What is a drug Shelf life?
Shelf life is defined as the time period over which the concentration of the active drug ingredient in the formulation drops by 10 percent from its value at the time of manufacture.
The term “shelf life” of a drug slightly differs from a drug’s “expiration date.” The shelf life generally relates to a drug’s quality over a specified period of time, whereas the expiration date relates to both the quality and safety of a medication at a specific point in time.
Any medicinal product does not remain stable for all time. The potency or strength of the active ingredient drops over a period of time. Visually, formulations also change and become discolored, develop spots, becomes powdery, or show other distinct changes so the concern arises as to how long after manufacture the formulation can be used or in other words what is its shelf life.
The shelf life of medication depends on several environmental factors under which the finished product is stored.
Factors Affecting Shelf Life
The environmental factors which influence shelf life are:
- Exposure to air – oxygen present in the air can accelerate the oxidation of drug ingredients and shorten their useful life.
- Humidity – an increase in humidity levels leads to crust formation on tablets due to increased oxidation by air. Excess moisture also facilitates the growth of microbiological bacteria
- Light – certain compounds are sensitive to light and degrade on exposure. For this reason, such pharmaceutical products need to be stored in light-tight containers
- Microbial contamination – microbial contamination occurs due to unintentional exposure of the formulation to microbes present in contaminated environments
- The reaction of the active ingredient with excipients – excipients are added to active ingredients to improve their characteristics. However, care should be exercised in making the right combination so that they remain inert toward the active ingredient
- Temperature – decomposition of active drug ingredients takes place at a faster rate with rising in temperature
What is doxycycline?
Doxycycline is a broad-spectrum tetracycline-class antibiotic used in the treatment of infections caused by bacteria and certain parasites. It is used to treat bacterial pneumonia, acne, chlamydia infections, Lyme disease, cholera, typhus, and syphilis. It is also used to prevent malaria in combination with quinine. Doxycycline may be taken by mouth or by injection into a vein.
Doxycycline is in a class of medications called tetracycline antibiotics. It works to treat infections by preventing the growth and spread of bacteria. It works to treat acne by killing the bacteria that infects pores and decreasing a certain natural oily substance that causes acne. It works to treat rosacea by decreasing the inflammation that causes this condition.
Doxycycline was patented in 1957 and came into commercial use in 1967. It is on the World Health Organization’s List of Essential Medicines. Doxycycline is available as a generic medicine. In 2019, it was the 90th most commonly prescribed medication in the United States, with more than 8 million prescriptions.
How should doxycycline be used?
Doxycycline comes as a capsule, tablet, delayed-release tablet, and suspension (liquid) to take by mouth. Doxycycline is usually taken once or twice a day. Drink a full glass of water with each dose. If your stomach becomes upset when you take doxycycline, you may take it with food or milk. Talk with your doctor or pharmacist about the best way to take doxycycline. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take Doxycycline exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
Swallow the delayed-release tablets whole; do not split, chew, or crush them.
If you cannot swallow certain delayed-release tablets (Doryx; generics) whole, carefully break up the tablet and sprinkle the contents of the tablet on a spoonful of cold or room temperature (not hot) applesauce. Be careful not to crush or damage any of the pellets while you are breaking up the tablet. Eat the mixture right away and swallow without chewing. If the mixture cannot be eaten right away, it should be discarded.
Shake the suspension well before each use to mix the medication evenly.
If you are taking doxycycline for the prevention of malaria, start taking it 1 or 2 days before traveling to an area where there is malaria. Continue taking doxycycline each day you are in the area, and for 4 weeks after leaving the area. You should not take doxycycline for the prevention of malaria for more than 4 months.
Continue to take doxycycline even if you feel well. Take all the medication until you are finished unless your doctor tells you otherwise.
One doxycycline product may not be able to be substituted for another. Be sure that you receive only the type of doxycycline that was prescribed by your doctor. Ask your pharmacist if you have any questions about the type of doxycycline you were given.
What is the Shelf life for doxycycline?
Shelf life for doxycycline is around 4 years. This reflects the time period during which the drug is known to remain stable, which means it retains its strength, quality, and purity when it is stored according to its labeled storage conditions. Lots of doxycyclines that are tested and confirmed to be stable are eligible for a two-year expiration date extension. The FDA recently approved West-Ward doxycycline Hyclate 100-mg capsules eligible for use beyond the manufacturer’s labeled expiration date (August 7, 2020)
| Doxycycline Lot Number (West-Ward) | Manufacturer’s Original Expiry Date | New Use Date |
| August 7, 2020, Extension: | ||
| 68788A | March 31, 2015 | July 31, 2022 |
| GS008914 | March 31, 2018 | July 31, 2022 |
| GS008915 | March 31, 2018 | July 31, 2022 |
| GS008916 | April 30, 2018 | July 31, 2022 |
| GS008917 | April 30, 2018 | July 31, 2022 |
| August 22, 2018, Extension: | ||
| 68788A | March 31, 2015 | June 30, 2020 |
| GS008914 | March 31, 2018 | June 30, 2020 |
| GS008915 | March 31, 2018 | June 30, 2020 |
| GS008916 | April 30, 2018 | June 30, 2020 |
| GS008917 | April 30, 2018 | June 30, 2020 |
| September 3, 2015, Extension: | ||
| 65503A | August 31, 2012 | October 31, 2016 |
| 66058A | December 31, 2012 | October 31, 2016 |
| 66639A | April 30, 2013 | October 31, 2016 |
| 66648A | April 30, 2013 | October 31, 2016 |
| 69833A | March 31, 2016 | March 31, 2018 |
| 69834A | April 30, 2016 | April 30, 2018 |
Can doxycycline be used after the expiration date?
No, the safety of doxycycline beyond its shelf life or the expiration date cannot be guaranteed and it can also be risky and potentially harmful to the patient’s health. Not only is there the possibility that the medication is less effective, but there is also a chance that there has been the growth of bacteria or degradation of the drug that can lead to toxic effects.
Medications like doxycycline can easily become toxic after their expiration date and ingesting expired doxycycline has been shown to cause a dangerous syndrome that results in damage to the kidneys.
