Drug failure interactions with other drugs

Propranolol 13- Adrenoceptor blockade Direct membrane effects (sodium channel block) and prolongation of action potential duration slows SA node automaticity and AV nodal conduction velocity Atrial arrhythmias and prevention of recurrent infarction and sudden death Oral, parenteral duration 4-6 h Toxicity Asthma, AV blockade, acute heart failure Interactions With other cardiac depressants and hypotensive drugs... 

Despite its popularity, limited information is available on the safety, interactions with other drugs, and the mechanisms of interaction of silymarin and miUc thistle. Patients who want to use this plant should be advised about the potential for interactions in order to reduce therapeutic failure or increased toxicity of conventional drug therapies. 

Enzymes are one major target for drugs. Receptors are another. Drugs which interact with receptors are amongst the most important in medicine and provide treatment for ailments such as pain, depression, Parkinson s disease, psychosis, heart failure, asthma, and many other problems. 

Some chemical exposures may be hepatic enzyme inducers/inhibitors, altering the effects of drugs like warfarin. Some foods such as mono-amines, will cause reactions in patients given MAOIs grapefruit juice may interact with terfenadine and some other drugs. New diseases may cause problems heart failure causing reduced liver blood flow can reduce the metabolism of drugs like warfarin. 

Phenylbutazone (Butazolidin) is metabolized to oxy-phenbutazone (Phlogistol), and both compounds have all of the activities associated with the NSAIDs. Their use is accompanied by serious adverse reactions, such as anemia, nephritis, renal failure or necrosis, and liver damage. Because of their toxicity, they are prescribed only for the treatment of pain associated with gout or phlebitis or as a last resort for other painful inflammatory diseases resistant to newer and less toxic treatments. Interactions with a large number of other drugs... 

Drug interactions No formal drug interaction studies of darbepoetin with other medications commonly used in chronic renal failure patients have been performed. 

As noted earlier, lithium is contraindicated in patients with unstable congestive heart failure or the sick sinus node syndrome ( 307, 328). In older patients or those with prior cardiac histories, a pretreatment ECG should be obtained. Except for the potential adverse interactions with diuretics, the concomitant use of other cardiac drugs is generally safe. Because verapamil may lower serum levels of lithium, however, more careful monitoring may be required to assure continued therapeutic effects (329). Some data also indicate that verapamil may predispose to lithium neurotoxicity. Conversely, increased lithium levels leading to toxicity has occurred with methyidopa and enalapril. When antihypertensive therapy is necessary, b-blockers are a reasonable choice when lithium is coadministered. 

Verapamil, diltiazem Nonselective block of L-type calcium channels in vessels and heart Reduced vascular resistance, cardiac rate, and cardiac force results in decreased oxygen demand Prophylaxis of angina, hypertension, others Oral, IV, duration 4-8 h Toxicity Atrioventricular block, acute heart failure constipation, edema Interactions Additive with other cardiac depressants and hypotensive drugs... 

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