Pharmacology Flashcards
How do you calculate maintenance dose?
Maintenance dose = Cp(ss) x CL / Bioavailability
Where Cp(ss) is plasma conc at steady state and CL is clearance. Bioavailability is 1.0 for IV drugs. Note that the units are in mg/min
How do you calculate half life?
Vd x 0.7 / CL
Where Vd is volume of distribution and CL is clearance.
How do you calculate loading dose?
Loading dose = Vd x Cp(ss) / Bioavailability
Where Vd is volume of distribution and Cp(ss) is plasma conc at steady state.
Describe the site of action for the following diuretics:
Acetazolamide
Mannitol
Frusemide
Thiazides
Amiloride
Spironolactone
Carbonic anhydrase works at proximal tubule (HC03-)
Mannitol is an osmotic diuretic and works at the PT and dLH
Loop D’s work at the aLH (NaK2CL-)
Thiazides work at the DCT (NaCl sym)
Pot sparing D’s work at CD
Describe the site of action for the following diuretics:
Acetazolamide
Mannitol
Frusemide
Thiazides
Amiloride
Spironolactone

Define Clearance:
How do you calculate Clearance?
“The volume of plasma CLEARED of drug per unit time”
CL = rate of elimination of drug / plasma drug concentration
CL = Vd x Ke
What is zero-order elimination?
What are some classic examples?
The rate of elimination is constatn regardless of plasma concentration.
Examples include Phenytoin, Ethanol, and Aspirin.
What is first-order elimination?
The rate of elimination is proportional to the drug concentration, i.e. a constant fraction is being eliminated per unit time.
Applies to most drugs.
How does urine pH affect drug elimination?
How do we take advantage of that?
Ionized species are trapped in urine and cleared quickly.
Weak acids such as Aspirin, Phenobarbital, and Methotrexate are trapped in basic urine (Rx - Bicarbonate)
Weak bases such as Amphetamines and TCAs are trapped in acidic urine (Rx - Ammonium chloride)
What are the two phases of Drug Metabolism?
Which phase is affected in older age?
Phase 1 - Reduction, Oxidation, Hydrolysis with Cytochrome P450.
Phase II - Conjugation; Methylation, Glucoronidation, Acetylation, Sulfation.
Geriatric patient have More GAS (phase II > I)
Drug efficacy versus drug potency?

Describe the changes seen with Vmax and EC50 when competitive and non-competitive antagonists are introduced (with examples):

Describe the divisions of the autonomic nervous system in terms of:
Preganglionic NT and length
Postganglionic NTs and effector groups

Describe the general schematic of the secondary messenger system:

List 5 examples of secondary messenger systems:
cAMP system
Phosphoinisitol system
Tyrosine Kinase system
Arachidonic acid system
cGMP system
What are the G-protein-coupled receptors?
(Alpha and Beta Males Don’t Hate Vegans)
Alpha 1 and Alpha 2
Beta 1, 2, 3
Muscarinic 1, 2, 3
Dopamine 1 and Dopamine 2
Histamine 1 and 2
Vasopressin 1 and 2
Match the G-protein coupled receptor to their G-protein class:
(after QISSeS, you get a QIQ out of SIQ, Super Qinky Sex)
(A1=Q) (A2=I) (B1=S) (B2=S) (B3=S)
(M1=Q) (M2=I) (M3=Q)
(D1=S) (D2=I)
(H1=Q) (H2=S)
(V1=Q) (V2=S)
What are the roles, effector molecules, and secondary molecules of Gs, Gi, and Gq?
Gs = Stimulatory Gi = inhibitory
Gq = both
Gs and Gi use Adenyl cyclase and Protein Kinase A
Gq uses Phospholipase C and Protein Kinase C
What are the two broad classes of cholinomimetic agents?
Direct agonists of the ACh receptor
and
Anticholinesterases
List the direct choline agonists:
Bethanechol
Carbachol
Methacholine
Pilocarpine
What is the action and application of:
Bethanechol?
Carbachol?
Bethanechol activates bladder and bowel smooth muscle (ileus, urinary retention)
Carbachol is a carbon copy of ACh (constricts pupil and relieves pressure in OAG)
Both are resistant to AChE
What is the action and application of:
Methacholine?
Pilocarpine?
Methacholine stimulates M receptors in airways for asthma testing.
Pilocarpine is a potent stimulator of sweat, tears, and saliva (OAG, CAG, Xerostomia)
List the commonly used anticholinesterases:
What are their uses?
Galantine, Donepezil, and Rivastigmine (Alzheimer’s)
Edrophonium (Dx MG)
Neostigmine (Reversal NM blockade)
Physostigmine (Antidote for Ach toxicity)
Pyridostigmine (Long acting Rx for MG)
What is the pathophysiology of Organophosphate poisoning?
What are the characteristic signs/symptoms?
Organophosphates irreversibly bind AChE.
Diarrhoea, Urination, Meiosis, Bronchospasm, Bradycardia, Excitation of Skeletal muscle and CNS, Lacrimation, Sweating, Salivation.
Describe the type of drug, organ system, and application of:
Tropicamide
Benztropine
Glycopyrrolate
All are muscarinic antagonists:
Tropicamide - Eye - Mydriasis and Cycloplegia
Benztropine - CNS - Acute dystonia
Glycopyrrolate - GI - Reduce secretions
Describe the type of drug, organ system, and application of:
Hyoscyamine
Ipratropium
Oxybutynin
Scopolamine
All are muscarinic antagonists:
Hyoscyamine - GI - Antispasmodic
Ipratropium - Resp - COPD and Asthma
Oxybutynin - GU - Bladder spasm
Scopolamine - CNS - Nausea
What is the role of Atropine in Organophosphate poisoning?
Blocks DUMBBeLSS
Cannot block Excitation of CNS and Skeletal Muscle as these are mediated by nicotinic receptors.