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Questions and Answers
What is the primary use of muscle relaxants?
What is the primary use of muscle relaxants?
Which of the following conditions might muscle relaxants be prescribed for?
Which of the following conditions might muscle relaxants be prescribed for?
How do centrally-acting muscle relaxants primarily work?
How do centrally-acting muscle relaxants primarily work?
What is a common adverse effect of centrally-acting muscle relaxants?
What is a common adverse effect of centrally-acting muscle relaxants?
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Which of the following drugs is primarily used as a peripherally-acting muscle relaxant?
Which of the following drugs is primarily used as a peripherally-acting muscle relaxant?
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What is the most significant concern regarding the use of high therapeutic doses of dantrolene sodium?
What is the most significant concern regarding the use of high therapeutic doses of dantrolene sodium?
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Which drug has the longest duration of action among centrally-acting muscle relaxants?
Which drug has the longest duration of action among centrally-acting muscle relaxants?
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What is a potential interaction concern with cyclobenzaprine?
What is a potential interaction concern with cyclobenzaprine?
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What is the primary mechanism of action of dantrolene?
What is the primary mechanism of action of dantrolene?
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In which of the following conditions is dantrolene especially effective for managing spasticity?
In which of the following conditions is dantrolene especially effective for managing spasticity?
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What is the potential effect of combining dantrolene with other CNS depressants?
What is the potential effect of combining dantrolene with other CNS depressants?
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What is the typical metabolism route for dantrolene in healthy adults?
What is the typical metabolism route for dantrolene in healthy adults?
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Which class of drugs primarily acts as sedatives and hypnotics?
Which class of drugs primarily acts as sedatives and hypnotics?
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Which of the following statements is true regarding the pharmacodynamics of benzodiazepines?
Which of the following statements is true regarding the pharmacodynamics of benzodiazepines?
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What adverse effect can occur with the use of dantrolene when given with estrogen?
What adverse effect can occur with the use of dantrolene when given with estrogen?
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Which benzodiazepine is NOT classified primarily for insomnia treatment?
Which benzodiazepine is NOT classified primarily for insomnia treatment?
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What is the primary effect of low doses of secobarbital sodium?
What is the primary effect of low doses of secobarbital sodium?
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What is a significant risk associated with high doses of barbiturates?
What is a significant risk associated with high doses of barbiturates?
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Which of the following is a characteristic of nonbenzodiazepines-nonbarbiturates used in treating insomnia?
Which of the following is a characteristic of nonbenzodiazepines-nonbarbiturates used in treating insomnia?
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Which pharmacokinetic characteristic is common among nonbenzodiazepines-nonbarbiturates?
Which pharmacokinetic characteristic is common among nonbenzodiazepines-nonbarbiturates?
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What is a benefit of buspirone compared to other anxiolytics?
What is a benefit of buspirone compared to other anxiolytics?
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What is the primary clinical indication for the use of benzodiazepines?
What is the primary clinical indication for the use of benzodiazepines?
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What characteristic defines the pharmacodynamics of buspirone?
What characteristic defines the pharmacodynamics of buspirone?
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What is a significant consequence of prolonged use of barbiturates?
What is a significant consequence of prolonged use of barbiturates?
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Study Notes
Muscle Relaxants
- Relieve musculoskeletal pain and spasm, and severe musculoskeletal spasticity
- Used to treat acute, painful musculoskeletal conditions and muscle spasticity associated with Multiple Sclerosis (MS), cerebral palsy, stroke, and spinal cord injuries
- Two main classes: centrally-acting and peripherally-acting
Centrally-Acting Muscle Relaxants
- Act on the central nervous system
- Used to treat acute spasms caused by anxiety, inflammation, pain and trauma
- Examples: baclofen, carisoprodol, chlorphenesin, chlorzoxazone, cyclobenzaprine, metaxalone, methocarbamol, orphenadrine, tizanidine
Centrally-Acting Muscle Relaxants Pharmacokinetics
- Absorbed in the gastrointestinal tract (GIT)
- Widely distributed
- Metabolized in the liver and excreted through the kidneys
- Onset: oral is 30 minutes to 1 hour; duration varies from 4 to 6 hours
- Cyclobenzaprine has the longest duration of 12 to 25 hours
Centrally-Acting Muscle Relaxants Pharmacodynamics
- Do not relax skeletal muscles directly or depress neuronal conduction, neuromuscular transmission, or muscle excitability
- Depress the CNS
- Treat acute, painful musculoskeletal conditions
- Usually prescribed along with rest and physical therapy
Centrally-Acting Muscle Relaxants Drug Interactions
- Interact with other CNS depressants causing increased sedation, impaired motor function and respiratory depression
