How safety caps on medicines and detergents work

How many times have we tried to open a medicine and we failed on the first try? The truth is that usually these containers they are equipped with particular closing systems to avoid accidental opening and protect people from improper use of the contents. Neither there are different types: nowadays, we also find them in many household detergents or simply in e-cigarette liquids! In this article we will see together that technological devices have to ensure this additional security.

How Child-Proof Systems Work

These types of containers, more particularly the actual closing system (commonly called “caps“), They are called Child-Proof (CP) or Child-resistant (CR) packaging. In America they are actually also called Poison Prevention Packaging (PPP), returning to a more general meaning and less associated with the specific presence of children. In fact, although they were created to protect children under the age of 5 in particular involuntary ingestion of drugsthey are also used to avoid accidental opening of adult people but with difficulty perceiving dangerperhaps because they are elderly or subject to particular pathologies.

Baby medicine cap

Their first appearances date back to around 1800, although the first real introductions under specific regulations will wait another century or so and will be spurred by the ever-increasing number of children poisoned by improperly used drugs.

How many types of caps exist: the main types of closures and how they open

These systems are based on the principle that a child, under the age of 5, is unable to coordinate two or more separate actions to reach a safe opening. According to this project hypothesis, there are different types of systems.


System Press and Rotate

In this system, the container cap is actually made up of two coaxial caps, free to rotate independently. In this way, if you try to unscrew the cap, only the external one will rotate, not guaranteeing the opening of the container. If, however, pressure is applied first, then the two caps they join in the rotation through the presence of a groove widespread which introduces a relative constraint, so that a rotation of the external cap also corresponds to a rotation of the internal cap.

System Raise and Rotate

It is a system in which the relative constraint condition between the two coaxial caps occurs with grooves which are activated if the external cap is preliminarily raised. The operating mechanism is therefore similar to the previous one.

System Squeeze and Rotate

In this mechanism, an area that must be crushed is indicated outside the cap. Following crushing, the cap deforms and is able to rotate around the container. In this case, the initial mechanism is bound by the presence of two points of contact, integral with the container and the cap respectively, positioned at an angle of 90° from the crushing points. With the lateral crushing action, these contact points disappear, because the cap becomes deformed and takes them away from the rest condition, towards the outside. In this way, the cap no longer encounters obstacles to its rotation and can follow the helical path that allows it to be unscrewed.

The regulatory aspect

Child-proof openings cannot be created or developed independently, instead they require the satisfaction of particular technical requirements which are regulated by specific sector regulations. Some are to be considered in particular UNI regulations, including the UNI EN ISO 14375 of 2016, specific for packaging for pharmaceutical products. Each packaging is therefore subject to specific tests and must meet certain requirements to be placed on the market.

anti-opening caps

Some new frontiers

Recently, classic mechanical anti-opening systems – like those described so far – have been produced and partly marketed new biometric anti-opening systems, that is, equipped with a particular fingerprint sensor and recognition of the person who is trying to open the medicine. In this case, essentially the opening takes place in a controlled manner a priori, as only authorized people can actually open the package. This skimming can also take place via special dedicated applications, connected to a smartphone for example. It’s about technologies smart in fact, clearly limited for now to containers which for some extreme security reasons require raising the protection standards. In many cases, this system is also associated with automatic dosing of the drug.