Sedative-Hypnotics (Benzos, Imidazos, Pyrrolos) Flashcards

1
Q

What are 3 general clinical uses of the sedative hypnotic drugs?

A

Insomnia
Anxiety disorders
Alcohol withdrawal

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2
Q

Describe the dose dependent effects of sedative hypnotics

A

Increasing the dose increases the degree of sedation, which could eventually lead to coma and death

Benzodiazepines have a plateau or “tailing off” where they no longer produce sedative effects

Barbiturates are more dangerous and continually increase sedation with inc dose

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3
Q

What receptor do all the sedative hypnotic drugs work on?

A

GABA-A

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4
Q

Describe the GABA-A receptor. It is ___tropic. What activates it and what happens downstream?

A

Inotropic

Requires an alpha, beta, and gamma subtype to function

Activated by GABA> Leads to inc Cl- channel opening, leading to Cl- influx and an IPSP. Causes hyperpolarization and decreased neuron firing.

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5
Q

What determines the subtype of the GABA A receptor?

A

Alpha subunit

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6
Q

Describe the BZ1 subtype

A

a1B2y2

Can bind benzodiazepines, imidazopyridines, or pyrrolopyrazines

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7
Q

Describe the BZ2 subtype

A

a2B3y2 or (a3,a5)Bny2

Binds ONLY benzodiazepines

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8
Q

What part of the GABA-A receptor binds GABA?

A

Alpha-Beta interface

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9
Q

What part of the GABA-A receptor binds drugs (benzos, imidazos, pyrrolos)?

A

Alpha-Gamma interface

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10
Q

What part of the GABA-A receptor binds barbiturates?

A

Intracellular beta portion

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11
Q

Where does the benzodiazepine antagonist flumazenil bind the GABA A receptor?

A

Alpha-Gamma interface

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12
Q

What is the primary indication for flumazenil and what is one potential contraindication or drawback?

A

Benzodiazepine overdose, but may cause withdrawal symptoms in patients who have been on benzodiazepines for a long time

May also be used to reverse Benzodiazepine sedation after surgery

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13
Q

What is the MOA of Beta-Carbolines?

A

Inverse agonists –> negative allosteric modulators of GABA receptor function

Bind BZ1 or BZ2 sites and block benzo effects

Lead to decreased frequency of chloride channel opening

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14
Q

What are the basic MOAs of benzodiazepines, imidazopyridines, and pyrrolopyrazines?

A

Positive allosteric modulators of GABA-A receptor

They bind their sites, increase GABA’s affinity for the alpha-beta receptor site, increase frequency of Cl- channel opening, IPSP, decreased neuron firing

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15
Q

What is the basic MOA of barbiturates?

A

Increase DURATION of Cl- channel opening in the presence of GABA

Does NOT bind BZ1 or BZ2 sites

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16
Q

Benzodiazepines

Indications

A
Anxiety disorders
Insomnia
EtOH withdrawal
Anticonvulsant effects
Skeletal muscle relaxation
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17
Q

List the Benzodiazepines

A

Midazolam
Alprazolam
Tiazolam
Estazolam

Diazepam
Lorazepam
Oxazepam
Temezepam
Clonazepam

Chlordiazepoxide
Chlorazepate

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18
Q

Benzodiazepines

Metabolism

A

All undergo Phase I oxidation and Phase II conjugation, except…

LOT only go through Phase II glucoronidation (Lorazepam, Oxazepam, Temazepam)

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19
Q

Benzodiazepines

Solubility and Protein binding

A

Lipid soluble

Highly protein bound, so drug-drug interactions are likely

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20
Q

How does the half life of benzodiazepines contribute to potential toxicity and adverse effects?

A

Short half life – concentration remains pretty consistent day to day

Long half life– drug conc accumulates to a much higher concentration, which could lead to oversedation

21
Q

What is diazepam’s active phase I metabolite? How long does it take after diazepam withdrawal for it to clear from your system?

A

Desmethyldiazepam is the primary metabolite

Takes 6-7 to clear from a patient’s system after stopping diazepam

22
Q

How does hepatic function affect benzodiazepine blood levels?

