The two antibiotics most commonly used are rifampicin and isoniazid. For active tuberculosis, it is often used with rifampicin, isoniazid, and either streptomycin or ethambutol. For active tuberculosis it is often given together with isoniazid, rifampicin, and pyrazinamide. This is seen with the simultaneous use of rifampin, isoniazid, and ketoconazole. These drugs include amiodarone, desipramine, isoniazid, ketoconazole, letrozole, methoxsalen, tranylcypromine. The doses of phenytoin may need to be adjusted when given with isoniazid. Both theophylline and isoniazid levels should be monitored. Valproate levels may increase when taken with isoniazid. Overdose of salicylates or isoniazid can also cause ketoacidosis. There are some cases of theophylline slowing down isoniazid elimination. Examples of such medications include lithium, hydantoin, isoniazid, glucocorticoids, iodides, bromides, and testosterone. With the introduction of isoniazid, a cure for tuberculosis was first considered possible. However, isoniazid and clonazepam have been used to treat dysmetria. Treatment of benzocaine with hydrazine leads to aminostimil - a compound related to isoniazid. The mode of antidepressant action of isoniazid is still unclear.