Buspirone dosage

Direct information appears to be limited to this study but it is consistent with the way rifampicin interacts with many other drugs. This interaction would appear to be clinically important. If both drugs are used be alert for the need to use an increased buspirone dosage. 

However, lorazepam and oxazepam are relatively safe for older adults when given in normal dosages. Buspirone (BuSpar) also is a safe choice for older adults with anxiety because it does not cause excessive sedation, and the risk of falling is not as great. Before bus-pirone therapy is begun, benzodiazepines and sedatives and hypnotics are gradually withdrawn. Buspirone, unlike most of the benzodiazepines, must be taken regularly and is not effective on an as-needed basis. 

The effects of buspirone are decreased when the drug is administered with fluoxetine Increased serum levels of buspirone occur if the drug is taken with erythromycin or itraconazole Should any of these combinations be required, the dosage of buspirone is decreased to 2.5 mg BID, and the patient is monitored closely. Venlafaxine blood levels increase with a risk of toxicity when administered witii MAOIs or cimetidine There is an increased risk of toxicity when trazodone is administered with the phenothiazines and decreased effectiveness of trazodone when it is administered with carbamazepine Increased serum digoxin levels have occurred when digoxin is administered with trazodone There is a risk for increased phenytoin levels when phenytoin is administered witii trazodone... 

To overcome these side effects, buspirone has to be gradually titrated for several days or weeks until it reaches the therapeutic dose, taking weeks for the drug to be effective and not always reaching a fully effective dose. Its short half-life in humans necessitates three-times a day (tid) dosage, which also makes it less attractive compared to the once a day dosage of SSRIs. 

Concomitant therapy When buspirone is to be given with a potent inhibitor of CYP3A4, the dosage recommendations described in the Drug Interactions section should be followed. 

Buspirone is not associated with any withdrawal syndrome. Little is known about discontinuing the dosage, but a conservative approach would include a brief taper. 

Munjack et al. [1991] conducted a pilot study of buspirone in the treatment of social phobia. Subjects meeting DSM-lll-R criteria for social phobia were entered into an 8-week, open-label trial. Buspirone was started at 5 mg twice a day and increased by 5 mg every 2-3 days to a maximum dosage of 60 mg/day, or until side effects prevented further dose escalation. Of the 17 subjects entered in this study, 11 completed it. The 6 dropouts resulted from lack of responsiveness, adverse effects, inability to attend appointments, and a loss to follow-up. At week 6, of the 11 subjects completing the trial, 5 reported a little and 6 endorsed moderate change in their symptomatology. At the end of week 8, two subjects reported a little, 5 noted moderate, and 4 endorsed marked improvement. Although the global measures demonstrated the above results, instruments used to measure the features specific to social phobia demonstrated mixed results. 

The use of buspirone in social phobia has also been investigated by Schneier et al. [1993]. In this 12-week open trial, 21 patients who met DSM-III-R criteria for social phobia and did not display a response during a 1 -week placebo run-in, went on to receive buspirone. The drug was initiated at 5 mg three times a day and was increased by 5 mg/day every 3 days to a maximum dosage of 60 mg/day or until side effects prevented further dose increases. Seventeen patients completed the trial. At the end of week 12, 8 [47%] of the 17 subjects were rated as much to very much improved on the Clinical Global Impression Scale (Guy 1976]. Of those subjects tolerating doses of 45 mg/day or more, 67% [9/12] were at least much improved. ... 

Buspirone is available for oral administration in a variety of dosage forms. The usual initial dosage is 7.5 mg twice a day, increased after... 

Pollack MH, Worthington JJ, Manfro GG, et al. Abecarnil for the treatment of generalized anxiety disorder a placebo-controlled comparison of two dosage ranges of abecarnil and buspirone. J Clin Psychiatry 1997 58(suppl 11) 19-23. 

The recommended initial dose of buspirone is 7.5 mg two times daily with dosage increments of 5 mg/day every 2 to 3 days as needed. The usual therapeutic dose of buspirone is 30 to 60 mg/dayThe onset of improvement in cognitive symptoms (2 weeks or longer) precedes the rehef of somatic symptoms maximum therapeutic benefit may not be evident for 4 to 6 weeks. 

Direct information appears to be limited to this study but the interaction would seem to be established. The dosage of buspirone should be greatly reduced if itraconazole is given concurrently. The manufacturers recommend 2.5 mg daily or twice daily. Ketoconazole is predicted to interact similarly because it is also a potent CYP3A4 inhibitor. ... 

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