Injection solutions are typically prepared through a process involving dissolving the drug, adding a preservative, adjusting the pH, and sterile filtering. This process ensures the final solution is safe and effective for injection.
Steps in Preparing Injection Solutions
The preparation of injection solutions involves several key steps:
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Dissolving the Drug: The active pharmaceutical ingredient (API) is dissolved in a suitable solvent, usually water for injection (WFI).
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Adding a Preservative: A preservative is added to prevent microbial growth, especially in multi-dose vials.
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pH Adjustment: The pH is adjusted to ensure the drug's stability and minimize discomfort upon injection.
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Sterile Filtration: According to reference 9.2, the solution is then passed through a 0.22 µm membrane filter to remove any microorganisms. This sterile filtration, followed by aseptic filling, is particularly important for heat-sensitive drugs.
Why Sterile Filtration?
Many drugs are heat-sensitive, making autoclaving (heat sterilization) unsuitable. Sterile filtration offers an alternative method to ensure sterility without compromising the drug's integrity (Reference 9.2).
Summary
| Step | Purpose | Details |
|---|---|---|
| Dissolving Drug | To create a homogenous solution. | Use appropriate solvent; ensure complete dissolution. |
| Add Preservative | Prevent microbial growth. | Choose compatible preservative at appropriate concentration. |
| pH Adjustment | Ensure stability and reduce injection discomfort. | Use appropriate buffers; monitor pH closely. |
| Sterile Filtration | Remove microorganisms. | Filter through 0.22 µm membrane; perform integrity testing. |
