<p>In view of the potential for liver damage in long-term Dantrolene use, therapy should be stopped if benefits are not evident within 45 days. Patients should be cautioned against driving a motor vehicle or participating in hazardous occupations while taking Dantrolene. Caution should be exercised in the concomitant administration of tranquilizing agents. Dantrolene might possibly evoke a photosensitivity reaction; patients should be cautioned about exposure to sunlight while taking it. It is important to recognize that fatal and non-fatal liver disorders of an idiosyncratic or hypersensitivity type may occur with Dantrolene therapy. At the start of Dantrolene therapy, it is desirable to do liver function studies (SGOT, SGPT, alkaline phosphatase, total bilirubin) for a baseline or to establish whether there is preexisting liver disease. Liver function studies (e.g., SGOT or SGPT) should be performed at appropriate intervals during Dantrolene therapy. Some patients have revealed a return to normal laboratory values in the face of continued therapy while others have not. If symptoms compatible with hepatitis, accompanied by abnormalities in liver function tests or jaundice appear, Dantrolene should be discontinued. If caused by Dantrolene and detected early, the abnormalities in liver function characteristically have reverted to normal when the drug was discontinued. Dantrolene therapy has been reinstituted in a few patients who have developed clinical and/ or laboratory evidence of hepatocellular injury. If such reinstitution of therapy is done, it should be attempted only in patients who clearly need Dantrolene and only after previous symptoms and laboratory abnormalities have cleared. The patient should be hospitalized and the drug should be restarted in very small and gradually increasing doses. Laboratory monitoring should be frequent and the drug should be withdrawn immediately if there is any indication of recurrent liver involvement. Dantrolene should be used with particular caution in females and in patients over 35 years of age in view of apparent greater likelihood of drug-induced, potentially fatal, hepatocellular disease in these groups.<br />
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Dantrolene should be used with caution in patients with impaired pulmonary function, and in patients with severely impaired cardiac function due to myocardial disease. It should be used with caution in patients with a history of previous liver disease or dysfunction.</p>