Phenobarbital sodium injection is available as a 65- or 130-mg/mL solution in 1-mL vials.3855 Each mL of solution contains phenobarbital sodium 65 or 130 mg with alcohol 10% (v/v) and propylene glycol 67.8% (v/v) in water for injection.3855; 3856 Some products also contain benzyl alcohol 1.5% (v/v) as a preservative.3855 Hydrochloric acid may be added for pH adjustment.3855
Phenobarbital sodium also is available as a lyophilized powder in single-dose vials containing 100 mg of phenobarbital sodium (equivalent to 91.35 mg of phenobarbital).4074 The powder formulation does not contain benzyl alcohol or propylene glycol.4074 Reconstitute each vial with 10 mL of sodium chloride 0.9% to yield a solution containing phenobarbital sodium 10 mg/mL.4074 Swirl gently until the contents are completely dissolved.4074
Other formulations, concentrations, or packages sizes may be available.
pH
Injection solution: 9.2 to 10.2.3855
Powder: 9.2 to 10.4074
Osmolality
The osmolality of phenobarbital sodium 65 mg/mL was 15,570 mOsm/kg by freezing-point depression and 9285 mOsm/kg by vapor pressure.1071 The osmolality of phenobarbital sodium 200 mg/mL was 10,800 mOsm/kg.
The osmolality of phenobarbital sodium 100 mg was calculated for the following dilutions:1054
| Osmolality (mOsm/kg) | ||
|---|---|---|
| Diluent | 50 mL | 100 mL |
| Dextrose 5% | 296 | 289 |
| Sodium chloride 0.9% | 325 | 317 |
Trade Name(s)
Luminal Sodium, Sezaby
Phenobarbital sodium injection solution may be administered by deep intramuscular injection into a large muscle or by slow intravenous injection.3855 For intramuscular administration, no more than 5 mL should be injected at any one site because of possible tissue irritation.3855 For slow intravenous injection, the rate of administration should not exceed 60 mg/min.3855
Reconstituted solutions of phenobarbital sodium prepared from the lyophilized powder are intended only for intravenous infusion over 15 minutes into a large peripheral vein.4074
Extreme care should be taken to prevent extravasation or intra-arterial injection.3855; 4074 Extravascular injection may cause local tissue damage with subsequent necrosis.3855; 4074 Intra-arterial administration is contraindicated; potential consequences of intra-arterial injection vary from transient pain to limb gangrene.3855 Any evidence of limb pain during phenobarbital sodium administration warrants stopping the injection.3855; 4074
Subcutaneous administration is not recommended because tissue irritation, including necrosis, may occur.3855
Phenobarbital sodium injection is a clear, colorless solution.3855 Intact containers should be stored at controlled room temperature.3855 The solution should not be used if it is discolored or contains a precipitate.3855
Phenobarbital sodium lyophilized powder is white to off-white and forms a clear, colorless solution upon reconstitution.4074 Intact vials should be stored at controlled room temperature in the original carton to protect from light.4074
Reconstituted solutions in the vial, if not used immediately, should be placed back in the original carton to protect from light and may be stored at room temperature (20 to 25°C) for up to 8 hours or refrigerated (2 to 8°C) for up to 24 hours.4074 Any unused portion of the reconstituted solution should be discarded after the recommended storage duration.4074
Phenobarbital sodium injection solution under simulated summer conditions in paramedic vehicles was exposed to temperatures ranging from 26 to 38°C over 4 weeks. Analysis found no loss of the drug under these conditions.2562
Phenobarbital sodium 10% (w/v) in aqueous solution showed 7% decomposition in 4 weeks when stored at 20°C. There was no measurable decomposition in 8 weeks with storage at -25°C.233
In addition, the stability of phenobarbital sodium injection solution diluted to a 10-mg/mL concentration in sodium chloride 0.9% for use in infants was studied. When stored at 4°C, the dilution was physically compatible with no loss of drug over 28 days.1294
Phenobarbital sodium may raise the pH of admixture solutions to the alkaline range and, therefore, should not be mixed with alkali-labile drugs.47
Plasticizer Leaching
Phenobarbital sodium 6 mg/mL in dextrose 5% did not leach diethylhexyl phthalate (DEHP) plasticizer from 50-mL polyvinyl chloride (PVC) bags in 24 hours at 24°C.1683
Filtration
Phenobarbital sodium 130 mg/L in dextrose 5%, sodium chloride 0.9%, and Ringer’s injection, lactated filtered over 12 hours through a 5-µm stainless steel depth filter (Argyle Filter Connector), a 0.22-µm cellulose ester membrane filter (Ivex-2 Filter Set), and a 0.22-µm polycarbonate membrane filter (In-Sure Filter Set), showed no loss due to binding to the filters.320
For a list of references cited in the text of this monograph, search the monograph titled References.