• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

Card Range To Study

through

image

Play button

image

Play button

image

Progress

1/104

Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

104 Cards in this Set

  • Front
  • Back
Acetazolamide
Diamox Carbonic anhydrase inhibitor Site 1 (prox tubule) Block Na+/H+ antiporter; inhibits HCO3- reabsorption & carbonic anhydrase ↓ CSF & intraocular volume Glaucoma, epilepsy, acute mountain sickness Alkalinized Urine --> Hyperchloremic Metabolic acidosis DI with Memantine
Furosemide
Lasix High-ceiling ("Loop") Site 2 (Asc. Limb) Block Na+/K+/2Cl- (NKCC2 transporter); acts on tubular side of cell; effective natriuretic; ↑ renal blood flow Diuresis; vasodilator Edema (acute and/or pulmonary), ↑ Ca2+; HTN in pts w ↓ renal blood flow PO or subq Half-life = 50 min Hypokalemia, ototoxicity, hypochloremic metabolic alkalosis, hyperglycemia, hyperuricemia, hypertriglyceridemia, GI problems, hypomagnesemia, hypotension must be secreted into proximal tubule; counter-current washout; DI w/ COX inhibitors, propranolol, organic acids, albumin binders
Bumetanide
Bumex High-ceiling Site 2 NKCC2 blocker; 4x as potent as furosemide Diabetic pts or pts allergic to furosemide Less hyperglycemia OH DANG!- ototoxicity, hypokalemia, dehydration, allergy (sulfa), nephritis, gout
Ethacrynic acid
Edecrin High-ceiling Site 2 NKCC2 blocker w/o sulfonamide group Pts w/ sulfa allergy More GI problems, less hyperglycemia
Torsemide
Demedex High-ceiling Site 2 NKCC2 blocker w/ 2x greater bioavailability Long half-life (QD dose)
Chlorothiazide
Diuril Thiazide Site 3 (DCT) Block Na+/Cl- cotransport; produce hyperosmolar urine Long-term therapy HTN management, CHF, hypercalciuria, mild edema, diabetes insipidus PO Long half-life, 1-3 weeks for effect ↓ K+ (supplement with K+ diet, salts, or spironolactone); ↓ Na+; hyperuricemia; orthostatic hypotension, ↑ Ca2+, ↑ glucose, hyperlipidemia (may return to normal); hypersensitivity; impaired excretion of Li+; metabolic alkalosis; toxic with digitalis; decrease renal BF Not useful if GFR < 30 ml/min
Hydrochlorothiazide
Hydrodiuril Thiazide Site 3 NCC blocker, more potent than CTZ
Spironolactone
Aldactone K+-sparing Site 4 (Collecting tubule) Aldosterone receptor antagonist (competitive); blocks aldosterone Na+/K+ exchange; inhibits K+ loss Slight Na+ excretion & diuresis K+ protection from diuretics; strong action in CHF or liver cirrhosis, hyperaldosteronism PO with food Slow on/off (steroid action) Hyperkalemia (bad in DM or ↓ GFR); gynecomastia, impotence, menstrual irregularities never with physiological antagonist
Eplerenone
Ispra K+-sparing Site 4 Specific mineralocorticoid receptor antagonist Combo w/ site 3 diuretics HTN, post-MI, K+ protection Hyperkalemia
Triamterene
Dyrenium K+-sparing Site 4 Physiologic antagonist of aldosterone (electrogenic, fast-acting); inhibits Na+ channel influx, dissipates transepithelial potential PO Half-life = 3 hours Rare nephrotoxicity w/ indomethacin
Amiloride
Midamor K+-sparing Site 4 PO Half-life = 6-9 hours hyperkalemia, increased Li reabsorption, elevate urate
Dopamine
Hemodynamic a1, b1, DA receptor agonist ↑ blood flow & GFR, ↓ counter-current exchange Renal vasodilator w/ dobutamine post-MI
