(For children's dosage and administration, see below.) Dosage should be increased more gradually in debilitated or emaciated patients.

### Elderly Patients

In general, dosages in the lower range are sufficient for most elderly patients. Since they appear to be more susceptible to hypotension and neuromuscular reactions, such patients should be observed closely. Dosage should be tailored to the individual, response carefully monitored and dosage adjusted accordingly. Dosage should be increased more gradually in elderly patients.

To Control Severe Nausea and Vomiting: Adjust dosage to the response of the individual. Begin with the lowest recommended dosage.  
I.M. Dosage: Initially 5 to 10 mg (1 to 2 mL) injected deeply into the upper outer quadrant of the buttock. If necessary, repeat every 3 or 4 hours. Total I.M. dosage should not exceed 40 mg per day.   
I.V. Dosage: 2.5 to 10 mg (0.5 to 2 mL) by slow I.V. injection or infusion at a rate not to exceed 5 mg per minute. Prochlorperazine edisylate injection may be administered either undiluted or diluted in isotonic solution. A single dose of the drug should not exceed 10 mg; total I.V. dosage should not exceed 40 mg per day. When administered I.V., do not use bolus injection. Hypotension is a possibility if the drug is given by I.V. injection or infusion.   
Subcutaneous administration is not advisable because of local irritation.

Adult Surgery (for severe nausea and vomiting): Total parenteral dosage should not exceed 40 mg per day. Hypotension is a possibility if the drug is given by I.V. injection or infusion.   
I.M. Dosage: 5 to 10 mg (1 to 2 mL) 1 to 2 hours before induction of anesthesia (repeat once in 30 minutes, if necessary), or to control acute symptoms during and after surgery (repeat once if necessary).   
I.V. Dosage: 5 to 10 mg (1 to 2 mL) as a slow I.V. injection or infusion 15 to 30 minutes before induction of anesthesia, or to control acute symptoms during or after surgery. Repeat once if necessary. Prochlorperazine may be administered either undiluted or diluted in isotonic solution, but a single dose of the drug should not exceed 10 mg. The rate of administration should not exceed 5 mg per minute. When administered I.V., do not use bolus injection.

In Adult Psychiatric Disorders: Adjust dosage to the response of the individual and according to the severity of the condition. Begin with the lowest recommended dose. Although response ordinarily is seen within a day or 2, longer treatment is usually required before maximal improvement is seen.  
I.M. Dosage: For immediate control of adult schizophrenic patients with severe symptomatology, inject an initial dose of 10 to 20 mg (2 to 4 mL) deeply into the upper outer quadrant of the buttock. Many patients respond shortly after the first injection. If necessary, however, repeat the initial dose every 2 to 4 hours (or, in resistant cases, every hour) to gain control of the patient. More than three or four doses are seldom necessary. After control is achieved, switch patient to an oral form of the drug at the same dosage level or higher. If, in rare cases, parenteral therapy is needed for a prolonged period, give 10 to 20 mg (2 to 4 mL) every 4 to 6 hours. Pain and irritation at the site of injection have seldom occurred.  
Subcutaneous administration is not advisable because of local irritation.