From memory, I think it's right to say that most pharmaceuticals are excreted in the urine, but not all. Some you can also find in the feces. But I am not sure where the anthelminthic drugs end up, i.e. in urine or feces or both.
At the risk of stating the obvious, pharmaceuticals in general are excreted in the urine, so while they may be present in mixed humanure, diverting the urine from the feces resolves that concern.
Major parts of pharmaceuticals and their metabolites detected in municipal wastewater originate from urine although some substances show reasonable excretion via faeces.
P.S. I am still hoping that in the not too distant future we will also have a Wikipedia article on container based sanitation. Anyone keen to collaborate on this?Thanks to our Cranfield student collaboration, we now do have such a Wikipedia article which is great!