Pentamidine isethionate is available as a lyophilized powder in single-dose vials containing 300 mg of the salt.3311 For intramuscular injection, the vial contents should be reconstituted with 3 mL of sterile water for injection at 22 to 30°C.3311 For intravenous administration, the vial contents should be reconstituted with 3 to 5 mL of sterile water for injection or dextrose 5% at 22 to 30°C; then the dose should be withdrawn from the vial and further diluted in 50 to 250 mL of dextrose 5% for administration.3311
Sodium chloride 0.9% should not be used initially to reconstitute pentamidine isethionate because precipitation will occur.3311
pH
From 4.5 to 7.5.3312
Equivalency
Pentamidine isethionate 1.74 mg is equivalent to pentamidine 1 mg.3315; 3316 Care should be taken to clarify upon which moiety (i.e., salt or base) a dosage is expressed and to ensure that no confusion exists with other pentamidine salts.3314; 3315; 3316
Trade Name(s)
Pentam 300
Pentamidine isethionate injection may be administered by intravenous infusion or deep intramuscular injection.3311 Regardless of the route of administration, patients receiving the drug should be in the supine position and their blood pressure should be monitored closely during administration and several times thereafter until the blood pressure has stabilized.3311
For intravenous infusion, the calculated dose should be diluted in 50 to 250 mL of dextrose 5% prior to administration and infused over 60 to 120 minutes.3311 The drug should not be administered by rapid intravenous injection or infusion.3311
Extravasation of pentamidine isethionate may cause ulceration, tissue necrosis, and/or sloughing at the site of injection.3311 The intravenous needle or catheter must be properly positioned and closely observed throughout administration.3311 If extravasation occurs, the injection should be discontinued immediately and restarted in another vein.3311
Intact vials of powder should be stored at controlled room temperature and protected from light.3311
Reconstituted solutions prepared with sterile water for injection are stable for 48 hours in the original vial at room temperature if protected from light.3311 Reconstituted solutions should be stored at 22 to 30°C to avoid crystallization.3311 Solutions for intravenous infusion prepared in dextrose 5% containing pentamidine isethionate 1 and 2.5 mg/mL are stable for up to 24 hours at room temperature.3311 Because no preservative is present, the manufacturer recommends discarding any remaining solution.3311
Solutions should be visually inspected for particulate matter and discoloration prior to administration.3311
Pentamidine isethionate (Fresenius Kabi) 0.8 to 98 mg/mL in sterile water for injection in polyvinyl chloride (PVC) bags and glass vials has been reported to be stable for 30 days at 4°C.3312
Freezing Solutions
The manufacturer states that pentamidine isethionate solutions should be stored at 22 to 30°C to avoid crystallization.3311
Pentamidine isethionate (Fresenius Kabi) 1 to 30 mg/mL in dextrose 5% and sterile water for injection in PVC bags has been reported to be stable for 90 days at -20°C.3312 Pentamidine isethionate (Fresenius Kabi) 0.8 to 2.5 mg/mL in dextrose 5% in PVC bags has been reported to be stable for 120 days at -20°C.3312
Pentamidine isethionate (Fresenius Kabi) 0.8 to 98 mg/mL in dextrose 5% and sterile water for injection in glass vials has been reported to be stable for 90 days at -20°C.3312
Syringes
Pentamidine isethionate (Fresenius Kabi) 0.8 to 97 mg/mL in dextrose 5% and sterile water for injection packaged in disposable plastic syringes has been reported to be stable for 30 days at 4°C and 120 days at -20°C.3312
Elastomeric Reservoir Pumps
Pentamidine isethionate (Fujisawa) 3 mg/mL in dextrose 5% and 2 mg/mL in sodium chloride 0.9% was evaluated for binding potential to natural rubber elastomeric reservoirs.2014 No binding was found after storage for 2 weeks at 35°C with gentle agitation.2014
Sorption
One study that demonstrated stability of pentamidine isethionate (Lyphomed) 1 or 2 mg/mL in dextrose 5% or sodium chloride 0.9% for 48 hours at 22 to 26°C in PVC bags also demonstrated losses of 2 or 10% when 2-mg/mL solutions in dextrose 5% or sodium chloride 0.9%, respectively, were infused through a PVC infusion set, potentially suggesting adsorption of the drug to the set.1142
For a list of references cited in the text of this monograph, search the monograph titled References.