Caffeine
Hemodynamic Vasa recta
Mannitol
Osmotic Plasma compartment Countercurrent washout, 4 attributes: inert, osmotically active, filtered not reabsorbed, not metabolized; prevent reabsorption of water Cerebral edema, glaucoma, prophylaxis of acute renal failure IV Excess CSF volume if removed rapidly: HA, nausea, vomiting; contraindicated in anuria, peripheral edema, CHF, & dehydration
Isosorbide
Osmotic Plasma compartment Eye surgery IV or PO
Propranolol
β-blocker Antagonize stretch receptors and ↓ renin release HTN, tremor Ineffective when plasma renin activity is low
Clonidine
"α2-agonist/CNS adrenolytic
" HTN
Methyldopa
CNS adrenolytic HTN
Captopril
Capoten PDP (ACE) inhibitor; has sulfhydryl group Block conversion of angiotensin I to II. ↑ Renin release ↓ blood pressure & aldosterone secretion HTN (w/ DM nephropathy), CHF, angina, post-MI PO w/o food Half life= 1.5-2 hours Hypoglycemia w/ insulin (due to sulpher moeity) proteinuria, hypogustia, hypersensitivity, cough, neutropenia; DO NOT use in combination with triamterene or amiloride: hyperkalemia
Enalapril
Vasotec PDP inhibitor; has carboxyl group; prodrug → enalaprilat (active) PO w/ or w/o food; IV enalaprilat Half-life = 11 hours (QD dose) fewer side effects
Lisinopril
Zestril PDP (ACE) inhibitor PO w/ or w/o food Half-life = 12 hours no plasma binding
Benazepril
Lotensin most potent PDP inhibitor
Losartan K
Cozaar Angiotensin II receptor antagonist Blocks binding of angiotensin II to AT-1 receptors Alone or + HCTZ (Hyzaar) PO Half-life of metabolite = 9 hours Dizziness, hyperkalemia excreted in bile
Valsartan
Diovan Angiotensin II receptor antagonist Alone or + HCTZ (Diovan HCT) PO w/o food
Aliskiren
Non-Peptide Renin Inhibitor "Blocks production via the classical pathway of all forms of angiotensins.
" PO poor bioavailability (3%) but long half life Diarrhea, hyperkalemia Does not inhibit kinins
Fludrocortisone
Aldosterone agonist Mineralocorticoid Given w/ glucocorticoid Adrenal insufficiency PO
DOCA (deoxocorticosterone acetate)
Aldosterone agonist IV or IM (in oil)
Spironolactone
Aldactone Aldosterone competitive antagonist Binds to mineralocorticoid, androgen & progestin receptors HTN, CHF weakly diuretic
Eplerenone
Inspra Aldosterone competitive antagonist more specific mineralcorticoid agonist HTN, post-MI
Triamterene
Aldosterone physiological antagonist DO NOT use with ACE inhibitors K+ sparing
Amiloride
Aldosterone physiological antagonist
Allopurinol
Zyloprim Xanthine oxidase inhibitor Inhibits biosynthesis of uric acid (competitive antagonist) Long-term therapy Chronic, tophagous gout w/ ↑ urate production, ↓ renal function PO May precipitate gout attack on initiation of therapy; GI sx, skin rash, hypersensitivity; drug interactions Use if hypersensitivity to uricosuric agents
Febuxostat
Uloric Xanthine oxidase inhibitor Inhibits biosynthesis of uric acid (more specific than allopurinol) Reduced frequency of hypersensitivity compared to allopurinol Increased CV adverse effects
Colchicine
Impairs chemotaxis of granulocytes into gouty joints Acute therapy or + probenecid Acute gout attacks Nausea & vomiting Most likely interferes with tubulin activity
Pegloticase
