Cimetidine Alcohol

Cimetidine. This agent, also known as Tagamet [51481-61-9] C qH N S (1) is soluble in alcohol, slightly soluble in water, very slightly soluble in chloroform, and insoluble in ether. The hydrochloride is freely soluble in water, soluble in alcohol, very slightly soluble in chloroform, and practically insoluble in ether. The method of preparation of cimetidine is available (2). 

There is an increase in anticholinergic effects when antihistamines are administered with the monamine oxidase inhibitors (MAOIs) and additive sedative effects if administered with central nervous system depressants (eg, narcotic analgesics or alcohol). When cimetidine and loratadine are administered together there is a risk for increased loratadine levels. 

There is a risk of acute renal failure when iodi-nated contrast material that is used for radiological studies is administered with metformin. Metformin therapy is stopped for 48 hours before and after radiological studies using iodinated material. Alcohol, amiloride, digoxin, morphine, procainamide, quini-dine, quinine ranitidine, triamterene, trimethoprim, vancomycin, cimetidine, and furosemide all increase the risk of hypoglycemia. There is an increased risk of lactic acidosis when metformin is administered with the glucocorticoids. 

For the purpose of this case study we will select Isopropyl alcohol as the crystallization solvent and assume that the NRTL-SAC solubility curve for Form A has been confirmed as reasonably accurate in the laboratory. If experimental solubility data is measured in IPA then it can be fitted to a more accurate (but non predictive) thermodynamic model such as NRTL or UNIQUAC at this point, taking care with analysis of the solid phase in equilibrium. As the activity coefficient model only relates to species in the liquid phase we can use the same model with each different set of AHm and Tm data to calculate the solubility of the other polymorphs of Cimetidine, as shown in Figure 21. True polymorphs only differ from each other in the solid phase and are otherwise chemically identical. 

Theophylline is a narrow therapeutic index drug with significant difference in bioavailability following oral administration. The half-life of the drug is increased by heart failure, cirrhosis and viral infections, in elderly patients, and by certain drugs, such as cimetidine, ciprofloxacin, oral contraceptives and fluvoxamine. The half-life is decreased in smokers, chronic alcoholism, and by certain drugs, such as phenytoin, rifampicin and carbamazepine. 

Drugs that may affect metformin include alcohol, cationic drugs, cimetidine, furosemide, iodinated contrast material, and nifedipine. 

Drugs that may affect HMG-CoA reductase inhibitors include alcohol, amiodarone, antacids, azole antifungals, bile acid sequestrants, cimetidine, cyclosporine, diltiazem, erythromycin, gemfibrozil, isradipine, nefazodone, niacin, nicotinic acid, omeprazole, phenytoin, propranolol, protease inhibitors, ranitidine, rifampin, St. John s wort, and verapamil. 

Drugs that affect all phosphodiesterase type 5 inhibitors include the following alcohol, amlodipine, angiotensin II receptor blockers, antacids, bendroflumethiazide, beta blockers, cimetidine, diuretics, enalaphl, metoprolol, nifedipine, rifampin, tacrolimus. 

Drugs that may affect antihistamines include aluminum/magnesium-containing acids, cimetidine, erythromycin, ketoconazole, MAO inhibitors, and rifamycins (eg, rifampin). Drugs that may be affected by antihistamines include alcohol and CNS depressants, beta-blockers, MAO inhibitors, metyrapone, nefazodone, selective serotonin reuptake inhibitors (SSRIs), and venlafaxine. 

Drugs that may affect benzodiazepines include alcohol, antacids, barbiturates, cimetidine, disulfiram, fluoxetine, isoniazid, ketoconazole, metoprolol, oral contraceptives, narcotics, probenecid, propoxyphene, propranolol, ranitidine, rifampin, scopolamine, theophylline, and valproic acid. 

Drugs that may affect benzodiazepines include alcohol/CNS depressants, cimetidine, oral contraceptives, disulfiram, isoniazid, probenecid, rifampin, smoking, theophyllines, and macrolides. 

Drugs that may affect metoclopramide include levodopa, anticholinergics, and narcotic analgesics. Drugs that may be affected by metoclopramide include alcohol, cimetidine, cyclosporine, digoxin, levodopa, MAO inhibitors, and succinylcholine. 

T Pancreatic insulin release Metformin Peripheral insulin sensitivity hepatic glucose output/production i intestinal glucose absorption Dose Ist-line (naive pts), 1.25/250 mg PO daily-bid 2nd-line, 2.5/500 mg or 5/500 mg bid (max 20/2000 mg) take w/ meals, slowly T dose hold before 48 h after ionic contrast media Caution [C, -] Contra SCr >1.4 mg/dL in females or >1.5 mg/dL in males hypoxemic conditions (sepsis, recent MI) alcoholism metabolic acidosis liver Dz Disp Tabs SE HA, hypoglycemia, lactic acidosis, anorexia, N/V, rash Additional Interactions T Effects W/ amiloride, ciprofloxacin cimetidine, digoxin, miconazole, morphine, nifedipine, procainamide, quinidine, quinine, ranitidine, triamterene,... 

Beta-blockers interact with a large number of other medications. The combination of beta-blockers with calcium antagonists should be avoided, given the risk for hypotension and cardiac arrhythmias. Cimetidine, hydralazine, and alcohol all increase blood levels of beta-blockers, whereas rifampicin decreases their concentrations. Beta-blockers may increase blood levels of phenothiazines and other neuroleptics, clonidine, phen-ytoin, anesthetics, lidocaine, epinephrine, monoamine oxidase inhibitors and other antidepressants, benzodiazepines, and thyroxine. Beta-blockers decrease the effects of insulin and oral hypoglycemic agents. Smoking, oral contraceptives, carbamazepine, and nonsteroidal anti-inflammatory analgesics decrease the effects of beta-blockers (Coffey, 1990). 

