Chlorpromazine hydrochloride is available as a 25 mg/mL injection solution in 1- and 2-mL ampuls.3783 Each mL of solution contains chlorpromazine hydrochloride 25 mg, ascorbic acid 2 mg, sodium metabisulfite 1 mg, sodium sulfite 1 mg, and sodium chloride 6 mg in water for injection.3783
pH
From 3.4 to 5.4.3783
Chlorpromazine hydrochloride injection is administered slowly by deep intramuscular injection into the upper outer quadrant of the buttock, or by direct intravenous injection or intravenous infusion.3783 Subcutaneous injection is not recommended.3783 For intramuscular injection, dilution with sodium chloride 0.9% or procaine hydrochloride 2% (no longer commercially available in the US) has been recommended if local irritation is a problem.3783 For direct intravenous injection, chlorpromazine hydrochloride injection may be diluted with sodium chloride 0.9% to a concentration of 1 mg/mL and administered at a rate of 2 mg at 2-minute intervals or 1 mg/min in adults, or 1 mg at 2-minute intervals or 0.5 mg/min in pediatric patients 6 months to 12 years of age.3783 For intravenous infusion, chlorpromazine hydrochloride injection 25 to 50 mg (1 to 2 mL) may be diluted in 500 to 1000 mL of sodium chloride 0.9%.3783
Intact containers of chlorpromazine hydrochloride injection should be stored at controlled room temperature and protected from light and freezing.3783 Discoloration may occur if exposed to light.3783 A slightly yellowed solution does not indicate potency loss; however, a markedly discolored solution should be discarded.3783
pH Effects
The pH of maximum stability is 6.67 Oxidation of chlorpromazine hydrochloride occurs in alkaline media.4 The titration of chlorpromazine hydrochloride in sodium chloride 0.9% with alkali resulted in precipitation of chlorpromazine base at pH 6.7 to 6.8.138 Precipitation may occur if chlorpromazine hydrochloride is admixed with alkaline drugs or solutions.
Light Effects
Intact containers of chlorpromazine hydrochloride injection should be protected from light during storage.3783 However, chlorpromazine hydrochloride infusion solutions in polyvinyl chloride (PVC) bags exposed to light during administration lost less than 2% of the drug over a 6-hour administration period. Light protection of infusion sets during administration was found not to be necessary.2280
Sorption
Chlorpromazine hydrochloride (May & Baker) 9 mg/L in sodium chloride 0.9% (Travenol) in PVC bags exhibited only about 5% sorption to the plastic bag during 1 week of storage at room temperature (15 to 20°C). However, when the solution was buffered from its initial pH of 5 to pH 7.4, approximately 86% of the drug was lost in 1 week due to sorption.536
Chlorpromazine hydrochloride (May & Baker) 9 mg/L in sodium chloride 0.9% exhibited a cumulative 41% loss due to sorption during a 7-hour simulated infusion through an infusion set (Travenol) consisting of a cellulose propionate burette chamber and 170 cm of PVC tubing. Both the burette chamber and the tubing contributed to the loss. The extent of sorption was found to be independent of concentration.606
The drug also was tested as a simulated infusion over at least 1 hour by a syringe pump system. A glass syringe on a syringe pump was fitted with 20 cm of polyethylene tubing or 50 cm of Silastic tubing. A negligible amount of drug was lost with the polyethylene tubing, but a cumulative loss of 79% occurred during the 1-hour infusion through the Silastic tubing.606
A 25-mL aliquot of chlorpromazine hydrochloride 9 mg/L in sodium chloride 0.9% was stored in all-plastic syringes composed of polypropylene barrels and polyethylene plungers for 24 hours at room temperature in the dark. The solution did not exhibit any loss due to sorption.606
In a continuation of this work, chlorpromazine hydrochloride (May & Baker) 90 mg/L in sodium chloride 0.9% in a glass bottle was delivered through a polyethylene administration set (Tridilset) over 8 hours at 15 to 20°C. The flow rate was set at 1 mL/min. No appreciable loss due to sorption occurred.769 This finding is in contrast to a 41% loss using a conventional administration set.606
Central Venous Catheter
Chlorpromazine hydrochloride (Elkins-Sinn) 2 mg/mL in dextrose 5% was found to be compatible with the ARROWg+ard Blue Plus (Arrow International) chlorhexidine-bearing triple-lumen central catheter. Essentially complete delivery of the drug was found with little or no drug loss occurring. Furthermore, chlorhexidine delivered from the catheter remained at trace amounts with no substantial increase due to the delivery of the drug through the catheter.2335
Drugs in Syringe Compatibility
Y-Site Injection Compatibility (1:1 Mixture)
Additional Compatibility Information
Hydroxyzine and Meperidine
Chlorpromazine hydrochloride (Elkins-Sinn) 6.25 mg/mL, hydroxyzine hydrochloride (Pfizer) 12.5 mg/mL, and meperidine hydrochloride (Winthrop) 25 mg/mL, in both glass and plastic syringes, have been reported to be physically compatible and chemically stable for at least 1 year at 4 and 25°C when protected from light.989
Meperidine and Promethazine
Chlorpromazine hydrochloride, meperidine hydrochloride, and promethazine hydrochloride combined as an extemporaneous mixture for preoperative sedation, developed a brownish-yellow color after 2 weeks of storage with protection from light. The discoloration was attributed to the metacresol preservative content of the meperidine hydrochloride product used. Use of meperidine hydrochloride which contains a different preservative resulted in a solution that remained clear and colorless for at least 3 months when protected from light.1148
Chlorocresol
Chlorpromazine hydrochloride is incompatible with chlorocresol preservative.467; 468
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