Tris(hydroxymethyl)aminomethane (tromethamine, Tris) is an important organic chemical material. Tris is widely used in the pharmaceutical field, in addition to what we know as a component of buffers in biochemical experiments. For example, it is often used in eye drops. However, as people pay much attention to safety, they often have such a question: what kind of role does Tris play in eye drops? Is it safe for the user?

In general, Tris mainly plays two roles in the eye drops:

Adjusting the pH of the eye drops

Eye drops are one of the most commonly used pharmaceutical dosage forms for ophthalmic diseases. For many eye diseases, eye drops have a direct and rapid therapeutic effect. As the eyes have a special anatomical and physiological characteristics which made the corresponding requirements for the eye preparation: normal pH value of tear is 7.2~7.4, normal eye can withstand the pH range of 5.0~9.0 [1]. The pH value of the eye drops will directly affect the eye irritation and the effect of the drug, in the preparation of eye drops, buffers need to be added to adjust the pH value of the solution, so that it is similar with the tears to reduce the stimulus. At the same time, adjusting the pH also need to take into account the drug solubility, stability and other factors. Tris is a pH regulator commonly used in eye drops.

As active ingredient intermediate

As organic amine, Tris could react with insoluble drugs with acidic groups to form water-soluble complex salt, the most common Tris-containing eye drops is ketorolac tromethamine eye drops. Ketoacetic acid is a non-steroidal antiinflammatory drug for injection, ketorolac tromethamine can be dissolved in water, and stable in aqueous solution, with antipyretic analgesic and anti-inflammatory effects [2]. It inhibits the biosynthesis of prostaglandins by reversibly inhibiting cyclooxygenase and deoxygenase, thereby reducing the response of pain nerve to endogenous inflammatory factors, inhibiting peripheral nerve sensitization, and achieving the purpose of advanced analgesia. Ketorolac tromethamine eye drops are commonly used in inflammation and pain after ophthalmic surgery [3].

So, is it safe to contain Tris in eye drops?

Third, animal experiments and clinical studies have shown that [3], ketorolac tromethamine eye drops can significantly reduce corneal sensitivity, with a strong analgesic, anti-inflammatory effect, and no significant adverse reactions, it has the high safety.

In conclusion, Tris in eye drops is safe. However, although most of the eye drops are not prescription drugs, in principle, eye drops are not necessary to use. If there is eye discomfort, it is recommended to seek medical treatment timely to avoid the harm by the wrong use of drug.

References

[3] Zhu Guanghui, Wang Qizhi, Cai Caiqin, et al. Research progress in the use of NSAIDS in ophthalmology. Journal of Optometry, 2009, 11, 157-160.