CH 12. CNS Depressants and Muscle Relaxants
Benzodiazepines: Sedative-Hypnotic Types
Long-acting ----diazepam (Valium), clonazepam (Klonopin) Intermediate-acting ----alprazolam (Xanax), lorazepam (Ativan), temazepam (Restoril) Short-acting ----midazolam (Versed), triazolam (Halcion) Ativan- for agitation or anxiety. Restoril- sleep. Halcion-first on market besides other barbs and benzos. Can still wake up and get to the bathroom safely. Short acting unlike others like valium. Worn off by morning. Others make you feel dopey
Barbiturates: Drug Effects
Low doses: sedative effects High doses: hypnotic effects (also lower respiratory rate) Notorious enzyme inducers ---Stimulate liver enzymes that cause metabolism or breakdown of many drugs ---Result in shortened duration of action
Sleep
Normal sleep is cyclic and repetitive A sleeping person is unaware of sensory stimuli within the immediate environment Sleep architecture ---Rapid eye movement (REM) sleep ----Non-REM sleep REM interference REM rebound
Benzodiazepines: Drug Effects
Calming effect on the CNS Useful in controlling agitation and anxiety Reduce excessive sensory stimulation, inducing sleep Induce skeletal muscle relaxation Reserve the rest for sleep. Most back injury are on some kind of muscle relaxant.
Barbiturates: Adverse Effects
Cardiovascular: vasodilation. hypotension CNS: drowsiness, lethargy, vertigo Respiratory: respiratory depression, cough GI: nausea, vomiting, diarrhea, constipation Hematologic: agranulocytosis, thrombocytopenia Other: hypersensitivity reactions, Stevens-Johnson syndrome
Benzodiazepines: Mechanism of Action
Depress CNS activity Affect hypothalamic, thalamic, and limbic systems of the brain Benzodiazepine receptors -----Gamma-aminobutyric acid (GABA) Do not suppress rapid eye movement (REM) sleep as much as barbiturates do Do not increase metabolism of other drugs
Muscle Relaxants: Adverse Effects
Extension of effects on CNS and skeletal muscles Euphoria Lightheadedness Dizziness Drowsiness Fatigue Muscle weakness, others should not drive since it is a sedative
Barbiturates
First introduced in 1903; were the standard drugs for insomnia and sedation Habit forming; low therapeutic index Only a handful commonly used today due in part to the safety and efficacy of benzodiazepines Occasionally used in psych patients
CNS Depressants: Hypnotics
Hypnotics Cause sleep Much more potent effect on CNS than sedatives A sedative can become a hypnotic if it is given in large enough doses
Benzodiazepines: Adverse Effects
*Mild and infrequent* Headache Drowsiness Dizziness Cognitive impairment Vertigo Lethargy Fall hazard for elderly persons "Hangover" effect/daytime sleepiness No hangover effect with halcion
Barbiturates: Drug Interactions
Additive effects ---Alcohol, antihistamines, benzodiazepines, opioids, tranquilizers Inhibited metabolism ---MAOIs will prolong effects of barbiturates Increased metabolism ---Reduces anticoagulant response, leading to possible clot formation
Barbiturates: Adverse Effects (cont'd)
Reduced REM sleep, resulting in: --Agitation --Inability to deal with normal stress
Muscle Relaxants: Indications
Relief of painful musculoskeletal conditions ---Muscle spasms ---Management of spasticity of severe chronic disorders (multiple sclerosis, cerebral palsy) Work best when used along with physical therapy
Benzodiazepines: Toxicity and Overdose
Somnolence- asleep and can't wake Confusion Coma Diminished reflexes Do not cause hypotension and respiratory depression unless taken with other CNS depressants Treatment symptomatic and supportive ----Flumazenil as an antidote
Barbiturates: Treatment of Overdose
Symptomatic and supportive Maintain adequate airway Assisted ventilation/oxygen therapy Fluids Pressor support Activated charcoal
Barbiturates: Four Categories
Ultrashort-acting ---Anesthesia for short surgical procedures, other uses Short-acting ---Sedation and control of convulsive conditions Intermediate-acting ---Sedation and control of convulsive conditions Long-acting ---Sleep induction, epileptic seizure prophylaxis
Herbal Products: Valerian
Used to relieve anxiety, restlessness, and sleep disorders May cause CNS depression, hepatotoxicity, nausea, vomiting, anorexia, restlessness, insomnia Many interactions, including with CNS depressants, MAOIs, phenytoin, warfarin, alcohol Contraindicated in cardiac and liver disease Patient should not operate heavy machinery during use
Herbal Products: Kava
Used to relieve anxiety, stress, and restlessness and to promote sleep May cause temporary yellow skin discoloration (extended, continued intake) and visual disturbances Potential interactions with alcohol, barbiturates, and psychoactive drugs Contraindicated in liver disease, alcoholism, other conditions Patient should not operate heavy machinery during use
When providing education to the patient on the use of a benzodiazepine medication, the nurse will include which information?
Using this medication may cause drowsiness the next day. Rationale: Benzodiazepines interfere with REM sleep and may cause a "hangover" effect or next-day drowsiness. They should not be used with alcohol, and persons taking these drugs should not drive.
Barbiturates have a low therapeutic index. This means
the effective, safe dosage range is narrow. Rationale: Drugs with a low therapeutic index have only a narrow dosage range within which the drug is effective; above that range, they are rapidly toxic. Barbiturates are habit forming, but this is not related to the therapeutic index.
