Dry powders for injection are a popular parenteral dosage form for drugs that cannot be formulated into ready-to-use injectables because of their instability in aqueous solution. Depending on their formulation strategy, dry powders for injection can be formulated by two strategies.

The first strategy is lyophilization (freeze-drying), where the primary pack allows the formulation of drugs that are thermolabile or unstable in aqueous solution. However, lyophilization normally yields an amorphous or partially amorphous product, which leads to solid-state instability.

The second strategy is the preparation of a more stable crystalline stage that can be obtained by crystallization in aseptic conditions and can be maintained by directly filling the sterile dry-powder drug into pre-sterilized vials. Dry powders for injections are relatively simple formulations with regard to the number of excipients and the manufacturing process.