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What are some Pharmacology considerations when treating Anxiety Disorders?
- Drug categories—antianxiety or anxiolytics Benzodiazepines
- Non-benzodiazepines
- Antihistamines
- Beta blockers
- Antidepressants
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What are Benzodiazepines used for?
- Used in a variety of conditions including anxiety, sleep disorders, acute alcohol withdrawal, preoperative sedation, seizure disorders, short-term for acute mania, and as muscle relaxants
- Work by depressing subcortical levels of the CNS especially the limbic system. Work to potentiate the action of GABA—resulting in a calming effect.
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What are some Benzodiazepines with quick onset of action?
- Diazepam (Valium) onset is very fast—half-life is 30-100 hours
- Flurazepam (Dalmane) fast onset and half-life is 47-100 hours
- Chlorazepate (Tranxene) fast onset and half-life is 30-200 hours.
- Triazolam (Halcion) has a fast onset and half-life of 2-4 hours
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What is the meaning of a Drug’s half-life?
- Determines the time required for a drug to reach its steady state
- Applies to the amount of time needed to “wash out” a drug once it is discontinued
- If a drug has a half-life of 4 days it’s “wash out” time is about 20 days.
- You can determine “wash-out” periods for any drug if you know its half-life
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What is the Formula for determining a drug’s wash-out time?
- What is the drug’s half-life?
- Drug’s half-life multiplied by 5—at this point, over 96% of the drug is “washed out” of the system.
- Valium (diazepam’s) half-life is 20-50 hours.
- What is the wash-out period?
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What are some Benzodiazepines with intermediate onset of action?
- Alprazolam (Xanex) has a half-life of 12-15 hours
- Chlordiazepoxide (Librium) has a half-life of 50-100 hours
- Clonazepam (Klonipin) has a half-life of 18-50 hours
- Moderately fast in it’s action is the drug Temazepam or Restoril and its half-life is 15-30 hours
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What are some Benzodiazepines with a moderately slow onset?
- Oxazepam (Serax) has a half-life of 3-21 hours
- Lorazepam (Ativan) has a half-life of 10-20 hours
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What are some Special considerations with Benodiazepines?
- Adverse reactions or toxicity may occur if patient has decreased liver functions
- Drug has street value
- Dangerous if combined with MAOI’s
- Easy overdose potential if a 2-month supply is prescribed and combined with alcohol
- Riskiest drugs are Ativan and Xanex due to their high potency and short duration of action
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What are some Concepts of drug-tapering versus abrupt withdrawal?
- With abrupt withdrawal, the patient will experience the opposite of the expected effects of the drug (sedative): Increased pulse and elevated blood pressure
- Increased respiratory rate and elevated temperature
- Hand tremor
- Insomnia and anxiety
- Nausea, psychomotor agitation—seizures, hallucinations are rare but can occur
- Drug tapering considerations: Tapering is based on the drug’s half-life
- The term tapering refers to gradually decreasing the amount of the drug a person receives over a course of days or weeks.
- Generally, reduce dose by 25% over 2 weeks and then by 10% until completely discontinued.
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What are some Precautions with prescribing benzodiazepines?
- Adverse reactions or toxicity may occur if patient has decreased liver functions
- Drug has street value
- Dangerous if combined with MAOI’s Easy overdose potential if a 2-month supply is prescribed and combined with alcohol
- Riskiest drugs are Ativan and Xanex due to their high potency and short duration of action
- Elderly clients are more vulnerable to the sedating effects and CNS—the drug is lipophilic and elders have more fat than muscle
- Drugs-BZA’s makes elders prone to falls as well as exacerbating memory deficits and may cause urinary incontinence
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Nonbenzodiazepine—Buspirone or Buspar
- Safer and may be prescribed to elders and children
- May not exert its antianxiety effect for up to 2 weeks with 3-6 weeks for maximum effectiveness
- Not associated with tolerance or dependenceExerts its effects on seratonin receptors
- Educate the patient that this drug is for anxiety control—not sedation
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Difficult prescribing scenarios
- Patient with anxiety who has taken a benzodiazepine has different expectations of how they should feel on the drug
- Benzodiazepines are a quick-fix and the patient will not learn to deal with their personal coping skills instead relying on the drug.
- The goal in anxiety disorders is to adapt, adjust, and improve personal coping skills
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What is the importance of “therapy” to improve outcome?
- Therapy will focus on a person’s negative thinking and help them to practice alternative thought patterns that lead to healthier behavior.
- A realistic time frame for this is 1-3 months
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Other medications used to treat anxiety are?
- Antihistamines such as benadryl, vistaril, and atarax may be used especially with sleeping difficulties
- Beta-blockers such as propanolol and atenolol have been prescribed for social phobia symptoms
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