Anxiolytics Flashcards
Describe how dose influences the therapeutic effect of these drugs:
These drugs were manufactured as anxiolytics; however at high doses they become “sedative hypnotics”; and at higher doses still, they can induce sleep.
Which class of drugs are clasically considered anxiolytic, and become sedative hypnotics at higher doses?
Benzodiazepines.
What other class of drugs is commonly used to treat anxiety?
Antidepressants; however, they are only effective in the treatment of chronic anxiety.
What are the therapeutic uses for benzodiazepines?
Reduce anxiety and agitation; adjunctive use for enhancing sedation; used to induce an amnesic effect prior to a procedure; PRN use for acute anxiety; they be used to treat acute symptoms related to chronic anxiety.
What are the four classes of anxiolytics?
(1) Benzodiazepines (ideal for acute anxiety); (2) barbituates (modern use is rare; lethal in overdose); (3) buspirone (non-sedating; takes awhile to have an effect); and (4) antidepressants (ideal for chronic anxiety).
How do benzodiazepines exert their effect?
They work by enhancing the effects of GABA (the primary inhibitory neurotransmitter); thus, they reduce neuronal impulses.
Describe the overdose potential with benzodiazepines:
Overdose in the absence of other substances is rarely fatal; those with respiratory compromise are at the highest risk for overdose; treatment involves symptom management.
Describe the mechanism of action for benzodiazepines:
They activate the GABA-A receptor (located throughout the CNS and periphery); this opens chloride channels, allowing chloride influx, and preventing depolarization; this inhibits neuronal transmission.
Describe the anti-convulsant properties of benzodiazepines:
Chloride influx raises the seizure threshold; this is important when considering withdrawal effects – administration of an antagonist may cause a seizure.
What is the primary difference between the various benzodiazepines?
They differ primarily in their pharmacokinetic properties; lipophillicity, metabolism, excretion, half-life, and duration of action.
How does water solubility affect the half-life of benzodiazepines?
The more water soluble drugs have greater phase II (quick, conjugation) metabolism, and a shorter half-life.
What are the ADRs of benzodiazepines?
Sedation, cognitive impairment, ataxia, incoordination, respiratory depression, anterograde amnesia, and paradoxical agitation.
Describe the potential for tolerance to ADRs:
Tolerance can build to all ADRs; this is dependent upon dose and chronicity of use.
How can increased agitation occur with benzodiazepines?
Cognitive impairment can occur separate to sedation; patients with pre-existing cognitive impairment or dementia may have increased agitation as a result; must NOT increase the dose!
How can clinicians assess for ataxia, or a synergistic impairment with alcohol?
Heel-to tandem walking.
When are patients at the highest risk for respiratory depression?
When taking very high doses; when using benzodiazepines in combination with alcohol; or when they have pre-existing respiratory compromise – consider the use of sedative drugs in those with sleep apnea.
