The first way that the previous suspension calculations are made more challenging, is by not just requiring you to calculate the volume needed to meet a required dose, but to calculate the dose given for a particular volume of drug.
This is important for infusions, where part way, it is useful to know teh dose that the patient has received so far.
Suspension questions will often come with a range of additional medical abbreviations that can complicate the calculations. An example of this is the weight to volume ratio, often seen as % w/v.
This is a way to describe the strength of the drug in one figure, rather than in mg per ml.
Another potential complication of suspension questions is the calculations of the required dose based on weight. Whilst this is less of an issue for general nursing, as the typical dose can be used from the BNF, this becomes more relevant in child nursing, and is essential in ODP.
Often a dose will be described as given in 'bolus' this means to inject all at once as opposed to a timed infusion. Bolus questions can require you to calculated 'per bolus', which can throw students off.
Drip calculations, often referred to as gravity sets, have continued to be relevant in specific scenarios, despite them being replaced in most cases by infusion machines. Whilst these calculations have often been seen as the most challenging of the drug calculations, there is a cheat way of working them out.
A rarer question that you may come across is half lives. By approaching this with a simple table, you can turn this question into a very basic calculation.