Krystexxa Uricase Recombinant Exogenous enzyme (uricase) oxidizes uric acid to alltoin (highly water soluble) Acute reduction of serum urate Treatment of gout unresponsive to standard therapy IV infusion
Probenecid
Benemid Uricosuric High doses ↑ urate excretion, ↓ urate reabsorption & secretion (competitive inhibition) Long-term therapy Chronic gout or 1-shot treatment of uncomplicated gonococcal + long-acting penicillin (blocks secretion) PO GI problems, kidney stones, hypersensitivity; Low dose: "paradoxical effect" ↓ urate excretion and ↑ plasma urate; aspirin prevents actions on urate; additive actions with sulfinpyrazone; antagonizes diuretics highly lipid soluble; passive reabsorption from nephron
Sulfinpyrazone
Anturane Uricosuric Metabolite of phenylbutazone, strong acid; ↑ urate excretion Chronic gout w/ hypersensitivity to probenecid More GI problems, less hypersensitivity antithrombotic properties of unknown mechanism
Ethanol
alcohol Sedative- hypnotic Binds to GABAa receptor to open Cl- channels; inhibits NMDA glutamate receptors rapidly absorbed by GI; Liver EtOH dehydrogenase or MEOS → aldehyde dehydrogenase → acetate (uses NADH/NADPH) zero-order kinetics: 1 drink(6-8g)/hr Methanol toxicity Disinhibition, CNS depression (ataxia, slurred speech, coma, delirium); risk of aspiration, vasodilation, cardiac depression, diuresis, blackouts Cirrhosis, pancreatitis, PUD, malnutrition, CA, FAS, Wernicke- Korsakoff thymine deficiency (causes neuropathy, confusion) Anxiety, insomnia, anorexia, sympathetic autonomic hyperactivity, delirium tremens, seizures; subsides within 3-7 days OD: supportive, prevent aspiration; Chronic: rehab, thiamine; Withdrawal: BZ for seizure, haldol, clonidine Inhibits metabolism and duration of warfarin and phenytoin; contraindicated with drugs irritating the GI; cross-tolerance w/ benzodiazepines & barbiturates
Disulfiram
Adjunct to treat alcoholism
Naltrexone
Alcoholism
Acamprosate
Alcoholism
Methanol
Blurred vision, blindness, seizures, coma, acidosis Supportive therapy, ethanol Necrosis of bilateral putamina & claustra, toxic to retinal ganglion cells
Ethylene Glycol
renal insufficiency/injury due to metabolic acidosis and oxalate deposition in the kidney. Ethanol, Fomepizole
Thiopental
IV general anesthesia Drowsiness, respiratory depression; induce hepatic δ-aminolevulinic acid synthase (worsen acute intermittent porphyria); add to EtOH CNS depression; ↑ metabolism of steroid hormones (hepatic microsomal enzymes) Cellular & enzymatic tolerance; physical dependence Anxiety, insomnia, anorexia, autonomic hyperactivity (similar to EtOH) Respiratory support, gastric lavage, hemodialysis, osmotic diuretics cross-tolerance w/ other sedative=hypnotics
Pentobarbital
Preanesthesia, regional anesthesia
Phenobarbital
Epilepsy, w/drawal from Sedative-Hypnotics; congenital hyperbilirubin, neonatal jaundice
Cocaine
Topical anesthesia (inherent vasoconstriction) Euphoria, ↑ activity, ↓ appetite, sympathetic stimulation, sexual arousal; insomnia, anxiety, tachycardia, HTN, sexual dysfunction Huge tolerance; anxiety, insomnia, psychological dependence; CVA, seizure, coronary vasospasm, MI, psychosis; nasal perforation, "crack baby" (cocaine) Crash: anxiety, fatigue, hypersomnia, hunger; Withdrawal: drug craving, anhedonia, depression, dysphoria
