H2-receptor antagonists dosing

H2-receptor antagonists (adjust all doses for renal impairment) ° Famotidine 20 mg IV or enterally ql2h... 

Ulcer prophylaxis H2-receptor antagonists Sucralfate Proton pump inhibitors Adjust dose in those with Rl decreased TAC absorption if Rl, caution aluminum content no Rl, caution hypophosphatemia... 

Administration of HA and its effect on sleep-wakefulness Local application of HA (5, 30 and 60 pg) in the TMN region of cats increased the latency to sleep, increased arousal, and reduced NREM sleep in a site-specific, dose-dependent manner. The highest dose produced the maximal effect, which lasted for 6 h. The HA-induced arousal was completely blocked when the cats were pretreated intraperitoneally with the Hi receptor antagonist mepyramine (Lin et at, 1986, 1988). In rats, intraventricular administration of HA blocked the increase in delta and theta activity (0-6 Hz) in the EEG induced by repeated low-frequency stimulation of the midbrain reticular formation. This effect was blocked if specific thalamic nuclei were lesioned (Tasaka et at, 1993) or by simultaneous administration of an Hi receptor antagonist, but not by an H2 receptor antagonist (Tasaka et at, 1989). Application of HA... 

Peds. GERD 10 mg/kg PO bid in doses, 150 mg bid max T in renal impair Caution [B, +] Contra H2-Receptor antagonist sensitivity Disp Caps, sol SE Dizziness, HA, constipation, D Interactions t Effects OF salicylates, EtOH X effects W/ antacids, tomato/mixed veg juice EMS Concurrent salicylate use can t risk of salicylate tox smoking t gastric acid secretion which can aggravate Dz Sxs OD May cause cholinergic-type effects (SLUDGE) activated charcoal may be effective... 

Histamine H2-receptor antagonists are well absorbed orally, although concurrent antacid therapy may reduce bioavailability by up to 30%. They are widely distributed in the body, crossing the blood-brain barrier and the placenta. Cimetidine, ranitidine and famotidine are extensively metabolised in the liver, and about one-third excreted unchanged in urine, while only one-third of nizatidine is metabolised (Table 11.1). Elimination half-life is increased up to tenfold in renal failure, and doses must be adjusted. 

Histamine H2-receptor antagonists are the mainstay of prevention of Mendelson s syndrome at present. Probably the best protection is afforded by a combination of H2-receptor blockade by ranitidine and a single oral dose of sodium citrate or bicarbonate. Because of its longer duration of action, and relative lack of enzyme inhibition, ranitidine is preferred to cimetidine for this purpose, although there is a latent period of 1-2 hours before it takes effect. Famotidine and nizatidine are probably equally effective in blocking acid secretion. 

Sustained hypochlorhydria due to drugs (proton pump inhibitors, high dose H2-receptor antagonists) ... 

Intracellular cyclic adenosine monophosphate (cAMP)-stimulated add secretion in the isolated guinea-pig gastric mucosa was not inhibited by administration of an H2-receptor antagonist, as expected, although H 83/69 (timoprazole) induced a dose-dependent inhibition. This was the first experimental evidence for a site of inhibitory action beyond the panel of stimulatory cell membrane receptors. Interestingly, it was found that the initial lead compound (CMN 131), had no inhibitory effect on dibutyryl-cAMP-stimulated acid secretion, nor was it an H2-receptor antagonist [9],... 

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