A further consideration in regard to drug shelf life concerns the form of the drug in question. For example is it liquid or powder as this too can effect its shelf life. For example, pills and capsules stored in their original, air-tight containers at cool room temperatures, free from humidity can be viable for around 10 years. This is much longer than the stated expiry date. The powdered form of a drug has similar longevity, especially if it is vacuum-packed (using a standard kitchen food vacuum-sealer) and kept in a cool place, away from the light. For drugs in liquid form, the shelf life is commonly shorter.
To determine if a drug has deteriorated, here are some common sense guidelines.
In the case of a liquid, the drug’s appearance is important. One should check its colour and clarity (has it become cloudy?); particulate matter (are there tiny visible particles?); preservative content (if stated); sterility (has the bottle been tampered with or opened?) and whether the drug has interacted with its enclosure (bottle or lid?). If none of these signs are present, then the liquid in question is more likely to be viable, than if there were any visible signs of degradation.
If the drug is in tablet form, signs of degradation include the tablet’s appearance, moisture content, hardness (has the tablet become as hard as a rock), friability (uncoated tablets), disintegration time (when placed in water) and uniformity of content. Again, any of these tell-tale signs may indicate chemical degradation.