Fibrinase is a commercial preparation containing the proteolytic enzyme serratiopeptidase (also known as serrapeptase). Serratiopeptidase has been traditionally used in several Asian and European countries for its anti-inflammatory and fibrinolytic properties. Its application in the context of sprains and soft tissue injuries is based on its purported ability to reduce swelling and promote the breakdown of fibrin, which accumulates in response to tissue injury and inflammation.

Scientific evidence for the use of serratiopeptidase (and thus Fibrinase) in the treatment of sprains is limited but does exist. Some small-scale clinical trials and animal studies have shown that serratiopeptidase can reduce swelling, pain, and inflammation more effectively than placebo and comparably to standard nonsteroidal anti-inflammatory drugs (NSAIDs). A few studies suggest that it may accelerate the resolution of edema and improve mobility in soft tissue injuries, including sprains. However, these studies are generally of moderate to low quality, with small sample sizes and methodological limitations.

Systematic reviews have concluded that while serratiopeptidase appears safe and may offer some benefit in soft tissue injuries, the overall quality and quantity of evidence are insufficient to make strong clinical recommendations. Thus, the use of Fibrinase for sprains is weakly supported by scientific evidence, with a need for larger, higher-quality studies to establish its efficacy and safety conclusively.