Sedation-induction

Inhibition of conditioned (but not unconditioned) avoidance behavior is one of the most predictive tests of antipsychotic action. Another is the inhibition of amphetamine- or apomorphine-induced stereotyped behavior. Other tests that may predict antipsychotic action are reduction of exploratory behavior without undue sedation, induction of a cataleptic state, inhibition of intracranial self-stimulation of reward areas, and prevention of apomorphine-induced vomiting. Most of these tests are difficult to relate to any model of clinical psychosis. 

Sedation Induction of a relaxed state, usually by a medication... 

To lessen anxiety and sedate the patient before surgery. Fhtients who are relaxed and sedated when anesthesia is given are easier to anesthetize (requiring a smaller dose of an induction anesthetic), as well as easier to maintain under anesthesia... 

Propofol (Diprivan) is used for induction and maintenance of anesthesia. It also may be used for sedation during diagnostic procedures and procedures that use a local anestiietic. This drug also is used for continuous sedation of intubated or respiratory-controlled patients in intensive care units. 

Midazolam (Versed), a short-acting benzodiazepine CNS depressant, is used as a preanesthetic drug to relieve anxiety for induction of anesthesia for conscious sedation before minor procedures, such as endoscopic procedures and to supplement nitrous oxide and oxygen for short surgical procedures. When the drug is used for induction anesthesia, the patient gradually loses consciousness during a period of 1 to 2 minutes. 

Preanesthetic drugs must be administered on time to produce their intended effects Failure to give the preanesthetic drug on time may result in events such as increased respiratory secretions caused by the irritating effect of anesthetic gasesand the need for an increased dose of the induction drug because the preanesthetic drug has not had time to sedate the patient. 

Although most of the medicinal chemistry effort in the H3 receptor field has been focused on the development of antagonists, there is some interest in agonists as well. Histamine H3 receptor agonists decrease the release of histamine in the central and peripheral nervous system and lead to a weakened histaminergic tone. In the brain, their effects will therefore be comparable to those of Hi receptor antagonists, with sedation and induction of sleep as a prominent observation. Indeed, H3 agonists such as the imidazoles... 

Vigilance for drug-drug interactions is required because of the greater number of medications prescribed to elderly patients and enhanced sensitivity to adverse effects. Pharmacokinetic interactions include metabolic enzyme induction or inhibition and protein binding displacement interactions (e.g., divalproex and warfarin). Pharmacodynamic interactions include additive sedation and cognitive toxicity, which increases risk of falls and other impairments. 

The history of this class of analgesics might have stopped there were it not for the manifold ancillary activities shown by that molecule. Although still one of the most widely used agents for treatment of severe pain, morphine is a drug that must be used with caution. Side effects include respiratory depression, induction of constipation, and sometimes marked sedation. The one property that most severely limits use of this drug is its propensity to induce physical dependence in patients subjected to more than casual exposure. 

Thiopental and methohexital belong to the barbiturates which, depending on dose, produce sedation, sleepiness, or anesthesia. Barbiturates lower the pain threshold and thereby facilitate defensive reflex movements they also depress the respiratory center. Barbiturates are frequently used for induction of anesthesia. 

IV Relief of severe pain pain of Ml used preoperatively to sedate the patient and allay apprehension, facilitate anesthesia induction, and reduce anesthetic dosage control postoperative pain relieve anxiety and reduce left ventricular work by reducing preload pressure treatment of dyspnea associated with acute left ventricular failure and pulmonary edema produce anesthesia for open-heart surgery. 

Sradycard/a Atropine is used in the suppression of vagally mediated bradycardias. Preoperative medication Atropine, scopolamine, hyoscyamine, and glycopyrrolate are used as preanesthetic medication to control bronchial, nasal, pharyngeal, and salivary secretions and to block cardiac vagal inhibitory reflexes during induction of anesthesia and intubation. Scopolamine is used for preanesthetic sedation and for obstetric amnesia. 

For the induction of sleep a higher dose and through that a more pronounced inhibition of the central nervous system is necessary than for the induction of sedation. These drugs have effects on the... 

Carbamazepine stimulates antidiuretic hormone activity and has been used for the treatment of neurohypophyseal diabetes insipidus. Carbamazepine induces microsomal enzymes and its metabolism is subject to auto-induction. Frequently occurring adverse effects are sedation, dry mouth, dizziness and gastrointestinal disturbances. Photosensitivity reactions, urticaria and Stevens-Johnson syndrome have been described. The elderly are more prone to mental confusion, cardiac abnormalities and problems due to inappropriate ADH secretion. 

In anesthesia drugs from several groups are used as premedication. Pre-anesthetic medication can decrease the anesthetic doses which otherwise would be required to induce anesthesia and so decrease the risk for adverse effects. Pre-anesthetic medication will increase the rate of induction of anesthesia and can reduce pre-operative pain and anxiety. Drugs include benzodiazepines for sedation and their muscle relaxant properties, opiates for pain relieve and anticholinergics or histamine Hi receptor antagonists against nausea and vomiting. Neuroleptics are also used as premedication for their antiemetic effects. 

Rapid recovery and its antiemetic properties make propofol anesthesia very popular as an induction agent for outpatient anesthesia. Propofol can also be used to supplement inhalational anesthesia in longer procedures. Both continuous infusion of propofol for conscious sedation and with opioids for the maintenance of anesthesia for cardiac surgery are acceptable techniques. 

Propoxyphene interacts with several drugs. The use of sedatives in combination with propoxyphene can be fatal. In addition, the metabolism of the drug is increased in smokers due to induction of liver enzymes. Thus, smokers may require a higher dose of the drug for pain relief. Propoxyphene enhances the effects of both warfarin and carbamazepine and may increase the toxicity associated with both drugs, such as bleeding and sedation, respectively. 

It may be used to produce light sedation and amnesia for unpleasant procedures by intravenous injection. It has also been used for induction and to supplement nitrous oxide anaesthesia. The benzodiazepines are further discussed in chapter Sedative and hypnotics in detail. 

It is indicated for preoperative sedation, conscious sedation prior to short diagnostic or endoscopic procedures, induction of general anaesthesia prior to administration of other anaesthetic agents. 

Recovery is sufficiently rapid with most intravenous drugs to permit their use for short ambulatory (outpatient) surgical procedures. In the case of propofol, recovery times are similar to those seen with sevoflurane and desflurane. Although most intravenous anesthetics lack antinociceptive (analgesic) properties, their potency is adequate for short superficial surgical procedures when combined with nitrous oxide or local anesthetics, or both. Adjunctive use of potent opioids (eg, fentanyl, sufentanil or remifentanil see Chapter 31) contributes to improved cardiovascular stability, enhanced sedation, and perioperative analgesia. However, opioid compounds also enhance the ventilatory depressant effects of the intravenous agents and increase postoperative emesis. Benzodiazepines (eg, midazolam, diazepam) have a slower onset and slower recovery than the barbiturates or propofol and are rarely used for induction of anesthesia. However, preanesthetic administration of benzodiazepines (eg, midazolam) can be used to provide anxiolysis, sedation, and amnesia when used as part of an inhalational, intravenous, or balanced anesthetic technique. 

Dioxopiperidines analogous to the barbiturates are also used for sedation and the induction of sleep. The 2,4-dioxo compounds pyrithyldione (125), introduced in 1936, and its saturated analogue, piperidione, proved to be toxic. They were replaced by the safer compound methyprylone (126). The 2,6-dioxo compound glutethimide (127) has been used... 

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