CNS Depressant

• NREM


  Nonrapid eye movement (four stages)
• REM


  Rapid eye movement (dreaming)
• Sedative-hypnotics


  Commonly ordered for treatment of sleep disorders
• Sedation


  Diminishes physical and mental responses at lower dosages of certain CNS depressants but does not affect consciousness
• Short-acting hypnotics


  Useful in achieving sleep because they allow the patient to awaken early in the morning without experiencing lingering side effects
• Intermediate-acting hypnotics


  Useful for sustaining sleep; however, after using one, the patient may experience residual drowsiness, or hangover, in the morning
• Barbiturates


  Classified under the Controlled Substances Act as Schedule II for short-acting, Schedule III for intermediate-acting, and Schedule IV for long-acting hypnotics
• Long-acting barbiturates


  • PHENOBARBITAL and MEPHOBARBITAL, used to control seizures in epilepsy
• Intermediate-acting barbiturates


  • BUTABARBITAL, useful as sleep sustainers for maintaining long periods of sleep
• Short-acting barbiturate


  • SECOBARBITAL, may be used for procedure sedation
• Benzodiazepines


  Ordered as sedativehypnotics for inducing sleep, classified as Schedule IV according to the Controlled Substances Act
• Mechanism of benzodiazepines

  Increase the action of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) to the GABA receptors, reducing neuron excitability
• Benzodiazepines

  • Alprazolam – Treat anxiety and panic disorders
  • Estazolam – Treatment of insomnia
  • Lorazepam – Used for sedation induction and to reduce anxiety
  • Temazepam – Treatment for insomnia
  • Triazolam – Management of insomnia
• Pharmacokinetics of benzodiazepines

  Well absorbed through the GI mucosa, rapidly metabolized in the liver to active metabolites, intermediate half-life of 8 to 24 hours, highly protein bound
• Pharmacodynamics of benzodiazepines

  Used to treat insomnia by inducing and sustaining sleep, have a rapid onset of action and intermediate- to long-acting effects, lower initial dose recommended for older adults
• Nonbenzodiazepines


  Benzodiazepine-like psychoactive drugs used in the treatment of sleep problems, sometimes referred to as Z-drugs
• Pharmacokinetics of nonbenzodiazepines

  Zolpidem has a duration of action of 6 to 8 hours with a short half-life of 1.4 to 6.73 hours, metabolized in the liver to inactive metabolites
• Patient Teaching

  • Teach patients to use nonpharmacologic methods to induce sleep (taking a warm bath, listening to music, drinking warm fluids such as milk, avoiding drinks with caffeine after dinner)
  • Encourage patients to avoid alcohol, antidepressants, antipsychotics, and narcotic drugs while taking nonbenzodiazepines. Severe respiratory depression may occur when these drugs are combined
  • Advise patients to take nonbenzodiazepine before bedtime. Alprazolam takes effect within 15 to 30 minutes
  • Suggest that patients urinate before taking nonbenzodiazepines to prevent sleep disruption
  • Encourage patients to check with a health care provider about OTC sleeping aids
  • Warn the patient to use caution while driving as drowsiness may occur
• Melatonin Agonists


  This drug acts by selectively targeting melatonin receptors to regulate circadian rhythms in the treatment of insomnia. Ramelteon has not been shown to decrease REM sleep. This new drug has a half-life of 1 to 2.6 hours. Adverse effects of ramelteon include drowsiness, dizziness, fatigue, headache, nausea, and suicidal ideation
• Anesthetics


  • General
  • Local
• General anesthetics


  Depress the CNS, alleviate pain, and cause a loss of consciousness
• Balanced Anesthesia


  A combination of drugs frequently used in general anesthesia. It may include a hypnotic given the night before, premedication with an opioid analgesic or benzodiazepine plus an anticholinergic, a short-acting nonbarbiturate such as propofol, an inhaled gas, and a muscle relaxant given as needed. Balanced anesthesia minimizes cardiovascular problems, decreases the amount of general anesthetic needed, reduces possible postanesthesia nausea and vomiting, minimizes the disturbance of organ function, and decreases pain. Because the patient does not receive large doses of general anesthetics, fewer adverse reactions occur; and recovery is enhanced by allowing quicker mobility
• Inhalation Anesthetics


  Gas or volatile liquids administered as gas used to deliver general anesthesia. Inhalation anesthetics typically provide smooth induction
• Intravenous drugs


  • Ultrashort-acting Barbiturates: Methohexital sodium (Rapid onset, frequently used for induction), Thiamylal sodium (Rapid onset, used for induction of anesthesia and for electroshock therapy)
  • Benzodiazepines: Diazepam (Moderate to rapid onset, for induction of anesthesia, no analgesic effect), Midazolam (Rapid onset, for induction of anesthesia and for endoscopic procedures)
  • Others: Droperidol and fentanyl (Moderate to rapid onset, neuroleptic analgesic), Etomidate (Rapid onset, for short-term surgery), Ketamine hydrochloride (Rapid onset, used for short-term surgery or for induction of anesthesia), Propofol (Rapid onset, for induction of anesthesia, may be used for general anesthesia), Fospropofol (Rapid onset, for induction and maintenance of anesthesia)
• Topical Anesthetics


  Use of topical anesthetic agents is limited to mucous membranes, broken or unbroken skin surfaces, and burns. Topical anesthetics come in different forms: solutions, liquid sprays, ointments, creams, gels, and powders. Topical anesthetics decrease the sensitivity of nerve endings in the affected area
• Local Anesthetics


  Block pain at the site where the drug is administered by preventing conduction of nerve impulses. Local anesthetics are useful in dental procedures, suturing skin lacerations, short-term (minor) surgery at a localized area, blocking nerve impulses (nerve block) below the insertion of a spinal anesthetic, and diagnostic procedures such as lumbar puncture and thoracentesis. Local anesthetics may also be used to perform regional blocks—such as brachial plexus, axillary, femoral, or sciatic blocks—to provide analgesia for surgery of the upper or lower extremities
• Spinal Anesthesia


  Requires that a local anesthetic be injected into the subarachnoid space below the first lumbar space (L1) in adults and the third lumbar space (L3) in children. If the local anesthetic is given or spreads too high in the spinal column, the respiratory muscles could be affected, and respiratory distress or respiratory failure could result
• Types of Spinal Anesthesia

  • Nerve Block (Various sites of the spinal column can be used for local anesthetics)
  • Spinal Block (Results from the penetration of the anesthetic into the subarachnoid space, which is the space between the pia mater membrane and the arachnoid membrane)
  • Epidural Block (The placement of the local anesthetic in the epidural space just posterior to the spinal cord or the dura mater. The epidural space is located between the posterior longitudinal ligament on the anterior side and the ligamentum flavum posteriorly)
  • Caudal Block (An epidural block placed by administering a local anesthetic through the sacral hiatus)
  • Saddle block (Given at the lower end of the spinal column to block the perineal area)