Pharmacology One-liners 1 Flashcards
Half-life (T1/2)
Time it takes for amount of drug to fall to half its value, constant in first order kinetics (majority of drugs)
Volume of distribution (VD)
Relates the amount of drug in the body to the plasma concentration
Cp
Plasma concentration of a drug at a given time
Clearance (CL)
The ratio of the rate of elimination of a drug to its plasma concentration
First pass effect
Hepatic metabolism of the drug before it reaches the systemic circulation
Bioavailability (F)
The fraction of unchanged drug that reaches systemic circulation after administration
Steady state
When the rate of drug input equals the rate of drug elimination
Different Steps of Phase I
Oxidation
Reduction
Hydrolysis
Inducers of CYP450
Rifampin Phenobarbitol Carbamazepine Phenytoin St. John's wort
Inhibitors of CYP450
Macrolides Ketoconazole (azoles) Ritonavir (protease inhibitors) Cimetadine Grapefruit juice Quinidine Amiodarone
Phase II Conjugation reactions
Glucuronidation Acetylation Glutathione conjugation Glycine conjugation Sulfation Methylation Water conjugation
First-order kinetics
Constant percentage of drug metabolized per unit time
Zero-order kinetics
Constant amount of drug metabolized per unit time
Loading dose
Cp x (Vd/F) Target plasma concentration times [volume of distribution/bioavailability]
Maintenance dose
Cp x (CL/F) Concentration in the plasma times [clearance/bioavailability]
Affinity
Strength of interaction between drug and its receptor
Specificity
Selectivity of a drug for its receptor
Potency
Amount of drug necessary to elicit a biological effect compared with another drug
Efficacy
Ability of a drug to produce the maximal biological effect
Full agonist
Ability of a drug to produce maximal response after binding to the receptor
Partial agonist
Ability to produce less than maximal response after binding to the receptor
Competitive antagonist
Ability to bind reversibly to the same site as the drug and without activating the effector system
Noncompetitive antagonist
Ability to bind irreversibly to the active site or bind to a site distinctly separate from the agonist binding site
Which substances use an intracellular receptor as the mechanism of action?
Steroids
Hormones
Which substances use transmembrane receptors that have intrinsic enzymatic activity as the mechanism of action?
Insulin EGF TGF-beta PDGF ANP
Which substances use ligand-gated ion channels in the mechanism of action?
Acetylcholine
Nicotine
ED50
Dose that produces therapeutic response in 50% of the population
TD50
Dose that is toxic to 50% of the population
LD50
Dose that is lethal to 50% of the population
Therapeutic index
Window between therapeutic effect and toxic effect
High therapeutic index
Indicates drugs that have a high margin of safety
Low therapeutic index
Indicates drugs that have a narrow margin of safety
Antidote for lead poisoning
Edetate calcium disodium
Succimer
Dimercaprol
Antidote for cyanide poisoning
Nitrates
Thiosulfate
Hydroxocobalamin
Antidote for anticholinergic poisoning
Physostigmine
Antidote for organophosphate or acetylcholinesterase poisoning
Atropine Pralidoxime (2-PAM)
Antidote for iron salt poisoning
Deferoxamine
Antidote for acetaminophen poisoning
N-acetylcysteine
Antidote for arsenic, mercury, and gold poisoning
Dimercaprol
Succimer
Antidote for Wilson’s disease (copper poisoning)
Penicillamine
Antidote used for heparin toxicity
Protamine Sulfate
Antidote used for warfarin toxicity
Vitamin K1 and fresh frozen plasma
Antidote for tissue plasminogen activator (t-PA), streptokinase
Aminocaproic acid
Antidote for methanol and ethylene glycol toxicity
Fomepizole
Ethanol
Antidote for opioid toxicity
Naloxone (IV)
Antidote for benzodiazepine toxicity
Flumazenil
Antidote for tricyclic antidepressants (TCA)
Sodium bicarbonate (alkalinize plasma)
Antidote for carbon monoxide poisoning
100% O2 and hyperbaric O2
Antidote for digitalis toxicity
Digibind
Antidote for methotrexate toxicity
Leucovorin
Antidote for beta-blocker overdose
Glucagon
Method to reduce salicylate intoxication
Sodium bicarbonate (alkalinize urine) Dialysis
This agent has greater affinity for muscarinic receptors and used for postoperatives and neurogenic ileus and urinary retention
Bethanechol
Muscarinic that is very lipid soluble and used in glaucoma
Pilocarpine
Muscarinic used to treat dry mouth in Sjogren’s syndrome
Pilocarpine
Cevimeline
Toxicity of cholinergics
DUMBELSS Diarrhea Urination Miosis Bronchoconstriction Excitation of skeletal muscle/CNS Lacrimation Salivation Sweating
Edrophonium
Cholinesterase inhibitor, short duration of action, used in diagnosis of myasthenia gravis
Neostigmine
Cholinesterase inhibitor, intermediate duration of action, used off-label for postoperative paralytic ileus and urinary retention
Physostigmine
Cholinesterase inhibitor, lipid soluble, indicated for atropine overdose and glaucoma
Pyridostigmine
Treatment of myasthenia gravis and sometimes used prophylactically for organophosphate poisoning in chemical warfare
Echothiophate
Organophosphate, indicated for glaucoma but not used much clinically due to long duration of action
Organophosphate insecticides
Malathion
Parathion
What is the most important cause of acute deaths in cholinesterase inhibitor toxicity?
