Topical anesthesia for endoscopy; evaluation of prilocaine (Citanest), a new local anesthetic.

OPICAL ANESTHESIA REPRESENTS A T c o m m o d y used anesthetic technique for a variety of endoscopic procedures.'4 In general, local anesthesia for endoscopy is a safe and effective procedure.g However, it has been shown that certain local anesthetics, such as tetracaine, are rapidly absorbed from the mucous membranes of the respiratory tract and can lead to severe toxic effects in man.' Thus, it would be desirable to use a local anesthetic topically in the tracheobronchial tree which combines both anesthetic effectiveness and low s9emic toxicity in order to avoid any systemic reactions which might occur due to rapid absorption from the mucous membranes of the respiratory tract. During the past ten years, we have used 1 or 2 per cent lidocaine (Xylocainet) as the local anesthetic agent of choice for endoscopic procedures.' Although we have not observed any serious adverse effects with lidocaine, a series of studies was initiated with a new local angthetic agent, prilocaine (Citanestt), whose potency is comparable to that of lidocaine, but whose toxicity is approximately 50 per cent less than that of lid~caine.'~ Although a great number of clinical studies"" have confirmed the earlier pharmacologic reports that prilocaine is comparable in potency to lidocaine, but considerably less toxic, little data is available on the topical anesthetic efficacy of prilocaine in man. To date, Thomton" and TelivuoU have published data in a limited number of patients which indicate that ~rilocaine in a concentration of -