Drug Stability, Compatibility, & Storage

Drug Stability

The ability of a drug to maintain its identity, strength, quality and purity over time.

Compatability

The capacity for 2 or more substances to be used together without causing undesired interactions

Storage Requirements

Conditions (temperature, humidity, light exposure) needed to keep a medication stable.

Temperature

Many meds have an optimal range. Exceeding this can lead to degradation. (Factors Affecting Stability)

Humidity

This can affect solids, causing them to clump or degrade faster. (Factors Affecting Stability)

Light Exposure

UV light can degrade photosensitive drugs, leading to discoloration or loss of potency. (Factors Affecting Stability)

Air/Oxygen

Oxidation can significantly reduce a drug’s potency (Factors Affecting Stability)

Freezer

-25°C - -10°C (-13°F - 14°F)

Refrigerated

2°C - 8°C (36°F - 46°F)

Cold

Any temperature not exceeding 8°C (46°F)

Cool

8°C - 15°C (46°F - 59°F)

Controlled Room Temperature

20°C - 25°C (68°F - 77°F)

Warm

30°C - 40°C (86°F - 104°F)

Ambient

Warmer than 40°C (104°F)

Physical Incompatabilties

*Often visible

-Color Changes

-Precipitation

-Cloudiness

Chemical Incompatabilities

*Not always visible

-pH testing

-Other chemical assays

Incompatibility Warning Signs

-Color Changes

-Haziness

-Crystal Formation

Beyond Use Dating (BUD)

The date after which a compounded nonsterile preparation should not be used

BUD: 14 Days

Nonpreserved Aqueous Doses: No preservative and high water content makes them more prone to microbial growth.

BUD: 35 Days

Preserved Aqueous Doses: Have appropriate preservative systems but still high water content.

BUD: 90 Days

Oral Liquids (Nonaqueous): Very low water activity, reducing the risk of microbial contamination.

BUD: 180 Days

Other Nonaquous Doses: Capsules, ointments, and other dosage forms with low water content.

Insulin Storage

-Refrigerate unopened vials/pens ar 2-8°C

-Opened vials/pens can be stored at room temp for directed time frames (ex. 28 days)

Insulin Stability

-High heat of freezing renders insulin ineffective

-Discard if out of recommended range for specified duration

-Visual Check: Look for clumpy, frosting, or clarity changes

Injectables Stability & Storage

Some require refrigeration, some can be left at room temp. Photosensitive injectables may need amber bags or foil wrappings. When reconstituted or mixed, stability may change drastically.

Vaccines Stability & Storage

Typically stored at 2-8°C, but some require ultra-cold freezers. Continuous temperature monitoring; alarm systems in place if changes occur. Most of these have a small window after opening (date/time vials after opening).

Reconstituted Oral Suspensions

Before Reconstitutions

-Generally stored at room temp

After Reconstitutions

-Most require refrigeration

-Shake well; may separate over time

Special Handling and Documentation

-Maintain temperature logs

-Report temperature excursions

-Document compatibility checks for admixtures