Preparation, Compounding and Stability

Part of Trial Pharmacy (PHARM) Training: Prescription Review and Dose Verification.

About 2 minutes. Free, in your language, no account needed.

Why this matters

Once you reconstitute or dilute, a clock starts. In-use stability is usually much shorter than shelf stability, and it is specified for a reason.

A dose prepared correctly and administered outside its in-use window is a deviation, and may be a clinical problem.

Follow the pharmacy manual exactly

Diluent type and volume. Order of addition. Whether to shake or invert. Container material, since some products bind to certain plastics. Filter requirements. Light protection.

These are not stylistic. A product prepared in the wrong container may deliver less than the stated dose.

If the manual and the protocol differ, ask rather than choose.

Label what you prepare

Participant identifier, study number, kit number, product as the protocol describes it, dose, route, time of preparation, expiry time, and the preparer.

Expiry time, not expiry date. An in-use window of four hours needs a clock time on the label, because the person administering it cannot calculate it from a date.

Aseptic requirements

Where the protocol requires aseptic preparation, the environment and technique are part of the requirement.

A dose prepared outside a required environment is not rescued by good technique, and the deviation is reportable.

Communicate the window

Tell the clinical team the expiry time when you hand over, and make sure it is on the label rather than only in a conversation.

Doses wait. Participants are delayed, lines fail, clinics run over. A four-hour window can expire while a dose sits in a fridge on a ward.

In practice

You prepare an infusion with a four-hour in-use window at 10:15. The clinic is running late.

You label it as expiring at 14:15, tell the nurse, and agree that if administration has not started by then you will be called.

At 14:20 it is discarded and a new dose prepared. It is wasted product, recorded as wastage, and it is the correct outcome.

What this looks like when it goes wrong

A dose is prepared at 09:00 and given at 15:00 because the participant's visit was delayed. The label showed a date but not a time.

Nobody knowingly did anything wrong. The participant received product outside its validated stability window, which is a deviation and a possible under-dose.

Key takeaways