Amphetamine
ADHD, narcolepsy (+) necrotizing arteritis
Nicotine
Patch, gum, inhalant for nicotine dependence ↑ motor activity, cognitive function, ADH, ↑ BP & HR, GI tract tone; ↓ appetite, N&V CANCER, Cellular, some metabolic tolerance; develops rapidly, long-lasting; psychological dependence ↓ DA in nucleus accumbens; craving, tremor, dizziness, irritability, anxiety, ↑ appetite Nicotine treatments + behavioral therapy; may use antidepressants: Bupropion; Varenicline (nicotine receptor antagonist) It's the smoooooooke..., crosses placenta
Marijuana/Dronabinol
N&V from CA chemo, appetite stimulant in AIDS; ↓ intraocular pressure in glaucoma; neuropathic pain Euphoric state, ↑ appetite, relaxation; tachycardia, red eyes, laughter, inattention, tremulosness, ↓ ST memory Lung damage from smoke; cognitive impairement No demonstrated physical dependence/ withdrawal syndrome
LSD
Dilated pupils, ↑ BP, tachycardia; Good Trip: altered consciousness, euphoria, ↑ sensory awareness, introspection; Bad Trip: anxiety, agitation, panic reactions, psychosis, hallucinations Tolerance, cross-tolerance w/ LSD, psilocybin, mescaline BZ and therapy
Phencyclidine
Euphoria, personality dissociation, poor judgment, aggression, psychosis; hallucinations, seizures, respiratory depression, coma; renal failure, rhabdomyolysis Induced vomiting, respiratory support, seizure control w/ BZ, reduce sensory stimulation
Hydrochlorothiazide
HCTZ Thiazide diuretic ↓ reabsorption of Na+; loss of Cl-, K+, Mg2+, water ↓ vascular volume, ↓ TPR HTN, CHF, hypercalciuria, diabetes insipidus Hypokalemia, hyponatremia, gout, volume depletion First step therapy for prevention of HF
Furosemide
Lasix Loop diuretic Inhibits Na+/K+/Cl- cotransport ↓ vascular volume, ↓ TPR CHF, pulmonary edema (acute, rapid onset) Ototoxicity, hypokalemia, gout, hypovolemia, hypomagnesemia
Spironolactone
Aldosterone competitive antagonist (K+ sparing) K+ retention, Na+ excretion ↓ vascular volume CHF, cirrhosis Hyperkalemia with ACE Inh or ARB; gynecomastia, GI upset, mental confusion
Eplerenone
Aldosterone competitive antagonist (K+ sparing) K+ retention, Na+ excretion ↓ vascular volume CHF, cirrhosis Hyperkalemia with ACE Inh or ARB; gynecomastia, GI upset, mental confusion
Amiloride
Dyrenium K+-sparing Physiologic antagonist of aldosterone (electrogenic, fast-acting); inhibits Na+ channel influx, dissipates transepithelial potential
Atenolol
Tenormin β1-blocker ↓ BP, afterload ↓ CO, ↓ renin activity HTN Less bronchial constriction; careful in CHF, asthma, COPD, and heart block pts QD or BID; longer T1/2 than metoprolol
Propranolol
Inderal β antagonist Equal β1 and β2; blocks NE and Epi blocks cardiostimulatory effects of NE and Epi and thus ↓ cardiac output, blocks β1 renin release and thus angiotensin formation (↓ O2 demand); crosses BBB HTN, arrhythmia, angina, migraine prophylaxis, anxiety, essential tremor reduction Careful in heart failure; blocks B2→worsens asthma, COPD, and emphysema; hypoglycemia; allergy complications; abrupt cessation of B antagonist can precipitate angina and increase risk of sudden death "PO has poor bioavalibility, 3-4 hours (large first-pass effect), competitive antagonist lipophilic & crosses BBB

