Pharmaceutical compositions using semi-solid delivery vehicle

A pharmaceutical composition, comprising:

• (a) an active agent;
• and
• (b) a semi-solid delivery vehicle comprising:
• (i) a polyorthoester of formula I or formula II
• 16
• where:
• R is a bond, —(CH2)a—, or —(CH2)b—O—(CH2)c—;
• where a is an integer of 1 to 10, and b and c are independently integers of 1 to 5;
• R* is a C1-4 alkyl;
• n is an integer of at least 5;
• and
• A is R1, R2, R3, or R4, where
• R1 is:
• 17
• where:
• p is an integer of 1 to 20;
• R5 is hydrogen or C1-4 alkyl;
• and
• R6 is:
• 18
• where:
• s is an integer of 0 to 30;
• t is an integer of 2 to 200;
• and
• R7 is hydrogen or C1-4 alkyl;
• R2 is:
• 19
• R3 is:
• 20
• where:
• x is an integer of 0 to 30;
• y is an integer of 2 to 200;
• R8 is hydrogen or C1-4 alkyl;
• R9 and R10 are independently C1-12 alkylene;
• R11 is hydrogen or C1-6 alkyl and R12 is C1-6 alkyl;
• or R11 and R12 together are C3-10 alkylene;
• and
• R4 is a diol containing at least one functional group independently selected from amide, imide, urea, and urethane groups;
• in which at least 0.1 mol percent of the A units are of the formula R1, and
• (ii) a pharmaceutically acceptable, polyorthoester-compatible liquid excipient selected from polyethylene glycol ether derivatives having a molecular weight between 200 and 4000, polyethylene glycol copolymers having a molecular weight between 400 and 4000, mono-, di-, or tri-glycerides of a C2-19 aliphatic carboxylic acid or a mixture of such acids, alkoxylated tetrahydrofurfuryl alcohols and their C1-4 alkyl ethers and C2-19 aliphatic carboxylic acid esters, and biocompatible oils.