Pharmacology Chapter 12 CNS Depressants and Muscle Relaxants

The primary adverse effects of muscle relaxants are an extension of their effects on the CNS and skeletal muscles.

Euphoria, lightheadedness, dizziness, drowsiness, fatigue, confusion, and muscle weakness are often experienced early in treatment.

The patient's chart notes the administration of dantrolene (Dantrium) immediately postoperatively. What does the nurse expect the patient has experienced?

Malignant hyperthermia

A patient is admitted to the emergency department after taking an overdose of a barbiturate 15 minutes prior to arrival. The nurse can anticipate that which drug will be prescribed?

activated charcoal

Upon discontinuance of a sedative-hypnotic drug, REM rebound can occur in which the patient has

an abnormally large amount of REM sleep, often leading to frequent and vivid dreams.

Some of the criteria by which to confirm a patient's therapeutic response to a CNS depressant include the following:

an increased ability to sleep at night, fewer awakenings, shorter sleep induction time, few adverse effects such as hangover effects, and an improved sense of well-being because of improved sleep.

Sedative-hypnotics can be classified chemically into three main groups:

barbiturates, benzodiazepines, and miscellaneous drugs.

Sedatives reduce nervousness, excitability, and irritability without causing sleep, but a sedative can

become a hypnotic if it is given in large enough doses.

Nursing interventions for barbiturates include

careful consideration of parenteral administration. You must have complete knowledge about incompatibilities with other drugs in solution as well as dilutional fluid incompatibilities.

Prolonged sedative-hypnotic use may reduce the cumulative amount of REM sleep; this is known as REM interference. This can result in

daytime fatigue because REM sleep provides a certain component of the "restfulness" of sleep.

Therapeutic effects related to muscle relaxants include

decreased spasticity, reduction of choreiform movements in Huntington's chorea, decreased rigidity in parkinsonian syndrome, and relief of pain from trigeminal neuralgia.

The sedative and hypnotic action of benzodiazepines is related to their ability to

depress activity in the CNS.

The sedative and hypnotic effects of barbiturates are

dose related, and they act by reducing the nerve impulses traveling to the cerebral cortex.

Barbiturates stimulate the action of

enzymes in the liver responsible for the metabolism or breakdown of many drugs. By stimulating the action of these enzymes, they cause many drugs to be metabolized more quickly, which usually shortens their duration of action.

A patient is admitted to the emergency department with a severe overdose of a benzodiazepine. The nurse immediately prepares to administer which antidote from the emergency drug cart?

flumazenil (Romazicon)

Sedatives and hypnotics are drugs that

have a calming effect or that depress the central nervous system (CNS).

Hypnotics cause sleep and

have a much more potent effect on the CNS than do sedatives.

Barbiturates were the standard drugs for treating

insomnia and producing sedation. Only a few are in use today due to the favorable safety profile and efficacy of the benzodiazepines

A patient asks the nurse about a new drug advertised on television. The patient wants to know if Ambien would be better for her to use than her current medication, Restoril, for periodic insomnia. The nurse's response is based on knowledge that zolpidem (Ambien) (Select all that apply.)

is less likely to cause grogginess in the morning. is a pregnancy category C medication. should be limited to 7 to 10 days of treatment.

Contraindications to the use of benzodiazepines include

known drug allergy, narrow-angle glaucoma, and pregnancy.

Contraindications to barbiturate use include

known drug allergy, pregnancy, significant respiratory difficulties, and severe kidney or liver disease.

Before giving any CNS depressant, it is always important to try

nonpharmacologic measures to induce sleep.

If medication therapy is indicated,

preventing respiratory depression and other problems associated with CNS depression is of prime importance, as is maintaining patient safety and preventing injury.

Sleep research involves study of the patterns of sleep, or what is sometimes referred to as sleep architecture, consisting of two basic elements that occur cyclically:

rapid eye movement (REM) sleep and non-rapid eye movement (non-REM) sleep.

The pharmacokinetics of each group of barbiturates lends specific characteristics to the drugs. Health care providers administering them must understand their life-threatening potential because too rapid an infusion may precipitate

respiratory or cardiac arrest.

