Translation of a-t 2023; 54: 67
 

THERAPY FROM A CRITICAL VIEWPOINT

EVOTEARS for dry eyes - environmental compatibility questionable

Ursapharm advertises the medicinal product, EVOTEARS, as unique protection for dry eyes.¹ The eye drops contain exclusively (100%) perfluorohexyloctane, an alkane with a carbon chain that is completely fluorinated at one end and hydrogen-saturated at the other.² The drops are anhydrous, highly fluid (1 ml is equivalent to approximately 90 drops) and, according to the advertising, supposedly act like a protective coat over the tear.¹

In an eight-week phase II multicentre randomised study involving 336 patients with mostly evaporative dry eyes, i.e. caused by an unstable or deficient lipid layer, perfluorohexyloctane significantly reduces the primary endpoint, namely fluorescein corneal staining, which makes epithelial damage visible. Furthermore, symptoms such as stinging eyes and the incidence of dryness are improved.³ However, only physiological saline solution is used as the control instead of one of the usual aqueous tear substitutes such as hypromellose (e.g. ARTELAC), which can potentially relieve symptoms of all dry eye subtypes.⁴ Thus, the therapeutic value remains unclear. Tolerability is described as good, with less than 3% of instillation site reactions in both groups.³ The authors of the study - with the sponsoring company and two company employees directly involved in the design, data interpretation and manuscript editing - stress the importance of an improved tolerability profile compared to the standard treatments available, which up to 60% of patients allegedly discontinue within 12 months.³ However, we do not see any direct comparative studies of required duration to stake such a claim for the anhydrous eye drops. When asked, Ursapharm refers only to a small-scale study with no control group (45 subjects, 32 of whom [71%] were adherent),^5,6 which, in our opinion, cannot provide valid long-term data.

Perfluorohexyloctane is described as an inert and photostable compound that is neither absorbed nor metabolised.^7,8 It belongs to the substance group of perfluorinated and partially fluorinated alkanes comprising several thousand derivatives, which are also used for technical purposes. These can now be detected in the environment, in animals and in humans,^8,9 and are characterised as perpetual chemicals.¹⁰ Ursapharm, on the other hand, describes perfluorohexyloctane as neither toxic nor bioaccumulative based on ecotoxicological studies,⁵ but does not provide us with concrete environmental risk assessment data when asked to do so. The company merely refers to a 25-year-old guideline issued by the US Food and Drug Administration (FDA), which was used for approval in the USA.⁵

Dry eye is considered one of the most widespread ophthalmological diseases. Therefore, several million people could well be using tear substitutes containing perfluorohexyloctane in Germany alone.⁸ According to the ophthalmological literature, the sustainability of perfluorohexyloctane is in doubt. The substance has also been certified as an aid for intraocular surgery.² Given the lack of biodegradability of perfluorinated alkanes, there are calls to critically challenge the use of perfluorohexyloctane drops.^8,11

We advise against the use of this product until valid data on the efficacy and long-term tolarability of eye drops containing perfluorohexyloctane (EVOTEARS) in dry eye and on their environmental compatibility become available -Ed.

©  arznei-telegramm (Berlin/Germany), September 2023, protected by copyright laws.

Autor: Redaktion arznei-telegramm - Wer wir sind und wie wir arbeiten

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