Reconstitution calculations

In this video tutorial we'll be looking at reconstitution calculations.

There are some active pharmaceutical ingredients that by their very nature are unstable in the aqueous environment even when exposed for short periods of time. A classic example would be antibiotics.  Because antibiotics are unstable in aqueous environment they are typically prepared or formulated as a dry powder through a freeze drying process to enhance the shelf life. However, before the powdered drug is used parenterally, you need to get it back into true solution before you can inject it and this is where reconstitution comes into the picture.

Reconstitution is essentially the process through which you take a dry powdered drug and completely dissolve it using a diluent. You add a specified volume of diluent based on the formulation parameters to the dry powder, to give you your reconstituted preparation which has a specific concentration. Sterile water for injection and bacteriostatic water for injection are typical diluents used for reconstitution. You just want to keep in mind that your final reconstituted solution should be free from particulates of any kind and should be as clear as the diluent that was used.

Here is what we would be covering in this reconstitution calculations tutorial:

1. The sources of the diluent: that is, where you find the information regarding how much volume of diluent to add to the dry powder drug.

2. Three strategic examples:

  • Example one will illustrate how you calculate powder volume and I'll talk about that parameter down the line and
  • Example 2 will demonstrate how you determine the dose once you have got a reconstituted preparation of a known concentration
  • Example 3 will show how you compute the volume of diluent given the other variables

 Hopefully, you found this video tutorial useful and reviewed the pertinent concept concerning reconstitution calculations. If you feel you have master reconstitution calculations, you may want to try the reconstitution calculations quiz.