The complete write-up of the results and methods for the GS-441524 sample analysis can be found here
In addition to analytical chemistry results, it is important to also collect data to better understand treatment outcomes. I suggest using the FIPLog website that I created. This website helps folks track and monitor their injections and observations during the 84-day treatment period.
Summary
We tested 15 different samples of GS. This included several popular brands in current use, several older brands suspected of having issues, and several very new brands that do not have substantial clinical testing.
We compared each sample’s concentration and relative purity against a reference sample of known concentration. Results suggest that some brands are likely to have higher concentrations than advertised, while other brands have concentrations that may not meet the marketed concentration.
Summary Data
The following summary table can be used to help guide brand selection and dose estimation for individuals seeking to treat their cats for FIP.
Brands where multiple batches were tested appear to show higher variability than brands where only one batch was tested. Concentration estimates in the table show the 95% confidence interval for estimating the true concentration of a given sample. Brands with concentration estimates that fall outside of the marketed concentration at the low-end should be used with caution (increasing suggested doses), or avoided until additional testing can be completed.
| Brand | Measured Concentration (95% CI) | Marketed Concentration (mg/mL) | Likely to be in Spec? | # of Samples Tested |
| Ajax | 16.9 – 17.9 | 15 | Yes | 1 |
| BadShire | 7.4 – 8.9 | 15 | No | 1 |
| BEAT | 15.3 – 18.4 | 15 | Yes | 1 |
| Blossom | 6.3 – 8 | 15 | No | 1 |
| Brava | 17.3 – 19.6 | 15 | Yes | 1 |
| Capella | 16.3 – 19.4 | 15 | Yes | 2 |
| Hero_White_Cap | 13.8 – 15.5 | 16.5 | No | 1 |
| Mutian | 15.6 – 17.3 | 16.7 | Maybe | 1 |
| Pine_green | 13.4 – 15.8 | 15 | Maybe | 1 |
| Pine_red | 11 – 14.9 | 15 | No | 1 |
| Ruby | 15.1 – 18.5 | 15 | Yes | 1 |
| Shire | 13.4 – 14.6 | 15 | No | 1 |
| Spark_blue | 18.3 – 26.4 | 20 | Maybe | 1 |
| Spark_purple | 13.6 – 17.7 | 15 | Maybe | 3 |
| Spark_red | 20.3 – 26.4 | 17 | Yes | 1 |