A need for designing better closures for eye drops bottles

Ophthalmic solutions or eye drops are probably one of the most fast moving pharmaceutical products. You buy them to treat a variety of viral and bacterial eye infections, irritations, allergies and dry eyes. They are also used for treating eye injuries, before testing your eyes and before and after eye surgery. However, consumer complaints indicate that the quality as well as the design of closures used in containers of eye drops and even ear drops leave much to be desired. In fact, flawed closures have raised issues of safety and also economy of use, thereby calling for urgent intervention by the drug control authorities.

The container closure system, including the seal , the outer cap and the solution dispensing nozzle, play an extremely important role in maintaining the sterility of the solution within and preventing their contamination during use. So a good quality closure system not only has to ensure these, but also regulate the volume of the eye drops dispensed to prevent wastage and also ensure ease of use. It’s extremely important to ensure that the closures meet all these requirements.

Most of these closure systems consist of a cap covering the dispenser unit, with an attached seal ring or ‘tamper-evident’ seal at the bottom. When you first unscrew the cap, you automatically break the seal, thereby separating the ring from the cap. Sometimes this ring may break and fall off on its own. But most of the time , you have to remove the cap and then the ring, put the cap back and apply adequate torque, so that the spike underneath the cap pierces the dropper tip and makes a small hole through which the liquid comes out in drops.

Consumer complaints reveal that the biggest problem with this closure is the poor quality of the piercing mechanism. Sometimes either the barb is not sharp or long enough to pierce the nozzle or there is some cap tube misalignment that prevents the spike from making an aperture, thereby denying access to the medicine. What makes matters worse is the refusal of chemists to change such bottles on the ground that the consumer has broken the seal. What they fail to understand is that such bottles are defective and need to be replaced and the defect reported to the drug company and the regulator.

A consumer recently told me that in desperation, he tried to pierce a hole by heating a needle and plunging it into the tip of the nozzle. However, to his horror, the plastic melted from the heat and he was not sure if that had contaminated the solution- so he had to throw away the bottle. A defect such as this is a safety hazard, if the consumer is forced to pierce a hole, thereby contaminating the solution. This problem, from all accounts, exists in bottles that have closures without seals too.

Even where the spike works and makes an aperture in the nozzle, consumers say that they often have to use considerable force to twist and turn the cap and succeed only after several attempts. Considering that many senior citizens use several of these solutions following a cataract operation and may not have very strong or dexterous fingers, this is a very serious flaw and needs to be rectified. In fact the closure system needs to be simplified to ensure breaking of the ‘tamper evident’ seal and opening of the nozzle in one simple easy step.

Consumers also report on the variations in the way the dispenser releases the medication. While with some bottles, the drops fall in quick succession, wasting medication, and in some others, it is so slow that by the time it drops, you would have blinked and closed your eyes. The volume is also often much more than the eye can hold. Given the steep price of these medications, the drug control authority really needs to ensure that the bottle, the nozzle design and the size of the aperture ensure proper control over the volume as well as the speed of dispensation.

In fact, several studies around the world have focused on the need to reduce the drop volume of the medication, so as to bring down the cost, particularly for those on long term medication, such as glaucoma patients. A study on the topic published in the Journal of Advanced Pharmaceutical Technology and Research in 2011 ( Shiva Kumar et al) for example, concluded that “a drop size greater than 25 μL (microliter) will cause wastage of the medication and unnecessary expenses to the patient. Pharmacokinetic studies have shown that the maximal tear film concentration can be achieved with a drop of 20 μL. While increasing the eye drop’s size beyond this does not increase efficacy, reducing the eye drop’s size will decrease wastage.”

It’s time the drug regulator looked closely at these issues and ensured better quality of closures to ensure safety, efficacy and economy of use.