Caffeine interaction with other drugs

Acetaminophen can interact with other drugs, both in good and bad ways. For example, hospitals often combine acetaminophen with the narcotic pain reliever codeine (CoTylenol ) to treat more severe pain. Caffeine can increase the effectiveness of acetaminophen similarly to the way it does with aspirin. Brand names that use a combination of aspirin, caffeine, and acetaminophen include Excedrin and Vanquish . Combining these ingredients for their additive effects also reduces the dose needed for each one and thereby reduces the risk of side effects. However, there are a few drugs that should not be mixed with acetaminophen. These include anticonvulsants and alcohol, both of which increase the risk of liver damage. 

Studies of the interaction of DMHP with other drugs were performed with dogs. If such compounds as cocaine, caffeine, d-ampheta-mine, and nalorphine are used to antagonize the CNS depression produced by DMHP, they also can produce a marked Increase in toxicity and death. Death occurred during the depressed state that followed the stimulation induced by these agents. 

Caffeine, like theophylline, also undergoes extensive hepatic metabolism, principally by CYP1A2, and interacts with many drugs, but it has a wider therapeutic range. However, other xanthines may act differently (e.g. diprophylline does not undergo hepatic metabolism), so it should not be assumed that they all share common interactions. 

Because caffeine, nicotine, and alcohol are used by many people in some combination, knowing how each of these drugs interacts with the other two is important. 

The probable reason for the reduction in sedative effects with these drugs is that some of the components of tobacco smoke are enzyme inducers, which increase the rate at which the liver metabolises these benzodiazepines, thereby reducing their effects. The inference to be drawn is that smokers may possibly need larger doses than non-smokers to achieve the same therapeutic effects. Smoking also possibly reduces the drowsiness that the benzodiazepines and non-benzodiazepine hypnotics, such as zolpidem, can cause. However, one study suggested that caffeine intake, and others suggest age, may affect the response to benzodiazepines, so the picture is not altogether clear. Whether any of these interactions has much clinical relevance awaits assessment. 

Patients with cardiovascular disease (including hypertension), diabetes (risk of hyperglycemia), pregnancy (uterine contractions), prostatism, and anxiety disorders are among those who should not take ma huang at any dose. Drug-herb interactions occur with MAOIs (hypertensive crisis), phenoth-iazines (tachycardia, hypotension), (3-blockers (hypertension) and theophylline (increased CNS effects). Of course, caffeine and other stimulants have an additive effect. 

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