The intravenous route is not FDA approved and is generally not recommended except when no other alternatives are available. Intravenous administration appears to be associated with a higher risk of QT prolongation and torsade de pointes (TdP) than other forms of administration. The manufacturer recommends ECG monitoring for QT prolongation and arrhythmias if IV administration is required. A dose in the range of 1 to 5 mg IV has been suggested, with the dose being repeated at 30 to 60 minute intervals, if needed. A maximum IV dose has not been established. The lowest effective dose should be used in conjunction with conversion to oral therapy as soon as possible.
Nitschke and Stewart 3 state that the oral form of Nembutal sold in 100ml bottles (sterile bottles) at a concentration of 60mg per ml (. 6 grams in a bottle) is enough to provide a peaceful death, although in some cases this can take up to 24 hours. For powdered Chinese Nembutal which is sold in higher quantities, 10grams dissolved in 50ml of water is suggested, and forum posts suggest this is a more reliable dose whilst also being easier to ingest. They recommend ceasing any other medications a few days before taking Nembutal. There is also non-sterile (green coloured) Nembutal that is concentrated 300mg per ml, in which case a 50ml sample equates to 15 grams, and is more than enough for a peaceful death. Compassion in Dying 5 recommend 6g - 9g of Nembutal. Dignitas use 15 grams of a concentrated soluble form of Nembutal that can be swallowed in a few mouthfuls. 3, 6