An elderly patient taking multiple medications has a barbiturate added to his medication regimen. When administering a barbiturate to an elderly patient, the nurse should expect
to administer half of the usual dose of the barbiturate. Rationale: Barbiturates are associated with an increased incidence of falls when used in the elderly; therefore, the usual dose is reduced by half whenever possible. Because barbiturates stimulate the action of enzymes in the liver, drugs are usually broken down more quickly, sometimes requiring the dose to be increased. Patients taking barbiturates have decreased amounts of REM sleep and often experience paradoxical restlessness or excitement.
Common Muscle Relaxants
baclofen (Lioresal) *cyclobenzaprine (Flexeril)* dantrolene (Dantrium) *metaxalone (Skelaxin)* tizanidine (Zanaflex) *carisoprodol (Soma)* chlorzoxazone (Paraflex) *methocarbamol (Robaxin)*
Nursing Implications
-Before beginning therapy, obtain a thorough history regarding allergies, use of other medications, health history, and medical history -Obtain baseline vital signs and I&O, including supine and erect BPs -Assess for potential disorders or conditions that may be contraindications and for potential drug interactions -Give hypnotics 30 to 60 minutes before bedtime for maximum effectiveness in inducing sleep (depends on drug's onset) -Most benzodiazepines cause REM rebound and a tired feeling the next day; use with caution in the elderly -Instruct patients to avoid alcohol and other CNS depressants -Check with prescriber before taking any other medications, including over-the-counter medications -Rebound insomnia may occur for a few nights after a 3- to 4-week regimen has been discontinued
CNS Depressants: Benzodiazepines
-Formerly the most commonly prescribed sedative-hypnotic drugs -Nonbenzodiazepines currently more frequently prescribed -Favorable drug effect profiles, efficacy, and safety Classified as either: Sedative-hypnotic Anxiolytic (medication that relieves anxiety)
Common Barbiturates
-pentobarbital (Nembutol) -phenobarbital Don't mix wiith alcohol or opiods or benzos
Muscle Relaxants
Act to relieve pain associated with skeletal muscle spasms Majority are centrally acting ---CNS is the site of action ---Similar in structure and action to other CNS depressants Direct-acting ---Act directly on skeletal muscle ---Closely resemble GABA
Benzodiazepines: Interactions
Azole antifungals, verapamil, diltiazem, protease inhibitors, macrolide antibiotics, grapefruit juice CNS depressants (alcohol, opioids) olanzapine rifampin Don't give xanax with morphine or valium with
Which statement regarding muscle relaxants does the nurse identify as being accurate?
Baclofen (Lioresal) is available as an injectable form for use with an implantable pump device. Rationale: Baclofen (Lioresal) is sometimes used in an injectable form. Cyclobenzaprine (Flexeril) often results in deep sedation and sleepiness. Patients taking muscle relaxants are at risk to develop hypotension; therefore, they should be taught safety measures to prevent falls. Sedation and sleepiness are common side effects of muscle relaxants; however, a patient should not abruptly discontinue use of the medication. Safety procedures should be followed to prevent accidents and falls.
Barbiturates: Toxicity and Overdose
Overdose frequently leads to respiratory depression and subsequent respiratory arrest Overdose produces CNS depression (sleep to coma and death) Can be therapeutic ---Anesthesia induction ---Uncontrollable seizures: "phenobarbital coma"
Nursing Implications (cont'd)
Safety is important ---Keep side rails up or use bed alarms ---Do not permit smoking ---Assist patient with ambulation (especially the elderly) ---Keep call light within reach Monitor for adverse effects Monitor for therapeutic effects --Increased ability to sleep at night --Fewer awakenings --Shorter sleep-induction time --Few adverse effects, such as "hangover" effects --Improved sense of well-being because of improved sleep For muscle relaxants: Decreased spasticity, decreased rigidity
Benzodiazepines: Indications
Sedation Sleep induction Skeletal muscle relaxation Anxiety relief Anxiety-related depression Treatment of acute seizure disorders Treatment of alcohol withdrawal Agitation relief Balanced anesthesia Moderate/conscious sedation -Can contribute to depression if not on anti depressant -Pre-ops as diagnostic procedures. -Versa-amnesia drug
CNS Depressants (cont'd)
Sedative-hypnotics—dose dependent At low doses, calm the CNS without inducing sleep At high doses, calm the CNS to the point of causing sleep Classified into three main groups: -Barbiturates -Benzodiazepines -Miscellaneous drugs
Barbiturates: Indications
Sedatives Anticonvulsants Anesthesia for surgical procedures
CNS Depressants: Sedatives
Sedatives Drugs that have an inhibitory effect on the CNS to the degree that they reduce: Nervousness Excitability Irritability
CNS Depressants: Nonbenzodiazepine Hypnotics
Share many characteristics of benzodiazepines Used to treat insomnia Examples: zaleplon (Sonata), zolpidem (Ambien), eszoplicone (Lunesta), and ramelteon (Rozerem) Eszoplicone and extended-release zolpidem (Ambien CR) approved for long-term therapy Used in hospital, long term care. Safer than other drugs. Patients can get up and go to the bathroom. **lunesta the only one approved by FDA for long term use Ambien used most in hospital
Barbiturates: Mechanism of Action
Site of action ----Brainstem (reticular formation) By potentiating the action of GABA, nerve impulses traveling in the cerebral cortex are inhibited