Misc Agents Flashcards
Diphenhydramine, Promethazine, Meclizine, Hydroxyzine, Doxylamine
First Generation H1 Histamine Receptor Blockers
Histamine normally contracts smooth muscle, causes pruritis, and increases capillary permeability. Blocking H1 receptors causes bronchodilation, decreased pruritis, decreased PVR, decreased GI tract motility, and decreased rash formation. Some antagonistic effects on ACh and a-adrenergic receptors (causes side effects).
Prevention and Rx of allergic rhinitis, urticaria, allergic reactions, motion sickness. Promethazine primarily used as an antiemetic, Meclizine Rx vertigo and motion sickness. SE: sedation, anticholinergic effects (dry mouth, blurry vision), tremors.
Fexofenadine, Loratadine, Cetirizine
Second Generation H1 Histamine Receptor Blockers
Histamine normally contracts smooth muscle, causes pruritis, and increases capillary permeability. Blocking H1 receptors causes bronchodilation, decreased pruritis, decreased PVR, decreased GI tract motility, and decreased rash formation.
Rx of allergic rhinitis and other seasonal allergy symptoms. SE: mild sedation, GI upset. Cross the BBB less readily than G1, leading to less sedation. Also do not cross-react with ACh/a-adrenergic receptors like G1, so fewer side effects.
Ethanol
CNS Depressant.
Enhances flow of Cl- through GABA-associated channels, potentiating the inhibitory effects of GABA on the brain.
Rx of ethylene glycol and methanol overdose (create toxic metabolites) since compete for same metabolic enzymes, decreasing their metabolism and formation of toxic metabolites.
SE: orthostatic hypotension, CNS depression (dizziness, sedation, impaired judgement), GI inflammation (gastritis, pancreatitis, hepatitis), teratogen (fetal alcohol syndrome). Long term abuse leads to alcoholic liver disease and cirrhosis, portal HTN, renal failure, encephalopathhy. Treat dependence with Disulfiram, causes n/v.
Disulfiram
Alcohol Metabolism Agent.
EtOH is metabolized in the liver by 2 oxidation rxns with NAD+ as the limiting reagent. Alcohol dehydrogenase converts EtOH to acetaldehyde, then acetaldehyde dehydrogenase converts that to acetate.
Inhibits acetaldehyde dehydrogenase, causing an accumulation of acetaldehyde, leading to nausea and vomiting. This unpleasantness acts as negative feedback for drinking alcohol.
Theophylline
Phosphodiesterase Inhibitor.
Inhibits phosphodiesterase (breaks down cAMP), leading to increased cAMP then bronchial smooth muscle relaxation (bronchodilation).
Rx of acute and chronic asthma. SE: GI upset, anxiety, arrhythmia, seizures. Narrow therapeutic index, SE can be caused by overmedication. Metabolized by cytochrome P-450.
Iron
Toxin.
MOA: Forms reactive oxygen species.
Signs: Abdominal pain, bloody diarrhea, unconsciousness.
Antidote: Deferoxamine
Lead
Toxin.
MOA: Interferes with heme synthesis, alters cell membrane structure.
Signs: Abdominal pain, neuropathy, anemia, basophilic stippling of erythocytes.
Antidote: Calcium EDTA, Dimercaprol, Penicillamine
Arsenic
Toxin.
MOA: Inhibits several enzyme processes, especially in oxidative phosphorylation.
Signs: Garlic odor on breath, bloody diarrhea, hair loss, neuropathy.
Antidote: Dimercaprol, Penicillamine
Cyanide
Toxin.
MOA: Blocks a cytochrome complex in the electron complex chain.
Signs: HA, GI upset, seizures, coma.
Antidote: Sodium thiosulfate, Nitrites.
Carbon Monoxide
Toxin.
MOA: Binds to hemoglobin, reducing oxygen binding and tissue delivery.
Signs: HA, GI upset, seizures, coma.
Antidote: 100% oxygen.
Cytochrome P-450
Induce: Barbituates, Phenytoin, Carbamazepine, Rifampin, Quinidine, St. Johns Wart, Griseofulvin, Chronic alcohol use. Others: Metronidazole, TMP-SMX, Nevirapine, Zafirlukast, SSRIs.
Impair: Cimetidine, Isoniazid, Fluoxetine, Erythromycin (Macrolides), Ketoconazole, Ritonavir, Grapefruit juice, Aminodarone, Acute alcohol abuse, Ciprofloxacin, Sulfonamides. Others: Cholestyramine.
Sensitive: Warfarin, Phenytoin, Tricyclic antidepressants, Theophylline, Carbamazepine, Cyclosporine, Beta-blockers, Calcium Channel Blockers, Haloperidol, Benzodiazepines, Oral contraceptives.
