[SquarishTriangle (OP)]

Ok, context: I've recently starting doing my clinical rotations at our university's veterinary teaching hospital and around at other veterinary clinics. I've found that certain drug bottles (of various forms and sizes), for single-use, are designed so that you're meant to break the top off and turn the whole bottle upside down before drawing it up (or rather 'down') into a syringe. And it is usually much easier to do it this way than to draw it up from above the bottle. The trouble is, it never says to do it that way on the bottle and I am left reluctant to invert the bottle in case the entire contents pours straight out.

Question: Is there some kind of rule I can use to judge whether or not the liquid contents of a bottle will stay in the bottle if I turn it upside down (eg. Size of the opening? Size of the bottle? Relative size of the opening compared to the volume of the bottle? Compared to the diameter of the rest of the bottle?) without having to risk, say, dosing the floor with morphine?

[lyner]

What do these bottles look like?
Without a very thin neck, a bottle is likely to empty its contents when inverted. Is there a rubber membrane over the neck?

[RD]

The "snap the neck" type is an ampoule. The rubber seal type is a vial.

There is a relevant animation at the bottom of this page.

A filtered drawing needle should be used to remove the drug from the ampoule then another needle used to inject the patient. This is to avoid the possibly of injecting glass fragments from the broken ampoule into patient. This level of caution involves additional cost and may not be applied to patients with four legs, (or two legged ones in the care of public health system).