www.lesswrong.com/posts/ZznBxPdZEB6ETeZvS/wth-is-cerebrolysin-actually
2 corrections found
the study in the lowest row of the chart is actually a systematic review, not a meta-analysis as the chart description claims.
This is incorrect. The cited 2013 Cochrane review is a systematic review that also includes meta-analyses; its abstract explicitly says "The meta-analyses revealed..."
Full reasoning
The post says the Chen et al. 2013 Cochrane review is "actually a systematic review, not a meta-analysis." But the review's own abstract directly contradicts that.
Cochrane labels the paper as a systematic review, and in the abstract's Main results section it explicitly states: "The meta-analyses revealed a beneficial effect..." In other words, it is a systematic review with meta-analyses, not a review lacking meta-analysis.
So the post's correction of the chart goes too far: the chart may be oversimplified, but calling the source "not a meta-analysis" is inaccurate.
1 source
- Cerebrolysin for vascular dementia - Chen, N - 2013 | Cochrane Library
Main results: "Six randomized controlled trials with a total of 597 participants were eligible. The meta-analyses revealed a beneficial effect of Cerebrolysin..."
Peptidases only function in acidic environments, so adding a strong base like sodium hydroxide is a common way to halt the degradation procedure.
This is biochemically incorrect. Many peptidases/proteases function best at neutral or alkaline pH, and sodium hydroxide is also commonly used in drug formulations simply for pH adjustment.
Full reasoning
The claim overgeneralizes protease chemistry in two ways.
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Peptidases do not only function in acidic environments. A basic counterexample is trypsin, a well-known protease/peptidase whose listed optimal pH is 7.5–8.5. That directly contradicts the statement that peptidases only work under acidic conditions.
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Sodium hydroxide is not used only to stop enzymatic degradation. FDA labeling and guidance documents explicitly describe sodium hydroxide as an excipient used for pH adjustment in drug products. So its presence in a formulation does not, by itself, show that it was added to halt peptidase activity.
Because both parts of the sentence are overstated, the inference drawn from sodium hydroxide's presence is not supported.
3 sources
- Trypsin - Worthington Enzyme Manual | Worthington Biochemical
Trypsin ... Optimal pH 7.5-8.5.
- BETHKIS (tobramycin inhalation solution) label
Inactive ingredients: sodium chloride, sulfuric acid, and sodium hydroxide (for pH adjustment).
- Considerations for Waiver Requests for pH Adjusters in Generic Drug Products Intended for Parenteral, Ophthalmic, or Otic Use | FDA
This guidance ... describes how FDA intends to evaluate a request for a waiver ... with respect to the pH adjuster(s).