Severe pain in gynecologic cancer. Trial of pentazocine, morphine, and a placebo

Pentazocine

Published clinical studies and extensive experience has shown that pentazocine, the first of the practical agonist/antagonist analgesics, is a potent analgesic with wide application in clinical medicine. It has been shown to have a spectrum of pharmacological activity which has qualitative differences from pure opiate agonists and these have important implications in clinical medicine. Pentazocine can provide analgesia as great as the opiates including morphine and meperidine, but does not have the same effect on mood. It is, therefore, less effective than the opiates in those situations where an anxiolytic effect is desired. Conversely, it produces less CNS depression in particular with regard to respiratory depression and nausea and vomiting. It also does not have the same potential for producing hypotension. The parenteral administration of pentazocine produces rapid strong analgesia which is of less duration than with morphine or meperidine. The oral administration of pentazocine is less predictable with regard to response but in appropriate patients it is capable of providing a similar degree of analgesia to that achieved with parenteral pentazocine. The dependence liability of pentazocine is substantially less than that with the opiates, and where abuse of parenteral pentazocine alone has taken place, it has usually been in medical and paramedical personnel seeking a support for inadequate personalities. Though physical and psychic dependence to parenteral pentazocine is undoubtedly possible, its incidence is extremely low with regard to the extent of the therapeutic use of pentazocine.

Control of cancer pain with analgesics acting in the central nervous system

Systemic administration of opioids is one of the traditional, but by no means optimized therapeutic procedures in cancer pain. Besides the underlying pathophysiology, appropriate treatment has to take into account the psychodynamics and behavior of the patient as well as his life expectancy. In view of this, therapy with centrally acting analgesics can be considered after administration of analgesics with peripheral action first and then of psychoactive agents. Nefopam is a centrally (but not spinally) acting analgesic with a novel activity profile. Its advantages and disadvantages in the treatment of carcinoma pain are outlined. The opiate agonist-antagonist principle has the advantage of a lower dependence and tolerance potential. In addition, the preparations pentazocine, tilidine plus naloxone, and buprenorphine deviate from the morphine derivatives in various constituent effects. Their actions and side effects are outlined. The optimization of control of cancer pain is not possible without taking into account the time dimension. In 50 pain patients with advanced cancer, the following main errors were observed in previous treatment of pain syndromes: (1) too early parenteral administration in the course of the disease; (2) underdosage; (3) application intervals that were too long; and (4) use of analgesics as needed by the patient or on request and not according to a time schedule.

Clinical effects of pentazocine in hospitalized medical patients

Of 17,068 hospitalized medical patients monitored in a drug surveillance program, 616 (3.6 per cent) received pentazocine hydrochloride orally and 816 (4.8 per cent) received pentazocine lactate parenterally during one or more admissions. Unsatisfactory analgesic efficacy as judged by each patient's physician was nearly twice as frequent among recipients of pentazocine lactate as among recipients of parenteral morphine or meperidine. Adverse reactions were attributed to pentazocine hydrochloride in 18 recipients (2.9 per cent) and to pentazocine lactate in 37 recipients (4.5 per cent). Neuropsychiatric effects were the most common; they included hallucinations, bizarre feelings, disorientation, and agitation. These effects were dose dependent and frequently serious in nature. Minor gastro-intestinal effects were the second most common adverse reactions.