[CPA]

If I did my math right, there is a reason for diluting herceptin in the solution provided... As you all know, Herceptin is very expensive. It is supplied in powder form, reconstituted as described above, then (usually) added to a 250ml bag of normal saline solution (NSS) for infusion.

The amount required by a 155 lb (70kg) patient, with 2mg/kg dose is 140mg. This means that the pharmacist draws about 6.7ml (about 1/3 as mixed) of the reconstituted solution. The remaining herceptin solution can then be stored for up to 28 days.

If herceptin is mixed with only sterile water, it must be discarded within 24 hours, essentially wasting approximately 2/3 of the solution if it cannot be used during this 24 hour period.

I agree with the pharmacist that the benzyl alcohol (BnOH) is probably not causing the problems. At 1.1% in 20ml, you are only getting about .07 ml of BnOH if you get the dose used in the above example. This is much lower than amounts shown to be safe. Remember, BnOH is naturally found in some fruits and other foods. It is used in other foods as a carrier for flavorings. It is also relatively common in other pharmaceuticals.