat
Remove metabolic by-products
Mediate inflammatory factors
What factors affect cardiac output?
Stroke volume, volume ejected per beat
Heart rate