"
Prazosin
Minipress α1 antagonist Blocks vascular α-1 receptors, arterial & venous: blocks NE effects Relax smooth muscle, vasodilation Benign prostatic hypertophy (BPH), mild to moderate HTN; heart failure (↓ pre- and afterload) Orthostatic hypotension, inhibits ejaculation, little reflex tachycardia "3 hour half-life (liver metabolism), not block A2 receptors & does not increase neural release of NE
"
Carvedilol
CoReg α1 antagonist, β antagonist *Pan beta (1&2) blocker→decreases cardiac, arterial, and kidney effects of B1&2 actions of NE *alpha 1 blocker→decreases vasoconstriction and BP *antioxidant→counteracts production of O2 radicals CHF Used with ACE inhibitors and diuretics; blocks ischemia, further damage
Clonidine
Catapres alpha 2 agonist prejunctional a2 receptors inhibit release of NE, decreases vasoconstriction through CNS (a2 receptors normally produce vasoconstriction) ↓ BP Hypertension; opioid withdrawal; diarrhea Rebound HTN, hypotension, dry mouth, sedation, should not be abruptly discontinued
Enalapril
Vasotec ACE Inhibitor ↓ BP, afterload increase vasodilation, decrease aldosterone CHF, HTN, MI, angina Cough, orthostatic hypotension, hyperkalemia, not in pregnancy! Cough from failure to inactivate bradykinin
Losartan
Cozaar ARB ↓ BP, afterload increase vasodilation HTN, CHF Orthostatic hypotension; hyperkalemia; not in pregnancy!
Aliskiren
Renin inhibitor Inhibit peptidase activity of renin: Reduce Angiotensin II vasodilation HTN hyperkalemia Same efficacy as ACEs/ARBs, may have greater renin rebound
Verapamil
Calan, Isoptin Ca2+ blocker: diphenylalkylamine Bind to subunit of L-type channel, ↓ Ca2+ influx ↓ vascular tone; ↓ HR (countered by baroreceptor reflex) HTN (mild to severe); angina due to spasm Headache, flushing, constipation, premature labor, peripheral edema; NOT in CHF, heart block, or WPW
Nifedipine
Procardia Ca2+ blocker: dihydropyridine cardiosparing ↓ vascular tone, less heart effect Short or sustained release
Hydralazine
Apresoline Direct arterial relaxants ↓ BP, afterload possible NO donor, mechanism not fully understood HTN, CHF Headache, flushing, slow acetylators: lupus-like syndrome Depends on rate of liver acetylation
Minoxidil
Loniten/Rogaine K+ arterial relaxants ↓ BP, afterload HTN, baldness Headache, flushing, hypertrichosis
Omalizumab
Xolair Anti-IgE antibody binds circulating IgE Long-term control Asthma & Allergic Rhinitis SubQ every 2-4 weeks long-acting not all patients respond to treatment
Beclomethasone
Beclovent, Vaneril; Beconase, Vancenase Corticosteroid Inhibit synthesis of inflammatory mediators Increase number and responsiveness of B2 receptors (relaxation) Emergency or long-term Asthma, Rhinitis Inhalation (chronic) or IV (acute); Topical for Rhinitis Rapid systemic metabolism High lipid solubility; Promotes oropharyngeal candidiasis, dysphonia (hoarseness), suppression of adrenal axis in children, bone loss? First of its class
Flunisolide
AeroBid; Nasalide Asthma, Rhinitis
Corticosteroid
Ciclesonide
Corticosteroid
prodrug that is activated by esterases in mucosal cells

