ANTI-ANXIETY DRUGS

• Decrease nervousness and tension in normal or neurotic individuals.

• Most common group: BENZODIAZEPINES (Valium is one)

• Depending on the substitution, you have different effects and kinetics.

Basic Effects:

1. Sedative, without marked medullary depression (unlike barbiturates)

2. Anticonvulsant (like barbiturates)

3. Muscle relaxant (decrease gamma activity in brain stem)

4. Hypnotic (shielding, rather than inhibition of reticular formation)

5. No ANS block- No extrapyramidal effects (not anti-cholinergic)

6. Bind to GABA receptor in CNS (chloride channel: increased activity produces membrane potential stabilization): muscle relaxation, sedative, anticonvulsive activity
   

7. 5-Hydroxytryptamine (5-HT) may be influenced to produce antianxiety activity

Clinical Applications:

1. sedation – psychogalvanic reflex

2. alcohol withdrawal

3. anesthesia – dental procedures

4. sleep medication

Metabolism and Kinetics: some (i.e. lorazepam) are eliminated as such, and are considered relatively short acting (10-18 hrs ½ life). Others (i.e. diazepam) are transformed into active and poorly eliminated metabolites (desmethyldizepam), and are considered long acting (20-50 hrs ½ life).

Physical Dependence: may develop; less potential than barbiturates

Adverse Reactions: toxicity is low – drowsiness – effect of alcohol and other drugs on CNS may be reinforced. When given iv: irritaion and local thrombophlebitis

Other Antianxiety Drugs: certain antihistamine drugs (i.e. hydroxyzine). Meprobamates (Miltown, Equanil), an older group of drugs used to relieve anxiety, should also be mentioned. New is Buspirone (structurally similar to halperidol; seems specific for anxiety).

Category: Pharmacology Notes