Ranitidine Anticholinergics

Ranitidine (Zantac 75) Antihistaminic—anticholinergic agents Cyclizine (Marezine)... 

Antagonists. Most of the so-called Hi-antihistamines also block other receptors, including M-cholinoceptors and D-receptors. Hi-antihistamines are used for the symptomatic relief of allergies (e.g., bamipine, chlorpheniramine, clemastine, dimethindene, mebhydroline pheniramine) as antiemetics (meclizine, dimenhydrinate, p. 330), as over-the-counter hypnotics (e.g., diphenhydramine, p. 222). Promethazine represents the transition to the neuroleptic phenothiazines (p. 236). Unwanted effects of most Hi-antihistamines are lassitude (impaired driving skills) and atropine-like reactions (e.g., dry mouth, constipation). At the usual therapeutic doses, astemizole, cetrizine, fexofenadine, and loratidine are practically devoid of sedative and anticholinergic effects. Hj-antihistamines (cimetidine, ranitidine, famotidine, nizatidine) inhibit gastric acid secretion, and thus are useful in the treatment of peptic ulcers. 

Geriatric Considerations-Summary Adjust dose based on creatinine clearance. Not effective in preventing NSAID-induced gastric ulceration and bleeding proton pump inhibitors should be used for this indication instead. Anticholinergic adverse effects have been observed in older adults taking ranitidine. 

Ketoconazole Antacids, anticholinergic drugs, cimetidine, ranitidine Decreased absorption. 

Procainamide (Pronestyl, Pronestyl SR, Procanbid) [Antiarrhythmic] WARNING Only use in life-treating arrhythmias hematologic tox can be severe Uses Supraventricular/ventricular arrhythmias Action Class 1A antiarrhythmic (Table VI-7) Dose Adults. Recurrent VF/pulseless VT 20 mg/min slow IV inf to a max of 17 mg/kg or until QRS T by 50% or dysrhythmia resolves Maint inf 4 mg/min (mix 1 gm in 250 mL NS to make 4 mg/mL use 60 gtt set—60 gtt/min = 4 mg) Peds. Loading dose 15-50 mg/kg IV/IO Caution [C, +] Contra Complete heart block, 2nd- or 3rd-degree heart block w/o pacemaker, torsades de pointes, SLE Disp Tabs caps 250, 500 mg SR tabs 500, 750, 1000 mg inj 100, 500 mg/mL SE 1 BP, lupus-like synd, GI upset, taste perversion, arrhythmias, tach, heart block, angioneurotic edema, blood dyscrasias Interactions T Effects W/ acetazolamide, amiodarone, cimetidine, ranitidine, trimethoprim T effects OF anticholinergics, antihypertensives i effects W/ procaine, EtOH EMS Monitor BP and ECG use caution to prevent rapid... 

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