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26 Cards in this Set
- Front
- Back
Bioavailability
Half-life |
IV ~ 100%
F = (AUCpo*Div)/(Dpo*AUCiv) t1/2 = .7*Vd/CL |
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Dosage Calculations--
Loading dose Maintenance dose |
LD: = Cp*Vd/F
MD: = Cp*CL*dose interval Cp-plasma concentration at steady state Steady state typically reached in 4-5 half-lives |
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Elimination of drugs--
Zero-order First-order |
Z: constant amount eliminated per unit time; PEA--**Phenytoin, Ethanol, Aspirin**
F: constant percentage per unit time |
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Urine pH and drug elimination--
Weak acids Weak bases |
Ionized species are trapped in urine and cleared quickly
WA: phenobarbital, MTX, ASA; trapped in basic environment; Tx is NaBicarb WB: amphetamines; trapped in acidic environment; Tx is ammonium chloride |
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Drug metabolism--
Phase I Phase II |
I: reduction, oxidation, hydrolysis w/P450; geriatrics lose this first
II: conjugation (glucuronidation, acetylation, sulfation); geriatrics typically have this ability |
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Therapeutic index--
Calculation Examples of drugs w/low TI |
'TITE'
TI = TD50/ED50 Examples: digoxin, lithium, theophylline, warfarin |
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ACh receptors--
Nicotinic Muscarinic |
N: ligand-gated Na/K channels; Nn found in autonomic ganglia and Nm are found in NMJ
M: G-protein coupled receptors; M1-5 subtypes **Muscarinic agonists will always increase secretions (sweat included) |
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Innervation of eye & affect--
Sphincter muscle Radial muscle Ciliary muscle |
S: muscarinic receptors; miosis
R: a1 receptors; mydriasis C: muscarinic receptors; accomodation |
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G-protein linked 2nd messengers
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"QISS and QIQ till you're SIQ of SQS (super qinky sex)"
a1, a2, b1, b2--QISS a1--pupillary dilator m.; GI sphincter contraction b1--heart, renin release b2--insulin release; relaxes uterus; aqueous humor production M1-3--QIQ M2--heart rate M3--secretions, bladder contraction, bronchoconstriction, miosis, accomodation D1, D2--SI D1--relaxes renal vascular tone H1, H2--QS V1, V2--QS |
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Random drugs--
Hemicholinium Metyrosine Reserpine Botulinum Amphetamine Cocaine, TCAs, amphetamine |
H: blocks choline uptake into cholinergic nerve
M: blocks tyrosine hydroxylase-->can't convert tyrosine to DOPA R: inhibit storage of DA in vesicles; *risk of suicide* B: prevents release of ACh vesicles at nerve terminal A: stimulates vesicle release of NE C, T, A: blocks reuptake of NE into nerve terminal |
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Cholinomimetic direct agonists--
Bethanechol Carbachol Pilocarpine Methacholine |
All cause bradycardia, inc secretions, diarrhea, miosis
B: postop ileus; urinary retention; resistant to AChE C: glaucoma P: "you cry, drool and sweat on your PILOw"--CF sweat test, both types of glaucoma M: challenge test for asthma (bronchial hypersensitivity) *may exacerbate COPD, asthma, peptic ulcers* |
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Cholinomimetic indirect agonists--AChE inhibitors
Neostigmine Pyridostigmine Physostigmine Donepezil Edrophonium |
Activates both N and M muscarinic receptors
N: "NeO CNS"; also for MG, postop ileus Py: gets RID of myasthenia gravis Ph: "phyxes" atropine overdose; uncharged and cross BBB D: Alzheimer disease E: dx of MG *may exacerbate COPD, asthma, peptic ulcers* |
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Cholinesterase inhibitor poisoning
Symptoms Tx |
Due to organophosphates such as parathion or malathion; irreversibly inhibit AChE & affects both muscarinic and nicotinic receptors; antidote only fixes muscarinic blockade, may see NMJ issues
Sx's: diarrhea, miosis, sweating, lacrimation, salivation, bradycardia, bronchospasm, urination Tx: atropine + pralidoxime (2-PAM) 2-PAM--regenerates AChE |
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Atropine toxicity
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"Hot as a hare, Dry as a bone, Red as a beet, Blind as a bat, Mad as a hatter"
--increased body temp (dec sweating), tachycardia; dry/flushed skin; dry mouth; cycloplegia; disorientation (confusion) **Jimson weed can cause similar effects **Tx is physostigmine |
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Sympathomimetics--direct
Epi NE Isoproterenol Dopamine Dobutamine Phenylephrine Albuterol, salmeterol, terbutaline |
E: b>a; low dose--b; high dose--a; anaphylaxis, htn,
NE: a1>a2>b1; htn (reflex bradycardia) Iso: b1=b2 DA: D1=D2>b>a; only symp drug to increase renal blood flow while also correcting htn Do: b1>b2; heart failure P: a1>a2; htn, rhinitis A/S/T: b2 |
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Sympatholytics--
Clonidine a-methyldopa Phenoxybenzamine Phentolamine Prazosin Mirtazapine |
C: a2 agonist; used in hypertensive urgency; may cause CNS depression
a-m: a2 agonist; used for HTN in pregnancy Px: irreversible, nonselective a-blocker; pheochromocytoma (preop) Pa: reversible nonselective a-blocker; pts on MAO inhibitors who eat tyramine-containing foods (cheese, wine) Pr: a1 selective blocker; BPH, PTSD; HTN M: a2 selective blocker; depression |
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b-blockers
Special notes Selectivity Toxicity |
Sn: dec mortality in MI; dec renin secretion (b1); dec secretion of aqueous humor
S: A-M b1 selective; N-Z nonselective; carvedilol/labetalol are nonselective a & b antagonists T: **impotence, AV block, CNS adverse effects; may exacerbate COPD or asthma |
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Drug rxns--cutaneous flushing
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"VANC"
Vancomycin Adenosine Niacin Ca channel blockers |
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Drug rxns--aplastic anemia
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"Can't Make New Blood Cells Properly"
Carbamazepine, Methimazole, NSAIDs, Benzene, Chloramphenicol, Propylthiouracil |
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Drug rxns--fat redistribution
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"Fat PiG"
Protease inhibitors Glucocorticoids |
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Drug rxns--SLE-like syndrome
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"SHIPPE"
Sulfa drugs, Hydralazine, INH, Procainamide, Phenytoin, Etanercept All metabolized by N-acetylation--slow acetylators have increased risk for developing drug-induced lupus |
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Drug rxns--seizures
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"With seizures, I BITE My tongue"
INH (B6 deficiency) Bupropion Imipenem/cilastatin Tramadol Enflurane Metoclopramide |
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Drug rxns--antimuscarinics
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Atropine, TCAs, H1-blockers, antipsychotics
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Drug rxns--disulfiram-like rxn
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Metronidazole, griseofulvin, procarbazine, 1-gen sulfonylureas
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Drug rxns--nephrotoxicity
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Aminoglycosides, vancomycin, loop diuretics, cisplatin
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Drug rxns--pulmonary fibrosis
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Bleomycin, amiodarone, busulfan, methotrexate
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