Estazolam potentiates the CNS depressant effects of phenothiazines, narcotics, antihistamines, MAOIs, barbiturates, alcohol, general anesthetics, and TCAs. Use with cimetidine, disulfiram, oral contraceptives, and isoniazid may diminish hepatic metabolism and result in increased plasma concentrations of estazolam and increased CNS depressant effects. Fleavy smoking (more than 20 cigarettes/day) accelerates estazolam s clearance. Theophylline antagonizes estazolam s pharmacological effects. 

Triazolam potentiates the CNS depressant effects of phenothiazines, narcotics, antihistamines, MAOIs, barbiturates, alcohol, general anesthetics, and antidepressants. Use with cimetidine and disulfiram may increase triazolam s plasma concentration. 

With the important exception of additive effects when combined with other CNS depressants, including alcohol, BZDs interact with very few drugs. Disulfiram (see the section The Alcoholic Patient in Chapter 14) and cimetidine may increase BZD blood levels, and diazepam may increase blood levels of digoxin and phenytoin. Antacids may reduce the clinical effects of clorazepate by hindering its biotransformation to desmethyidiazepam. Coadministration of a BZD and another drug known to induce seizures may possibly increase seizure risk, especially if the BZD is abruptly withdrawn. Furthermore, as noted earlier, important interactions have been reported among nefazodone, erythromycin, troleandomycin, and other macrolide antibiotics, as well as itraconazole. In each case, metabolism is inhibited, and triazolam levels can increase significantly. 

Taken with alcohol they potentiate the sedative effects and impairment of psychomotor performance. Hepatic enzyme induction by barbiturates or nicotine may reduce plasma levels. Cimetidine may increase levels by enzyme inhi bition. Some antipsychotic drugs may compete for similar metabolic pathways. 

Fosamprenavir PI2 1400 mg bid or 700 mg bid with ritonavir 100 bid or 1400 mg daily with ritonavir 100-200 mg daily. Adjust dose in hepatic insufficiency Separate dosing from antacids by 2 h. Avoid concurrent high-fat meals Diarrhea, nausea, vomiting, hypertriglyceridemia, rash, headache, perioral paresthesias, t liver enzymes See footnote 4 for contraindicated medications. Do not administer with lopinavir/ritonavir or in severe hepatic insufficiency. Also avoid cimetidine, disulfiram, metronidazole, vitamin E, ritonavir oral solution, and alcohol when using the oral solution... 

On the other hand, drugs may inhibit the metabolism of other drugs. For example, allopurinol (a xanthine oxidase inhibitor that inhibits the synthesis of uric acid) increases the effectiveness of anticoagulants by inhibiting their metabolism. Chloramphenicol (a potent inhibitor of microsomal protein synthesis) and cimetidine (an H2-receptor blocker used in acid-pepsin disease) have similar properties. In addition, drugs may compete with each other in metabolic reactions. In methyl alcohol (methanol) poisoning, ethyl alcohol may be given intravenously to avert methanol-induced blindness and minimize the severe acidosis. Ethyl alcohol competes with methyl alcohol for... 

Certain drugs can reduce the ability of the liver to clear benzodiazepines from the body. These include ulcer drugs, such as cimetidine (Tagamet), birth control pills, propranolol (used to treat hypertension, heart disorders, and migraines), and disulfuram (Antabuse), which is used for the treatment of alcoholism. 

Caffeine cannot sober a drunk or save someone who is lethargic or unconscious from an overdose of a sedating drug. However, because caffeine lowers stomach pH, it can affect the absorption of other substances. Other drugs such as oral contraceptives, cimetidine, disulfiram, and alcohol can delay the body s ability to rid itself of caffeine. 

Other medications that can slow down the metabolism of the liver, thereby causing a person to get a higher dose of methadone than they normally would, include Cimetidine, commonly used for upset stomachs, diazepam, a commonly used anti-anxiety medication, and fluvoxamine, a recently introduced antidepressant medication. Interestingly, alcohol, when used only occasionally, increases methadone levels as compared to decreasing methadone levels when it is used and abused on a chronic basis. 

Drugs and chemicals are known to cause activated interaction. The depressant action of opioid drugs is enhanced by drugs acting on the central nervous system (CNS) such as alcohol, anesthetics, anxiolytics, hypnotics, tricyclic antidepressants, and antipsychotics. Concomitant administration of opioid analgesics and monoamine oxidase inhibitors (MAOIs) should be avoided, or extra care should be taken if such a therapy is inevitable. Fatal reactions are reported when treated along with selegiline. Interactions also are reported with cyclizine, cimetidine, mexiletine, cisapride, metoclopramide, or domperidone. 

Cimetidine overdose should be treated with gastric lavage, emesis induction as an early measure, and should be followed by supportive and symptomatic treatment. Cimetidine interacts with antimuscarinics, antacids, sucralfate, antiarrhythmics, antiepileptics, antidiabetics, and alcohol.173... 

Biguanides This class of antidiabetics may cause acute poisoning with adverse effects such as acidosis and may be treated by supportive therapy. These drugs have therapeutic interactions with other antidiabetic drugs, alcohol, drugs that affect kidney function, and cimetidine. 

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