- Cyclobenzaprine interacts with MAOIs and can result in high body temperature, excitation and seizures
- Methocarbamol can antagonize the cholinergic effects of the anticholinesterase drugs used to treat myasthenia gravis
Centrally-Acting Muscle Relaxants Adverse Reactions
- Most frequently seen adverse effects relate to associated CNS depression, GI disturbances linked to CNS depression of the parasympathetic reflexes, hypotension and arrhythmias, urinary frequency, enuresis, and feelings of urinary urgency
- Chlorzoxazone may discolor the urine, becoming orange to purplish-red when metabolized and excreted
- Tizanidine has been associated with liver toxicity and hypotension in some patients
Peripherally-Acting Muscle Relaxants
- Most common is dantrolene sodium
- Major effect is on the muscles
- High therapeutic doses are toxic to the liver
Peripherally-Acting Muscle Relaxants Pharmacokinetics
- Peak is 5 hours after ingestion
- Absorbed slowly in the GIT; highly plasma bound
- Metabolized in the liver with a half life of 4 to 8 hours and excreted in the urine
- Half life for healthy adults is 9 hours; may be prolonged for patients with liver dysfunction
Peripherally-Acting Muscle Relaxants Pharmacodynamics
- Dantrolene works by acting on the muscle
- Interferes with calcium ion release from the sarcoplasmic reticulum and weakens the force of contraction
Peripherally-Acting Muscle Relaxants Pharmacotherapeutics
- Helps manage spasticity especially in patients with cerebral palsy, MS, SCI, and stroke
- Used to treat and prevent malignant hyperthermia
Peripherally-Acting Muscle Relaxants Drug Interactions
- Simultaneous use of dantrolene and other CNS depressants, such as anxiolytics, sedatives, and hypnotics, can increase CNS depression
- If given with estrogen, may lead to increased risk of liver toxicity
Sedatives and Hypnotics
- Sedatives reduce activity or excitement
- When given in large doses, sedatives are considered hypnotics
- Three main classes of synthetic drugs used as sedatives and hypnotics are: benzodiazepines, barbiturates, and nonbenzodiazepine-nonbarbiturate drugs
Benzodiazepines
- Minor tranquilizer; anxiolytic
- Therapeutic effects include daytime sedation, sedation before anesthesia, sleep inducement, relief on anxiety and tension, skeletal muscle relaxation, and anticonvulsant activity
- Examples: estazolam, flurazepam, lorazepam, quazepam, temazepam, triazolam
Benzodiazepines Pharmacokinetics
- Absorbed well from the GIT and distributed widely in the body
- Some may be given parenterally
- Metabolized in the liver and excreted primarily in the urine
Benzodiazepines Pharmacodynamics
- Stimulate GABA receptors in the ascending reticular activating system (RAS) of the brain
- Low dose: decrease anxiety by acting on the limbic system and other areas of the brain that help regulate emotional activity; calm and sedate
- High dose: induce sleep
Benzodiazepines Pharmacotherapeutics
- Clinical indications include relaxing the patient during the day of before surgery, treating insomnia, producing IV anesthesia, treating alcohol withdrawal symptoms, treating anxiety and seizure disorders, and producing skeletal muscle relaxation
Barbiturates
- Major pharmacologic action is to reduce the overall CNS alertness
- Barbiturates that are used primarily as sedatives and hypnotics include amobarbital, aprobarbital, butabarbital sodium, mephobarbital, pentobarbital sodium, phenobarbital, secobarbital sodium
- Low dose: depress sensory and motor cortex of the brain causing drowsiness
- High dose: cause respiratory depression and death because of their ability to depress all levels of the CNS
Barbiturates Pharmacokinetics
- Absorbed well from the GIT and distributed rapidly
- Metabolized in the liver and excreted in the urine
Barbiturates Pharmacodynamics
- Depress sensory cortex of the brain, decrease major activity, alter cerebral function, and produce drowsiness, sedation and hypnosis
Barbiturates Pharmacotherapeutics
- Clinical indications include daytime sedation, hypnotic effects for patients with insomnia, preoperative sedation and anesthesia, relief of anxiety, anticonvulsant effects
- Prolonged use can lead to drug tolerance as well as psychological and physical dependence
Nonbenzodiazepines-Nonbarbiturates
- Act as hypnotics for short-treatment of simple insomnia
- No special advantages over other sedatives
- Include chloral hydrate, ethchlorvynol and zolpidem
- Lose their effectiveness by the end of the 2nd week except zolpidem (35 days)
Nonbenzodiazepines-Nonbarbiturates Pharmacokinetics and Pharmacodynamics
- Absorbed rapidly from the GIT, metabolized in the liver and excreted in the urine
- MOA is not fully known but thought to produce depressant effects similar to barbiturates
Nonbenzodiazepines-Nonbarbiturates Pharmacotherapeutics
- Typically used for short term treatment of simple insomnia, sedation before surgery and sedation before EEG studies
Nonbenzodiazepines-Nonbarbiturates Drug Interactions
- Common when given with other CNS depressants causing additive CNS depression resulting in drowsiness, respiratory depression, stupor, coma and death
Antianxiety Drugs
- Also known as anxiolytics
- Used primarily to treat anxiety disorders
- Three main types: Benzodiazepines, Barbiturates, and buspirone
Buspirone
- Buspirone hydrochloride is the first anxiolytic in a class of drugs known as azaspirodecanedione derivatives
- Fewer side effects than some other common antianxiety drugs
- Advantages: less sedation, no increase in CNS depressant effects when taken with alcohol or sedative-hypnotics, low abuse potential
Buspirone Pharmacokinetics
- Absorbed rapidly; undergoes extensive first pass effect
- Metabolized in the liver and eliminated in the urine and feces
Buspirone Pharmacodynamics
- MOA is unknown
- Does not affect the GABA receptors
- Produce various effects in the midbrain and act as a midbrain modulator
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Description
Test your knowledge on centrally-acting muscle relaxants, their pharmacokinetics, and pharmacodynamics. This quiz covers key medications, their uses, and absorption methods. Perfect for students studying pharmacology or healthcare professionals.
