Anesthesiology in the 21st century: analgesic, sedative and anesthetic focusing

Fentanyl

Fentanyl, a potent lipid-soluble opioid which was first synthesized more than 40 years ago, is still the most popular opioid used in the perioperative period throughout the world. Fentanyl's introduction, versatility, and popularity have resulted in its use in many acute and chronic pain conditions and a multitude of novel delivery systems in the last two decades. In spite of the development of more potent, safer, faster onset, and both shorter and longer lasting alternative opioids, fentanyl remains the mainstay of anesthesiologists and Certified Registered Nurse Anesthetists in the perioperative period, and for many pain physicians throughout the world.

Novel delivery systems: oral transmucosal and intranasal transmucosal

During the past 2 decades, anesthesiologists have been provided with a number of new, potent opioid analgesics and sedative/hypnotics, as well as an increased understanding of the pharmacokinetic and pharmacodynamic principles that govern their action and disposition. These developments have suggested that the skin and the buccal and nasal mucous membranes may have use as alternate routes of analgesic and anesthetic drug delivery. A novel transmucosal delivery system for fentanyl has recently been developed by incorporating the drug into a dissolvable matrix on a stick called an "oralete." Oral transmucosal fentanyl citrate has been evaluated as a premedication in the pediatric population and as an analgesicfor acute postoperative and emergency room pain, procedural pain, and breakthrough cancer pain by using fentanyl. Increases in plasma fentanyl and onset of clinical effect are rapid (20-40 min) with this formulation. A potential advantage is the apparent ease of titration to a sedative or analgesic end point. This system may improve premedication, acute postoperative analgesia, and chronic pain therapy in various clinical settings. Delivery of opioids through the nasal mucosa also has been recently investigated. In one study, sufentanil was administered (1.5, 3.0, or 4.5 mu/kg) to 80 children ranging in age from 6 mo to 7yr. Easy separation from parents was achieved in 86% of the children 10 min following administration of the premedication. Unfortunately, 61% of the children cried after drug administration, and side effects included reduced ventilatory compliance (chest-wall rigidity) with higher doses (3.0 and 4.5 microg/kg). Nevertheless, nasal transmucosal drug delivery may have value, especially in frightened or uncooperative children.

Transnasal butorphanol: a new method for pain relief in post-cesarean section pain

This study was undertaken to evaluate the efficacy and the safety of transnasal butorphanol (TNB) compared to intravenous butorphanol (IVB) in 186 patients experiencing moderate to severe post-cesarean section pain. Patients were randomly assigned to five groups in a double-blind fashion: Group I (n = 37) received 2 mg IVB, Group II (n = 38) 2 mg TNB, Group III (n = 36) 1 mg TNB followed by a repeat dose of 1 mg TNB at 60 min, Group IV (n = 38) 0.5 mg TNB followed by a repeat dose of 0.5 mg at 60 min, and Group V (n = 37) received placebo. All administrations were double dummy. Pain intensity and relief were noted and the incidence of side effects was recorded. Remedication with the same study drug was allowed up to 72 h. Onset of analgesia was more rapid in the 2 mg IV group compared to the three TN groups: 5 min vs 15 min, respectively. However, the 2 mg and the 1-1 mg TN groups had a longer duration of analgesia, approximately 4.5 h, compared to 3.0 h for the 2 mg IV group (P less than 0.05). Somnolence was dose related and was the most frequent side effect, and was less frequent when the TN dose was divided into 2 doses administered 1 h apart. Multiple doses of TNB and IVB were safe and clinically acceptable up to 3 days at all doses studied. There were no incidences of nasal mucosa irritation, or cardiovascular or respiratory depression. It is concluded that transnasal butorphanol represents a safe and effective alternative to injectable butorphanol for post-cesarean section pain and offers a better and longer duration of analgesia compared to IV butorphanol. The optimum dose seems to be 2 mg TN butorphanol and it is tolerated better when divided into 1 mg increments, given 1 h apart.