Patients taking benzodiazepines and other CNS depressants experience

sedation and possible ataxia, thus the need for patient safety measures.

Benzodiazepines are commonly used for

sedation, relief of agitation or anxiety, treatment of anxiety-related depression, sleep induction, skeletal muscle relaxation, and treatment of acute seizure disorders.

Many drugs can act as either a sedative or a hypnotic, depending on dose and patient responsiveness, and for this reason are called

sedative-hypnotics.

An overdose of benzodiazepines may result in one or all of the following symptoms:

somnolence, confusion, coma, and diminished reflexes.

Phenobarbital is also used to treat

status epilepticus (prolonged uncontrolled seizures). In extreme cases, patients may be intentionally overdosed to the extent of causing therapeutic phenobarbital or pentobarbital coma.

Adverse effects of barbiturates relate to

the CNS and include drowsiness, lethargy, dizziness, hangover, and paradoxical restlessness or excitement.

Benzodiazepines have a relatively favorable adverse effect profile; however, they can be harmful if given in excessive doses or when mixed with alcohol. Adverse effects associated with their use usually involve... Commonly reported undesirable effects are...

the CNS. headache, drowsiness, paradoxical excitement or nervousness, dizziness or vertigo, cognitive impairment, and lethargy.

The toxicities and consequences of an overdose of muscle relaxants primarily involve

the CNS. There is no specific antidote (or reversal drug) for muscle relaxant overdoses.

A drug is classified as either a sedative or a hypnotic drug depending on

the degree to which it inhibits the transmission of nerve impulses to the CNS.

Benzodiazepines were once the most commonly prescribed sedative-hypnotic drugs; however,

the nonbenzodiazepine drugs are now more frequently prescribed.

Most muscle relaxants are known as centrally acting skeletal muscle relaxants because

their site of action is the CNS.

The muscle relaxants are a group of compounds that act predominantly

within the CNS to relieve pain associated with skeletal muscle spasms.

Barbiturates are

CNS depressants that act primarily on the brainstem in an area called the reticular formation.

An overdose of barbiturates produces

CNS depression ranging from sleep to profound coma and death.

Benzodiazepines and miscellaneous sedative-hypnotic drugs are prescription-only drugs, and they are designated as

Schedule IV controlled substances.

Barbiturates can produce many unwanted adverse effects.

They are physiologically habit forming and have a low therapeutic index.

Midazolam (Versed) has been ordered for a patient to be administered by injection 30 minutes prior to a colonoscopy. The nurse informs the patient that one of the most common side effects of this medication is which effect?

Amnesia

A nurse would monitor older adults who are prescribed a benzodiazepine for treatment of insomnia for which potential side effect?

Ataxia

During patient teaching, the nurse explains the difference between a sedative and hypnotic with which statement?

"Most drugs produce sedation at low doses and sleep, the hypnotic effect, at higher doses."

Muscle relaxants are most effective when they are used When taken with alcohol, other CNS depressants, or opioid analgesics,

- in conjunction with rest and physical therapy. - enhanced CNS depressant effects are seen.

Muscle relaxants are often used for the treatment of They result in

- muscle spasms, spasticity, and rigidity. - varying levels of decreased sensorium and CNS depression, depending on the drug, dosage, and route of administration. They are not used as sedative-hypnotic drugs.

Short-acting barbiturates include Intermediate-acting barbiturates include

- pentobarbital sodium and secobarbital. - amobarbital, aprobarbital, and butabarbital.

All barbiturates have the same sedative-hypnotic effects but differ in their They can be used as It is important to note that the use of barbiturates is

- potency, time to onset of action, and duration of action. - hypnotics, sedatives, and anticonvulsants and for anesthesia during surgical procedures. - no longer recommended for sleep induction.

Most sedative-hypnotic drugs suppress

REM sleep and should be used only for the recommended period of time. This time frame varies, depending on the specific drug used.

Which nursing diagnosis is appropriate for a patient who has received a sedative-hypnotic drug?

Risk for injury