Drug Expiration Date After Opening

There are so many jingles around today on the danger of using expired products. This includes drugs and drug related products. The national agency for food and drug administration and control (NAFDAC) is on the matter of making sure every drug and food package for consumption is well labelled with the expiry date.

In use shelf life of drugs

Because of this enlightenment, many people who come to the pharmacy to get drugs either ask to know the date of the product or check it out themselves. However, I am yet to see anyone ask for the expiry period of any drug or drug related products after opening the pack or container.

Read Also: Prevent expired drugs tricks

Drugs come in different forms such as liquid, solid, semis solid and gas or aerosol forms. These forms are packed in a single unit for one time use or multiple units for multiple use. Some solid dosage forms come in sachets with each product in a blister pack or in a cup. Liquid comes in a single sachet or bottle and gas or aerosol in a special canister. Semi solids like creams and ointments come in tubes or cups and jars.

When looking at the date of expiry for a single unit product, the major thing is the expiry date stated by the manufacturer. This is because after use, it cannot be used again. But this is not the case when we talk about multiple unit products. After opening, the product can begin to lose stability, hence efficacy. And according to the law in many countries, it is not possible for pharmacists to know this information on their fingertips as there are many drugs in the industry. Hence, it is left on the part of the manufacturer to provide it or the discretion of the user to discard using some signs.

There are so many information on this topic as to how to know when to discard an open drug or drug related product. They are all guidelines as many manufacturers have not produced these data or documents.

Let us use vitamin C tablets as an example. Vitamin comes in orange or white coloured tablets. On opening the cup containing many tablets, the drug is exposed to atmospheric air. After some time, depending on the relative humidity of the environment and how frequently the cup is open and how well it is closed, the colour of the tablet, be it white or orange begin to change. That is a sign of degradation of the tablet.

Read Also: In use shelf life of lonart or lokmal suspension

Very few manufacturers include some data on expiry date of the product after opening. It is supposed to read like 'no more than 90 minutes total opening time under 27°c and 90% relative humidity.' This way, users get an estimate of the expiry date after opening.

The national health service (NHS) provides us with a glimpse of what to do. According to them, tablets should not be used after 12 months of opening their container. However, this should not exceed the expiry date of the product. For example, a product is to expire 12/12/21 and was opened 12/4/21. A 12 months period will exceed the expiry date of the product. Hence, the product should be discarded after 12/12/21 even when it is not up to the 12 months period. But when the expiry date is 12/12/22, the product should be discarded after 11/4/22.

Even though many tablets can remain stable after many years in their original container under the right storage condition, the same cannot be said of the same product after opening. There is a strong possibility of mould that may grow on it.

Liquid dosage forms may not enjoy that long period of stability. This depends on the type of liquid, it's ingredients and storage conditions. Liquids made from volatile ingredients lose its stability anytime it is open. Those without or weak preservatives won't remain stable for long. Diluted liquids and liquids with high concentration of sugar are also prone to degradation before the stated expiry date.

Eye drops and ointment are generally given a five days expiry day period for multiple users (in cases of camps) or four weeks duration for single users. From personal experience, people who fail to heed to this advice end up re-infecting their eyes.

For ointments used for application to wounds and burns, the stability expected of the product is three months. For creams in jars, it is one month. However, ointment on tubes can enjoy stability up to six months duration unlike the three months given to creams in the same tube but unpreserved creams most likely only stay a month.

Read Also: Danger of taking expired drugs

Extemporaneous preparations are drugs freshly or recently prepared by pharmacists in their shop for use. British national formulary (BNF) frowns against mixing of medication with unlicensed vehicles or diluent. Example is mixing funbact A cream with body creams. This can decrease the bioavailability or adversely affects the stability of the cream. Stability is affected if there are no preservatives in the body cream/diluent (mixing both means the preservative in the cream has been diluted) or non compactible. Diluted ointment should be used within four weeks from the day it was mixed and creams are given two weeks. Extemporaneous preparation of ointment mixed with unverified diluent should not be used after eight weeks or four weeks for creams.

Creams are oil in water preparation. The water content is more than the oil. This makes it prone to degradation as microbial growth is easy. The in use shelf life is estimated to be two weeks. On the other hand, ointment is oil in water mixture. This means that the oil is more than the water. Oil is not suitable for microbial growth. Ointment can remain stable for up to four weeks in use.

Summary

Here is a summary of everything said so far.

Tablets And Capsules

1. Blister packed/single unit dose: use manufacturer's expiry 

2. Bulk packs: use within 1-year from date of opening 

2.1 Exceptions: products susceptible to atmospheric moisture, GTN 

Liquids 

1. With preservatives for internal and external use: use within 6-months (local policy may direct 3-months for 

internal liquids) 

2. Extemporaneous prepared to a BP monograph or EDS formula: use within 4-Weeks from date of manufacture 

3. Diluted Preserved liquids: use within 2-Weeks 

4. Preserved with Chloroform: use within 2-Weeks 

Creams 

1. Packed in Tubes: use within 3-months (local policy may direct 1-month for unpreserved creams) 

2. Packed in jars/pots: use within 1-month 

3. Diluted commercial preparations: use within 2-weeks 

4. Extemporaneous prepared in a suitable base: use within 4-Weeks from date of manufacture 

Ointments 

1. Packed in tubes: use within 6-months 

2. Packed in jars/pots: use within 3-months 

3. Diluted commercial preparations: use within 4-Weeks 

4. Extemporaneous prepared in a suitable base: use within 8-Weeks from date of manufacture

Note: The manufacturer's expiry, if shorter or the manufacturer's specified in-use shelf-life takes precedence over the following guidelines. The guidance given here should be used as aid to the pharmacist's own professional judgement on matters of stability and in-use expiry.