Respiratory failure
Atropine
Used in treatment of muscarinic symptoms in organophosphate overdose
Mechanism of atropine
Nonselective antimuscarinic
Benztropine
Antimuscarinic that treats Parkinsonism and extrapyramidal disease
Scopolamine
Antimuscarinic for the treatment of motion sickness
Which drugs produce mydriasis and cycloplegia?
Atropine, anti-muscarinics
2 antimuscarinics that cause bronchodilation in asthma and COPD
Ipratropium
Tiotropium
Oxybutynin
Antimuscarinic indicated for overactive bladder muscle dysfunction
Mnemonic for anticholinergic toxicity
Dry as a bone, red as a beet, mad as a hatter, hot as a hare, blind as a bat”
What is the most dangerous effect of anticholinergic toxicity in what age group?
Atropine fever
Infants
Contraindications for use of atropine
Infants
Closed-angle glaucoma
Prostatic hypertrophy
Menmonic for beta receptors
1 heart (B1) 2 lungs (B2)
Drug of choice for anaphylactic shock
Epinephrine
Methamphetamine
Indirect acting sympathomimetic, reuptake inhibitor, commonly abused
Indicated for attention deficit disorder and weight reduction
Phenylephrine
Alpha agonist indicated for nasal congestion, hypotension, and mydriasis induction
Albuterol
Short acting Beta 2 agonist, drug of choice for acute asthma
Salmeterol
Longer-acting beta 2 agonist, indicated for prophylaxis of asthma
Its ability to increase heart rate makes it useful as adjunct therapy for acute heart failure and hypovolemia or septic shock
Beta 1 agonist
Its ability to vasoconstrict and increase blood pressure makes it useful as local decongestant and for the therapy of spinal shock (temporary maintenance of blood pressure)
Alpha 1 agonist
Alpha 1 agonist toxicity
Hypertension
Midodrine
Indicated for symptomatic orthostatic hypotension
Terbutaline
Beta 2 agonist used to suppress premature labor, but cardiac stimulatory effects may be hazardous to mother and fetus
Ephedrine
Indirect acting sympathomimetic, improves urinary continence in children and elderly with enuresis
Beta agonists used in acute congestive heart failures
Dobutamine and dopamine
Beta 1 agonist toxicity
sinus tachycardia and serious arrhythmias
Beta 2 agonist toxicity
Skeletal muscle tremor
Phenoxybenzamine
Irreversible, nonselective alpha-blocker indicated for pheochromocytoma
Phentolamine
Reversible, nonselective alpha blocker indicated for pheochromocytoma
Prazosin, terazosin, doxazosin
Selective alpha 1 blocker used for hypertension, benign prostatic hyperplasia, may cause first dose orthostatic hypotension
Tamsulosin
Alpha 1a-selective blocker used for benign prostatic hyperplasia
Side effects of alpha blockers
Orthostatic hypotension (especially w/ first dose) and reflex tachycardia
Selective Beta-1 receptor blockers useful for treating cardiac conditions in patients with asthma
ABEAM Acebutolol Betaxolol Esmolol Atenolol Metoprolol
Labetalol/carvedilol
Blocks alpha 1 and beta receptors and indicated for the treatment of CHF
Pindolol/acebutolol
Beta blockers with partial agonist activity, can bronchodilate and may have an advantage treating patients with asthma
Timolol
Non-selective beta blocker that lacks local anesthetic activity, indicated for glaucoma
Esmolol
short-acting beta blocker that can be given parenterally
Clinical uses of beta blockers
Treatment of hypertension, angina, arrhythmias, and chronic congestive heart failure
Side effects of Beta blockers
Bradycardia, AV block, impotence, dyslipidemia, exacerbation of COPD
Beta-blockers should be used cautiously in
Asthma (bronchospastic effects)
Diabetes (block signs of hypoglycemia)
Peripheral vascular disease
Beta blockers’ effect on the heart in antianginal therapy
Reduce heart rate, blood pressure, contractility, and increase end-diastolic volume
DOC for Classic (exertional) angina
Beta blockers
Carvedilol
A nonselective beta blocker with alpha 1 blocking effect; indicated for congestive heart failure
Class of drugs which inhibit angiotensin-converting enzyme
ACE Inhibitors
Captopril/enalapril
ACE Inhibitors
End in -pril
Side effects of ace inhibitors
Dry cough
Hyperkalemia
Angioedema
Bradykinin
Inactivated by angiotensin converting enzyme contributes to dry cough and angioedema
Contraindication to angiotensin-converting enzyme inhibitors
Pregnancy
Hyperkalemia
Mechanism of action of losartan/valsartan
Block AT1 receptors
Side effect associated with ace inhibitors but not arb blockers
Dry cough
Mechanism of action of calcium channel blockers
Block L-type calcium channels
Ca2+ channel blockers w/ predominant effect on arteriole dilation
Dihydropyridines
Nifedipine
Amlodipine
Nimodipine
Ca2+ channel blockers w/ predominant effect on the heart
Non-dihydropyridines
Verapamil
Diltiazem
Side effects of Ca2+ channel blockers
Constipation
Peripheral edema
Cardiac depression
AV block
Methyldopa
Alpha 2 agonist used in pregnant women with hypertension
Side effects of methyldopa
Positive Coomb’s hemolytic anemia
SLE-like syndrome
CNS depression
Methyldopa contraindicated in
Geriatrics due to its CNS depression effects
Side effects of clonidine
Rebound hypertension, sedation, dry mouth