[Two cases of chronic respiratory failure in intravenous methylphenidate (Ritalin) abusers].

Marked obstructive ventilatory impairment and diffusion disturbance were noted in two intravenous methylphenidate (Ritalin) abusers. In one patient, chest radiogram demonstrated pulmonary emphysema accompanied by bullae and atelectasis, and spontaneous pneumothorax was also present. The primary finding in the other patient was interstitial shadows. Both patients began to note dyspnea during exertion after about 10 years of use. Since radiography also disclosed pulmonary emphysema in an ex-companion of Ritalin abuse, and since the onset was at relatively young ages, these pulmonary disorders are considered to have been a result of intravenous Ritalin abuse. Intravenous drug abuse should be considered in patients with precocious emphysema or obstructive ventilatory impairment accompanied by diffusion disturbance.