Strictly speaking it isnt a script at all if people are varying the Qty dispensed.  The vet writing the Script should be considering the time frames that that level of medication would last for. EG He writes the script with enough medication to last for 3mths.   If a different qty was dispensed for example it isnt really a Prescription at all, I would argue that if a employee was using a prescription to generate a dispensing, they should NOT be allowed to vary the qty at all, if they discuss that with the vet and prescribing quidelines ie dose rate changes a new prescription should be generated and the old one marked as expired.

If a client wants MORE of a drug at one dispensing then the employee could effect 2 dispensings at once. IE fill the script twice.  

I would lock the qty and labelling for medication acts generated from prescriptions.  I would have serious concerns if medication dispensed under a script I wrote could be varied on a each dispensing and my name automatically applied to that label.  

Under pharmaceutical guidelines the most a pharmacist can vary is the brand of a drug, not the dose rate or the period and he can confer with the prescriber if he feels the combination of drugs prescribed will cause issues for the patient as well.  But it is up to the prescriber to vary in that case.

I understand the need to maintain flexibility and ensure this project meets the needs of the sponsor, but the provision for dispensing drugs on a long term basis with no input from a veterinarian needs to be carefully managed IMO.

Ben