Clinical pharmacy
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The anatomy and physiology of the epidural space and the mechanism of action, sites of action, and pharmacokinetics of analgesics administered by continuous epidural infusion are reviewed, and the efficacy, adverse effects, and postoperative indications for use of analgesics administered by this route are discussed. Narcotics selectively block pain conduction by occupying specific opiate receptors in the spinal cord. Local anesthetics provide analgesia by axonal membrane blockade; they also can produce nonselective sympathetic and somatic (sensory and motor) blockade in addition to analgesia. ⋯ Adverse effects of epidurally administered local anesthetics include urinary retention, hypotension, numbness, motor weakness, tachyphylaxis, and, rarely, systemic toxicity. The cost of epidurally administered drugs is substantially higher than that for i.m. or i.v. narcotic analgesia, but this cost may be offset by other benefits such as a shorter hospital stay. Current studies suggest superior analgesia for the majority of surgical procedures with continuous epidural analgesia infusions compared with more traditional methods of providing analgesia.
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The pathophysiology, assessment, and pharmacologic management of acute pain in infants and children are reviewed, and the mechanism of action, pharmacokinetics, clinical efficacy, adverse effects, and dosages of opioid analgesics, nonopioid analgesics, and local anesthetics used for regional blocks are discussed. The pathophysiology of pain and the physiologic rationale for treatment of pain are similar in children and adults. Severe pain can be controlled by i.v. or epidural administration of opioid analgesics. ⋯ Topical application of local anesthetics is effective for many minor procedures. A variety of pain management techniques are available for the management of acute pain in pediatric patients. The development of drugs having fewer adverse effects and noninvasive administration techniques will be important research priorities in the coming years.
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The pharmacokinetics, pharmacodynamics, and clinical uses of fentanyl, sufentanil, and alfentanil are reviewed. The fentanyl derivatives have reduced or eliminated many of the disadvantages of opioid anesthetics, such as incomplete amnesia and undesirable hemodynamic responses to surgery. Fentanyl is 50-100 times as potent as morphine and was the first of the three to be marketed. ⋯ Fentanyl has been formulated as a transdermal patch that seems to provide the same degree of analgesia as a continuous i.v. infusion. Fentanyl has also been formulated as an investigational lozenge that has shown advantages as a preoperative sedative in children. As more is learned about these agents, their perioperative uses for anesthesia, analgesia, and sedation will continue to be refined.
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The incidence, pathogenesis, staging, and treatment of endometriosis are reviewed, with an emphasis on pharmacologic management of this condition. Endometriosis--the presence of ectopic endometrial tissue--can be found in 15-25% of infertile women and may be found in 1-5% of all women between menarche and menopause. Although the pathogenesis of endometriosis is uncertain, the most tenable etiologic theory is a combination of celomic metaplasia and retrograde menstruation. ⋯ The most common adverse effect associated with nafarelin therapy is hot flashes. The GnRH agonist nafarelin is as effective as danazol or oral contraceptives for the treatment of endometriosis and causes fewer adverse reactions. GnRH agonists may replace danazol as the treatment of choice in patients with endometriosis.