Syrup bottles: PET, the 28 mm neck finish and the closure
A syrup bottle has the hardest life in the pharmacy. It holds a liquid for months, is opened morning and evening, and sometimes gets knocked over. Three choices make it reliable: its material, its neck, and the cap that screws onto it.
By Tecmom editorial team · 2 min read
A liquid asks more than a tablet
A tablet barely touches its bottle. A syrup wets the whole inner wall, for its entire shelf life. For the European Medicines Agency this is a difference in kind: its guideline on plastic packaging expects deeper extraction and interaction studies for liquid dosage forms than for solid ones.
Two things need to be known: what might pass from the plastic into the syrup, and what the plastic might take up from the syrup, a preservative or a flavour for instance. The results go into the medicine's file.
Why PET
PET has concrete strengths for these bottles. It is clear, so the level and look of the liquid can be seen, or amber when the active substance is light-sensitive. It is rigid, light, and does not break like glass. Its barrier properties, compared with HDPE and PP, are covered in our advice page HDPE, PET, PP.
The final choice remains the laboratory's, based on compatibility and stability studies run with its syrup.
The 28 mm finish, a neck that fits a whole family
A bottle neck is designated by its neck finish, the nominal diameter of the neck and its thread. In the Tecmom range, the PET syrup bottles from 60 to 500 ml share the same 28 mm finish. It is a practical choice: one cap model can cover a whole family of sizes, which simplifies purchasing and the filling line. See bottle neck finish.
The closure is part of the bottle
For the FDA, the cap of a syrup bottle is a primary component: it touches the liquid as soon as the bottle lies down. It must stay tight after dozens of openings, and the bottle and cap are qualified together as one system.
Depending on the medicine and the market, the closure adds other functions: a tamper-evident band that proves first opening, or a child-resistant mechanism. See the article on tamper-evident packaging.
In the Tecmom range
The catalogue lists PET bottles of 60, 90, 100, 150, 250, 300 and 500 ml with a 28 mm neck finish, two of them in amber PET, at 150 and 300 ml, as well as oval PET bottles. See pharmaceutical packaging.
A good syrup bottle goes unnoticed: it empties down to the last spoonful, closed every evening as on the first day. That is the result of a material chosen on evidence and a neck shared by a whole family.
Glossary
- PET
- Polyethylene terephthalate: the rigid, clear or amber material of syrup bottles.
- Neck finish
- The bottle neck and its thread, designated by their nominal diameter.
- Interaction study
- A study of what the packaging gives up to the product and what it takes up from it.
- Container closure system
- The container and its closure, qualified together as one whole.