What Do You Need to Know About the Stability of Injectable Drugs

The stability of injectables in pharmaceuticals is a paramount concern to all pharmaceutical companies. The degree of stability determines how long the drug can maintain its original potency and hence affects the quantity, efficacy and cost-effectiveness of pharmaceuticals.

What are Injectables?

Injectables are medications that are taken by injection into the body. They include drugs like insulin, blood pressure medication, and painkillers. Because they are injected into the body, injectables are also known as “parenteral” medications.

What are the factors that affect the stability of injectable medications?

Injectable medications are typically stable over a three-month period when stored at room temperature. However, shorter storage times may be required for heat-sensitive medications.

Keep medicines refrigerated and out of the sunlight if possible to extend their shelf life. Also, don't freeze them.

It is advisable to store your injectables in a cool, dry place. A refrigerator (below 7ºC) will be adequate for most drugs and most of the time. In some cases you may want to keep medicines at 4–10ºC, but avoid taking them out of their original packaging until ready to use. Temperature can affect them so they should be thrown away if they are not stable or getting alterer, even if they still have an expiry date. It's important to follow all safety instructions on a medicineís label, including any that are provided by a pharmacist or physician.

Adding preservatives to injectables

When a patient requires an injection, they may have to choose between injecting a pre-mixed solution of the drugs and having them professionally mixed at a pharmacy. There are pros and cons to each approach.

Pros of pre-mixed injections:

• They are ready to use right away, without the need for refrigeration or mixing.
• There is less chance of drug incompatibility since the doses have been standardized in advance.
• There is less risk of needle-stick injuries since the medication is diluted in advance and drawn up directly into the syringe.
• Medications are usually available more quickly when pre-mixed than when they are professionally mixed.

Cons of pre-mixed injections:

• Medications can be more expensive when pre-mixed because pharmacies charge for the service.
• Pre-mixed injections can be less effective than when they are professionally mixed because of variations in drug concentrations from batch to batch.

Additives like dyes and excipients

Injectable drugs are often supplemented with additives like dyes and excipients to improve stability, aesthetics, and performance. However, improper combinations or the addition of these substances can result in drug instability. Here’s what you need to know about the stability of injectable drugs:

1. Drug stability is a crucial issue for drug manufacturers. Improper combination or addition of additives can lead to drug instability, which can result in adverse events like allergic reactions and even patient safety concerns.

2. To ensure the stability of injectable drugs, manufacturers typically test the formulations with various combinations of additives before production. This approach helps to avoid potential problems down the line.

The stability of injectable drugs also depends on the physical properties of the formula which is required to form a solution at room temperature. Some drugs combining additives like controlled lipid emulsions (CLES) and sterile water are added in all injectable formulations, while others like stabilizers, lubricants, and preservatives are used specifically as per the needs of various brands.

Manufacturing and distribution systems

Manufacturing and distribution systems are key to the stability of injectable drugs. If the system is not stable, there is a greater chance that the drug will not be safe or effective when it is administered to patients. There are many factors that can impact stability, such as changes in volume, temperature, or pressure. The stability of the manufacturing and distribution system must be evaluated regularly.

The storage, preparation and delivery process must be stable, clear and specific instructions must be provided to all participants in the system regarding the handling, preparation, delivery and storage of the drug. For example:

Medical device manufacturers should consider conducting Long-Term Stability (LTS) studies with their finished medical devices using a clinically tested comparator. Medical device manufacturers should consider performing LTS studies on products that have not previously undergone quantitative risk assessment for potential short-term or long-term systemic effects. The outcome measures used could include changes in shape or size of the device from study initiation to study termination and long-term assessments based on patient reports at 4 years post-baseline as well as qualitative patient-reported data.

Drug companies should consider performing Long-Term Stability (LTS) studies with modified devices containing active components for which an inherent hazard has been established thus decreasing the need to perform extensive pharmaceutical drug purification. Examples of these modified products include implants, biologics, vaccines and gene therapies. Medical device users should bring any such modified product or materials to the attention of their professional advisers and encourage them to request that companies sponsor LTS studies with their finished product, as appropriate. Medical Device Manufacturers should also consider requesting Long-Term Stability (LTS) studies from their contract research organizations (CROs) since this will ensure that clinical trials are closely monitored even when analytical results are not available in time for use in a management decision.

Conclusion

There are a lot of variables that go into the stability of injectable drugs, and as such, it is important to be aware of the risks involved should you need to use them in a medical setting.