Neuroleptic analgesia

Neuroleptic analgesia is so called because the combination of a major tranquilizer, a neuroleptic dmg, and a potent opiate produces an anesthetic state characterized by sedation, apathy, and mental detachment (see Psychopharmacological agents) (152). Iimovar [8067-59-2] a combination of droperidol [648-72-2], C22H22FN2O2, (19) and fentanyl (9) citrate, is used for procedures that do not require muscle relaxation. However, the onset of action is slow. 

The combination of droperidol and fentanyl is a fixed ratio preparation called innovar. Since droperidol is a neuroleptic substance, innovar is said to produce neurolept analgesia if combined with a more potent anesthetic, innovar produces neuroleptic anesthesia. A neuroleptic has adrenergic blocking as well as sedative, antiemetic, and anticonvulsant properties. Since innovar can cause extrapyramidal muscle movements, it is contraindicated in Parkinson s patients. 

Naloxone is being used to reverse the potentially lethal respiratory depression caused by neurolept analgesia or opioid overdose. Among other pharmacological effects, naloxone antagonizes the blood pressure drop in various forms of shock [29-32], reverses neonatal hypoxic apnoea [26], counteracts chronic idiopathic constipation [34], reduces the food intake in humans [35, 36] and shows beneficial effects in CNS injuries [37]. 

Phenothiazines are tricyclic compounds tliat have chemical and pharmacological properties in common with the tricyclic antidepressant drugs (Figure 34-13 see also previous section on Tricyclic Antidepressants). They are primarily used for their neuroleptic (behavior modifying) properties in the treatment of severe psychiatric iUness (psychoses and mania). In addition, phenothiazines are administered to control nausea and vomiting, for sedation, and for potentiation of analgesia and general anesthesia. ... 

It has been possible to produce a balanced type of anesthesia wherein low-potency N20 is combined with an opioid analgesic, usually the meperidine analog fentanyl (Fig. 5-10), or the more recent analogs sufentanil and alfentanil. When a butyrophenone-type neuroleptic (see later), particularly droperidol, is added, a state of neuroleptoanesthesia is produced where, without loss of consciousness, analgesia sufficient for surgery is achieved during which the patient still responds to commands.6... 

Some of these interactions may be potentially harmful (for example, the potentiation of opiates by MAO inhibitors) some interactions may help reduce the dose of, or frequency of dosing with, opiates so that there may be useful retardation of the development of tolerance and dependence. Other interactions may be less predictable but nevertheless important thus, both reserpine and chlorpromazine are neuroleptics and exert anti-psychotic activity in man, but whereas chlorpromazine may induce a useful potentiation of morphine analgesia in man (a property only partially explained on the basis of impaired hepatic... 

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