Asthma, Rhinitis
Budesonide
Pulmicort; Rhinocort
Corticosteroid Asthma in young children, Rhinitis Nebulizer
Methylprednisolone
Solu-medrol Emergency Asthma IV
Cromolyn
Intal; Nasalcrom, Crolom
Cromone Prevents release of mediators from mast cells Inhibits early and late responses; long-term Asthma: antigen, cold, & exercise induced; Rhinitis Inhalation, prior to exercise; nasal spray, optic solution 4-8 week trial Will not abort an acute attack
Nedocromil
Tilade; Alocril Cromone Inhibits mast cell activation & chemotaxis Long-term control; prior to exercise or exposure to known antigen 3-4 days to be efffective
Zileuton
Zyflo Anti-leukotriene 5-lipooxygenase inhibitor Long-term control; attenuates bronchospasm and inflammatory response Asthma, Rhinitis PO Short-acting ↑ liver enzymes; interferes w/ drug metabolism: warfarin, propranolol, theophylline
Montelukast
Singulair Leukotriene receptor antagonist Asthma, Rhinitis PO Long-acting excreted in bile
Ipratroprium
Atrovent Muscarinic antagonist bronchodilatation, reduce secretion long-term control Asthma, intolerant to B agonists; Rhinitis slow onset, long duration local irritation
Tiotropium
Spiriva Muscarinic & Cholinergic antagonist Chronic Bronchitis, emphysema long acting
Atropine
Cholinergic antagonist
Epinephrine
Primatine, Bronkaid α & β-adrenergic agonist inhibit mast cell release, increase mucociliary clearance, relax airway smooth muscle long-term control, PRN for acute symptoms Asthma Inhalation, SubQ (emergency) immediate onset, short duration Vasoconstriction, Cardiac stimulation, skeletal muscle tremor; refractoriness (counteracted w/ corticosteroid); mask progression of disease
Isoproterenol
Isuprel, Medihaler-Iso, Vapolso β- adrenergic agonist Asthma Inhalation, parenterally
Pirbuterol
Maxair beta 2 agonist Asthma Inhalation
Theophylline
Methylxanthine Block adenosine receptors, inhibit cAMP phosphodiesterase, alter translocation of intracellular Ca acute & long-term control Asthma, chronic bronchitis, emphysema IV, PO widely variable: disease, drug & diet dependent Headache, insomnia, anxiety, behavioral & learning problems, N&V, heartburn, ulcers, tremor, convulsions, arrhythmias; very narrow TI good oral bioavailability; crosses BBB, placenta
Diphenhydramine
Benadryl Ethanolamine "First Gen" H1 receptor antagonist, muscarinic receptor antagonist Rhinitis, sedation, motion sickness, common cold prophylaxis PO onset within 30 min., max effect at 1-2 hrs, duration 3-6hrs Sedation, anti-cholinergic action, hypersensitivity, tolerance, CNS stimulation in children Cross BBB & placenta
Chlorpheniramine
Tavist, Chlor-Trimeton Alkylamine
Hydroxyzine
"First Gen" H1 receptor antagonist, muscarinic receptor antagonist
Promethazine
"First Gen" H1 receptor antagonist, muscarinic receptor antagonist
Loratadine
Claritin "Second Gen" H1 receptor antagonist Longer half life Absorption altered with grapefruit juice; arrhythmias No crossing of the BBB, no sedation, no anticholinergic action
Desloratidine
"Second Gen" H1 receptor antagonist Longer half life Absorption altered with grapefruit juice; arrhythmias No crossing of the BBB, no sedation, no anticholinergic action
Fexofenadine
"Second Gen" H1 receptor antagonist Longer half life Absorption altered with grapefruit juice; arrhythmias No crossing of the BBB, no sedation, no anticholinergic action
Epinephrine
Adrenalin Cl alpha receptor agonist Vasoconstriction Rhinitis Topical rapid onset Few systemic; rebound congestion, rhinitis medicamentosa, tachyphylaxis
Phenylephrine
alpha receptor agonist Vasoconstriction Rhinitis Topical rapid onset Few systemic; rebound congestion, rhinitis medicamentosa, tachyphylaxis
Pseudoephedrine
Sudafed, Afrinol PO slow onset, longer acting dizziness, tremor, insomnia, irritability, palpitations, HTN less potential for dependence
Codeine
Antitussive Opiod analgesic decreases sensitivity of cough center antitussive action at doses lower than those required for analgesia
Dextromethorphan
Pertussin Antitussive
Opiod sterioisomer decreases sensitivity of cough center no analgesic or addictive effect
Guaifenesin
Expectorant stimulate secretory activity, reduce viscosity of mucus Triggers vagal reflex - near emetic doses required
Terpin hydrate
Expectorant
Iodides
Expectorant
Acetylcysteine
Mucomyst reduces sputum viscosity Inhalation
Chlorpromazine
Thorazine Aliphatic Phenothiazine (PTZ) Low Antagonist at dopamine D2 receptors, mostly in mesolimbic & mesocortical tracts (therapeutic effect); also antagonize histamine H1-receptors (CNS), muscarinic cholinergic receptors (PNS), and α-adrenergic receptors (PNS) Schizophrenia, Schizoaffective Disorder, Mania, Tourette's syndrome, antiemetic (except thioridazine), Delusional disorder; Depression w/ psychotic features, Borderline Personality Disorder, severe agitation/violence, delirium, dementia SE's: Agranulocytosis, cholestatic jaundice, photosensitivity Impotence/sexual dysfunction, orthostatic hypotension (α-adrenergic blockade); sedation, weight gain (histamine H1 blockade); anticholinergic crisis; seizures, hyperprolactinemia; withdrawal-like syndrome (nausea, vomiting, insomnia, headache); neuroleptic malignant syndrome Additive: CNS depressants (sedative- hypnotics, alcohol), Levodopa, anticholinergics; antacids decrease absorption, TCAs reduce blood levels, smoking increases metabolism; macrolide antibiotics Improves positive symptoms
Thioridazine
Mellaril Antagonist at dopamine D2 receptors, mostly in mesolimbic & mesocortical tracts (therapeutic effect); also antagonize histamine H1-receptors (CNS), muscarinic cholinergic receptors (PNS), and α-adrenergic receptors (PNS)
Piperidine PTZ Low SE's: ↑ Q-T interval, arrhythmia, priapism, retrograde ejaculation Cardiotoxic - sudden death; retinal pigmentation and blindness Hydroxyzine potentiates toxicity