Famotidine Antacids

HISTAMINE H2 ANTAGONISTS. The nurse administers ranitidine and oral cimetidine before or with meals and at bedtime Nizatidine and famotidine are given at bedtime or, if twice-a-day dosing is prescribed, in the morning and at bedtime. These drugp are usually given concurrently with an antacid to relieve the pain. In certain situations or disorders, cimetidine and ranitidine may also be given by intermittent IV infusion or direct IV injection. 

Intermittent, mild heartburn Lifestyle modifications plus patient-directed therapy Antacids Maalox or Mylanta 30 mL as needed or after meals and at bedtime Gaviscon 2 tabs after meals and at bedtime Calcium carbonate 500 mg, 2-4 tablets as needed and/or Nonprescription 11 receptor antagonists (taken up to twice daily) Cimetidine 200 mg Famotidine 10 mg Nizatidine 75 mg Ranitidine 75 mg or... 

Deravirdine (Rescnptor) [Antiretroviral/NNRTI] Uses HIV Infxn Action Nonnucleoside RT inhibitor Dose 400 mg PO tid Caution [C, ] CDC recommends HIV-infected mothers not to breast-feed (transmission risk) w/ renal/hepatic impair Contra Use w/ drugs dependent on CYP3A for clearance (Table VI-8) Disp Tabs SE Fat redistribution, immune reconstitution synd, HA, fatigue, rash, T transaminases, N/V/D Interactions T Effects W/ fluoxetine T effects OF benzodiazepines, cisapride, clarithromycin, dapsone, ergotamine, indinavir, lovastatin, midazolam, nifedipine, quinidine, ritonavir, simvastatin, terfena-dine, triazolam, warfarin effects W/ antacids, barbiturates, carbamazepine, cimetidine, famotidine, lansoprazole, nizatidine, phenobarbital, phenytoin, ranitidine, rifabutin, rifampin effects OF didanosine EMS Use of benzodiazepines and CCBs should be avoided may cause a widespread rash located on upper body and arms OD May cause an extension of nl SEs symptomatic and supportive Deferasirox (Exjade) [Iron Chelator] Uses Chronic iron overload d/t transfusion in pts >2 y Action Oral iron chelator Dose Initial 20 mg/kg... 

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. 

Diphenoxylate in high doses may produce dependence if coadministered with atropine. Diphenoxylate combined with thioridazine is associated with opioid withdrawal. Famotidine should be taken with care when coadministered with antacids, theophylline, and probenecid. Kaolin should not be administered with any other oral drug. Loperamide overdose should be treated with naloxone hydrochloride.174,175... 

Famotidine-OTC antacids and antifungal drugs (ketoconazole, itraconazole)... 

Antacids can reduce the effectiveness of famotidine, while famotidine itself can reduce the effectiveness of these antifungals... 

Antacids roughly halve the AUC of delavirdine, and the 112-receptor antagonists or proton pump inhibitors would be expected to interact similarly. Aluminium/magnesium antacids do not interact to a clinically relevant extent with efavirenz or nevirapine, and famotidine does not alter the absorption of efavirenz. 

The manufacturer notes that neither aluminium/magnesium hydroxide antacids nor famotidine had any effect on the absorption of efavirenz. No efavirenz dosage adjustment is expected to be necessary with these drugs. Other drugs that reduce gastric acidity are not expected to affect efavirenz absorption. ... 

The absorption of cimetidine, famotidine, nizatidine, and ranitidine may possibiy be reduced to some extent by antacids, but it seems doubtful if this significantly reduces their effects. Separating the dosages by 1 to 2 hours minimises any interaction. Roxa-tidine absorption appears not to be affected by antacids. Cimetidine appears not to interfere with the effectiveness of Gaviscon (sodium alginate compound). 

Mylanta 11 (aluminium/magnesium hydroxide mixture) 30 mL reduced the AUC and peak serum levels of famotidine by about a third when taken simultaneously, but no significant interaction occurred when the antacid was taken 2 hours after famotidine.Another study found that the peak serum levels of famotidine were reduced by about 25% by Mylanta II in 17 healthy subjects. ... 

Bar JiiN, Gatti G, Crema F, Perucca E. Impaired bioavailability of famotidine given con-cunenlly with a potent antacid. J Clin Pharmacol (1989) 29,670-2. 

Tiqy-VisichMA Tarzian SK, Schwartz S, Lin JH, Hessey GA Kanovsky SM, Chremos AN. BioavaUability of (X dl famotidine when administered with antacid or food J Clin Pharmacol (198 26,555. 

Schwartz Jl, Yeh KC, Bolc ese J, Laskin OL, Patterson PM, Shamblen EC, Han R, Lasseter KC. Lack of effect of chewable antacid on famotidine pharmacodynamics and iharmacoki-netics. Pharmacodterapy (1994) 14,375. 

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