Nalbuphine and butorphanol, like pentazocine, play a limited role in the treatment of chronic pain. Neither is available for oral use. Their propensity to cause psychotomimetic (actions mimicking the symptoms of psychosis) effects is less than that of pentazocine. Nalbuphine does not affect the heart or increase blood pressure, in contrast to pentazocine and butorphanol. A benefit of all three medications is that they exhibit a ceiling effect for respiratory depression