C17, c20, and c21 substituted neuroactive steroids and their methods of use

A compound of Formula (II-c):

• or a pharmaceutically acceptable salt thereof, wherein:
• each of R2, R4, R6, R7, R11a, and R11b is independently hydrogen, halogen, cyano, nitro, alkyl, alkenyl, alkynyl, carbocyclyl, heterocyclyl, aryl, heteroaryl, —ORA1, —SRA1, —N(RA1)2, —NHC(═O)RA1, —NHC(═O)ORA1, —S(═O)RA2, —SO2RA2, or —S(═O)2ORA1;
• R3 is alkyl, alkenyl, carbocyclyl, heterocyclyl, aryl, or heteroaryl;
• R5 is absent or hydrogen;
• R19 is hydrogen or alkyl;
• each of R21a and R21b is independently hydrogen, halogen, cyano, nitro, alkyl, alkenyl, alkynyl, carbocyclyl, heterocyclyl, aryl, heteroaryl, —ORA1, —SRA1, —N(RA1)2, —NHC(═O)RA1, —NHC(═O)ORA1, —S(═O)RA2, —SO2RA2, or —S(═O)2ORA1;
• or
• R21a and R21b together with the carbon atom to which they are attached form a carbocyclyl, heterocyclyl, or —C(═O)— group;
• Q is —N(RA1)(RA1);
• each instance of RA1 is independently hydrogen, alkyl, alkenyl, alkynyl, carbocyclyl, heterocyclyl, aryl, heteroaryl, an oxygen protecting group when attached to an oxygen atom, a sulfur protecting group when attached to a sulfur atom, a nitrogen protecting group when attached to a nitrogen atom, or two RA1 groups are joined to form an heterocyclic or heteroaryl ring;
• RA2 is alkyl, alkenyl, alkynyl, carbocyclyl, heterocyclyl, aryl, or heteroaryl;
• n is an integer selected from 1, 2, and 3;
• and
• represents a single or double bond, wherein when one is a double bond, the other is a single bond and R5 is absent.