Is in that a standard rule when to draw a drug serum indication at trough, or does it other depend on the drug best moment?

Antibiotics: For IV drugs, is it correct to draw a sample 30-60 minutes post administraton... but this humane of rule doesn't apply to PO drugs since they vary within peak?Is in that a standard rule when to draw a drug serum indication at trough, or does it other depend on the drug best moment?
You want to draw a trough right past the next dose. However if a trough is drawn precipitate, you can forward extrapolate to find the correct blood levels. Drawing a height is different. You must wait for the drug to distribute. For example, aminoglycosides are done next to a 30 minute infusion time with a 30 minute hang around time to draw peak level or a one hour infusion then straight away draw levels. If level are drawn late, you can rear extrapolate to calculate the proper pinnacle.
The trough is like you said, 30-60 mins formerly next dose because thats duplicate with any drug. This have been choosen because it give a time when a known utility has be established for each drug. Same next to the peak. I hope I haven't confused you even more.