A

Tend to stay elevated longer in elderly patients with decreased hepatic function

23
Q

Benzodiazepines

Adverse Effects

A

Drowsiness
Ataxia
Amnesia

Confusion
Paradoxical excitement
Dizzy

Paradoxical rage
Allergic rxn

24
Q

Benzodiazepines

Tolerance and Dependence

A

Physical dependence can occur in pts who take large doses for long periods of time

Can develop tolerance to sedative effects of benzodiazepines over time, but tolerance is NOT developed to their anxiolytic effects

25
Q

Symptoms of Benzodiazepine Withdrawal

A
Anxiety
Insomnia
Loss of appetite
HA
Nausea
Tremor
Muscle aches
Sweating
Irritability

Rare: Confusion, Delirium, Psychosis, Seizures, Catatonia

26
Q

How could each of these factors increase risk for tolerance and dependence?

  • T 1/2
  • Time to drug onset
  • Potency
  • Dose
  • Time length drug taken
A
  • Low T 1/2
  • Short time to drug onset
  • High Potency
  • High Dose
  • Long time length drug taken
27
Q

List the imidazopyridines

A

Zolpidem

Zaleplon

28
Q

What is the only Pyrrolopyrazine?

A

Eszopiclone

29
Q

What drug can block effects of imidazopyridines and pyrrolopyrazines?

A

Flumazenil (benzodiazepine antagonist)

30
Q

Imidazopyridines and Pyrrolopyrazine Dependence Risk

A

Lower than for benzodiazepines, but can still be habit forming

31
Q

Imidazopyridines and Pyrrolopyrazine

Adverse Effects

A
HA
Dizziness
Somnolence
Nausea
Vomiting
Diarrhea
Anterograde amnesia
Rebound insomnia

Sleep driving and sleep eating with no memory of event

32
Q

Relative half lives of Imidazopyridines and Pyrrolopyrazine

A

Zolpidem- 1.5-3 hrs

Zaleplon- 1 hr

Eszopiclone- 6 hrs

33
Q

List the Barbiturates

A

Phenobarbital

Methohexital

Thiopental

34
Q

Barbiturates

MOA at low and high doses

A

Low doses – bind intracellular GABA-A Beta subunit; increase DURATION of Cl- channel openings

High doses- directly activate Cl- channel opening independent of GABA

35
Q

Barbiturates

Adverse Effects

A

Low therapeutic index that is lethal at 10x the hypnotic dose

Potent resp depression, esp when combined with alcohol

Can cause physical dependence and withdrawal

36
Q

Barbiturates

Metabolism

A

Stimulates CYP450 activity and induces hepatic microsomal oxidases

May increase metabolism of other drugs

37
Q

Ramelteon

MOA

A

Melatonin receptor (MT1 and MT2) agonist

38
Q

What is 1st, 2nd, and 3rd line therapy for insomnia?

A

1st: CBT and Sleep Hygeine
2nd: Work up for underlying cause of insomnia
3rd: Sedative Hypnotic Drugs

39
Q

Which sedative hypnotic is most commonly prescribed for insomnia treatment?

A

Temazepam

40
Q

Which sedative hypnotics should be used more in elderly people? Why?

A

LOT = Lorazepam, Oxazepam, Temazepam

Elderly ppl have lower liver function, so it is better to give them drugs that don’t require phase I oxidation via the liver

41
Q

How are benzodiazepines dosed for insomnia treatment?

A

In general, you don’t want them to take the drug more than 3 nights per week so they don’t associate a good night’s sleep with the drug

Should be used short term (1-3 months)

42
Q

What might happen after cessation of benzodiazepine for insomnia?

A

Rebound insomnia – original symptoms recur, or reoccur in greater intensity

Withdrawal

43
Q

Herbal Preps
Valeriana officinalis
What is the active compound and its MOA?

A

Sesquiterpenes: mediate GABA release and inhibit GABA breakdown

Useful for 4 weeks insomnia

44
Q

Herbal Preps
Chamomile
What is the active compound and its MOA?

A

Apigenin, a benzodiazepine agonist

45
Q

What are the two currently available FDA-approved OTC sleep aids? Active compounds and general MOA?

A

Unisom – contains doxylamine (antihistamine)

ZzzQuil- contains diphenhydramine (antihistamine)

46
Q

Buspirone

MOA

A

5HT 1A partial agonist

47
Q

Buspirone

Drug Interactions

A

DO NOT use buspirone with a MAOI

-Need to clear system of either drug entirely before starting the other, or you risk Serotonin Syndrome

48
Q

Buspirone

Indications

A

Anxiety disorder(with antidepressants)

Major depression (with antidepressants)