Oxacillin sodium is available as a powder in vials containing the equivalent of 1 or 2 g of oxacillin.3852 A 10-g hospital bulk package also is available.3853 The products contain dibasic sodium phosphate 20 mg per g of drug.3852
For intramuscular use, the 1- or 2-g vial should be reconstituted with with 5.7 or 11.5 mL, respectively, of sterile water for injection and shaken well to yield a solution containing oxacillin 250 mg/1.5 mL (167 mg/mL).3852
For intravenous injection, the 1- or 2-g vial should be reconstituted with 10 or 20 mL, respectively, of sterile water for injection or sodium chloride 0.9% to yield a solution containing oxacillin 100 mg/mL.3852 For intravenous infusion, the reconstituted solution should be diluted in an appropriate infusion solution.3852
Pharmacy bulk packages should only be used in the preparation of solutions for intravenous infusion.3853 The 10-g pharmacy bulk package should be reconstituted with 93 mL of sterile water for injection or sodium chloride 0.9% to yield a 100-mg/mL solution.3853 The reconstituted solution should be diluted in an appropriate infusion solution.3852
Oxacillin sodium also is available as a frozen premixed infusion solution of oxacillin 1 or 2 g in 50 mL with dextrose 1.5 g or 300 mg, respectively, and sodium citrate hydrous 150 or 300 mg, respectively, in water for injection in single-dose Galaxy containers.3854 The premixed solutions also contain hydrochloric acid with or without sodium hydroxide to adjust the pH.3854
pH
From 6 to 8.5.3854 At 10 g/L in dextrose 5%, the pH has been variously reported as 7.4149 and 7.94.153 At this concentration in sodium chloride 0.9%, the pH has been reported as 7.73.153
Osmolality
The osmolality of oxacillin sodium 250 mg/1.5 mL in sterile water for injection was 596 mOsm/kg by freezing-point depression and 657 mOsm/kg by vapor pressure.1071
The osmolality of oxacillin sodium 50 mg/mL was 381 mOsm/kg in dextrose 5% and 396 mOsm/kg in sodium chloride 0.9%.1375
The osmolality of oxacillin sodium was calculated for the following dilutions:1054
| Osmolality (mOsm/kg) | ||
|---|---|---|
| Oxacillin in Diluent | 50 mL | 100 mL |
| 1 g in Dextrose 5% | 326 | 295 |
| 1 g in Sodium chloride 0.9% | 353 | 321 |
| 2 g in Dextrose 5% | 379 | 329 |
| 2 g in Sodium chloride 0.9% | 406 | 356 |
The following maximum oxacillin sodium concentrations have been recommended to achieve osmolalities suitable for peripheral infusion in fluid-restricted patients:1180
| Diluent | Maximum Concentration (mg/mL) | Osmolality (mOsm/kg) |
|---|---|---|
| Dextrose 5% | 59 | 530 |
| Sodium chloride 0.9% | 53 | 519 |
| Sterile water for injection | 106 | 422 |
The frozen premixed solution is iso-osmotic.3854
Sodium Content
Oxacillin sodium powder contains 63.77 mg (2.77 mEq) of sodium per gram of oxacillin.3852
Oxacillin sodium is administered by intramuscular injection, direct intravenous injection, or by continuous or intermittent intravenous infusion.3852; 3854 By direct intravenous injection, the dose should be given slowly over approximately 10 minutes.3852 Reconstituted oxacillin sodium injection should be diluted in a compatible infusion solution prior to intravenous infusion.3852
Premixed infusion solutions and solutions prepared from pharmacy bulk packages are administered by intravenous infusion.3853; 3854
Oxacillin sodium is a white to off-white powder that forms a clear, colorless to yellow solution upon reconstitution.3852 Intact vials and pharmacy bulk packages should be stored at controlled room temperature.3852; 3853
When reconstituted with sterile water for injection to a concentration of 250 mg/1.5 mL (for intramuscular injection), the solution is stable for 3 days at room temperature, 1 week under refrigeration, or 30 days frozen at -15°C.3852
When reconstituted with sterile water for injection or sodium chloride 0.9% to a concentration of 10 to 100 mg/mL, the solution is stable for 4 days at room temperature or 7 days under refrigeration.3852 The reconstituted solutions are stable for 30 days frozen at -15°C when reconstituted with sterile water for injection at a concentration of 50 to 100 mg/mL or with sodium chloride 0.9% at a concentration of 100 mg/mL.3852
The closure of the pharmacy bulk package may be penetrated one time with a suitable sterile dispensing set that allows measured dispensing of the contents.3853 The pharmacy bulk package should be discarded within 4 hours of initial entry.3853
The commercially available frozen premixed infusion solution should be stored at -20°C.3854 The manufacturer states that components of the solution may precipitate in the frozen state and will redissolve upon reaching room temperature with little to no agitation.3854 This does not affect the potency of the drug.3854
Frozen solutions should be thawed at room temperature or under refrigeration; solutions should not be subject to force thawing by immersion in water baths or microwaving.3854 Thawed solutions are stated to be stable for 48 hours at room temperature or 21 days under refrigeration.3854 Thawed solutions should not be refrozen.3854
Freezing Solutions
Oxacillin sodium, 500 mg/2.5 mL and 1 g/5 mL in sterile water for injection in glass and plastic syringes and 200 mg/mL in the original vial, was frozen at -20°C. Adequate stability was maintained over 3 months.303
In another study, oxacillin sodium 1 g/100 mL of dextrose 5% in polyvinyl chloride (PVC) bags was frozen at -20°C for 30 days. The bags were then thawed by exposure to ambient temperature or microwave radiation. The solutions had no precipitation or color change and no drug loss. Subsequent storage at room temperature for 24 hours yielded a physically compatible solution, which exhibited a 3 to 4% loss.554
Syringes
Oxacillin sodium (Bristol) 8.33, 16.7, and 33.3 mg/mL in dextrose 5% and in sodium chloride 0.9% packaged in plastic syringes was reported to be stable for 24 hours at room temperature, 8 days refrigerated, and 30 days frozen at -20°C.31
Ambulatory Pumps
The stability of oxacillin sodium 120 mg/mL in sterile water for injection was evaluated in PVC portable infusion pump reservoirs (Pharmacia Deltec). No oxacillin loss in 3 days at 25°C and 5% loss in 14 days at 5°C was found.2080
Sorption
Little loss due to sorption of oxacillin sodium (Bristol) 1 g/100 mL in dextrose 5% and sodium chloride 0.9% in trilayer solution bags (Bieffe Medital) composed of polyethylene, polyamide, and polypropylene occurred in 2 hours. Similarly, no loss was found during a 1-hour simulated infusion.1918
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