A salt represented by the formula (I).

##STR00001##

wherein Z.sup.+, Q.sup.1, Q.sup.2, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, Z, X.sup.1, X.sup.2, X.sup.a, X.sup.b, L.sup.1, L.sup.2, L.sup.3 and L.sup.4 are defined in the specification.

A semi-solid delivery vehicle contains a polyorthoester and an excipient, and a semi-solid pharmaceutical composition contains an active agent and the delivery vehicle. The pharmaceutical composition may be a topical, syringable, or injectable formulation; and is suitable for local delivery of the active agent. Methods of treatment are also disclosed.

The invention features methods and compositions for the synthesis of multimerizing agents.

The invention features methods and compositions for the synthesis of multimerizing agents.

Provided are compounds that can find use as nitrosation reagents. Provided are nitrosation methods that include reacting a substrate with one of the provided nitrosation reagents and thereby generating a nitrosation product. Provided are kits including a nitrosation reagent. Provided are compositions wherein the nitrosation reagent is enriched in the .sup.15N isotope.