Karnatakabhashabhushana 6.23

And [they may] end in -su.

For them—namely keccane and so on—there is also the state of ending in -su when a consonant follows.

kisugal;

kisugāḍu;

bisugavir;

bisugal;

pasuvandar;

pasuvol.

Because desired forms are established through the splitting of rules, in some instances ending in -su does not occur:

paccaḍake;

paccōle;

beccaḍi;

beccōḍu.