clozapine and tetracyclic antidepressants

It is an atypical antipsychotic. 

Tetracyclic antidepressant - Wikipedia

carbamazepine and tricyclic antidepressants

Is there a relationship? Carbamazepine is used to treat epilepsy. 

Carbamazepine - Wikipedia

Tricyclic antidepressant - Wikipedia

aciclovir, ganciclovir, valganciclovir, and valaciclovir comparison

All are antivirals. What would be the effect of replacing an alcohol group with a fluorine or a chlorine atom? 

chlorambucil - a melphalan cousin

It is a chemotherapy drug and has structural similarities with several others. 

Derpetology: melphalan, ifosfamide, bendamustine, and cyclophosphamide comparison

sofosbuvir - another fluorouracil cousin

It is used to treat hepatitis C.

Derpetology: fluorouracil and its cousins (fluoropyrimidine)

cephalosporins, beta lactams, and fluorouracil

Below are the general structural formulas for cephalosporin and beta lactam antibiotics. What would be the effect of substituting the sulfur ring with fluorouracil?

norepinephrine, methyldopa, dopamine, and epinephrine comparison

Norepinephrine increases blood pressure and methyldopa reduces it. But why? Could new blood pressure medicines be made by substituting a carboxylic acid group for an amino group?