Since immunogenicity doesn't develop instantly, it's entirely possible he's developing it to the QSC batch now too. It started strong, gyno flared, and after a short while xx% of gh is now being inhibited, effectively lowering the dose.
Two other relevant factors:
~He stopped, then restarted using it. A "drug holiday" can trigger a stronger immune response when restarting vs "continuous exposure" to a peptide/protein. **
~Immune response is highly individual. He may just have a strong immune reaction to gh of all types.
Of course this is all hypothesis, and not only do we not have antibody test results, but usually, we don't have all the facts of what he's using, how he's using it, etc.
**on another note, I strongly suspect this is happening with GLPs. As the European Medicine Agency points out, the impact of immunogenicity (development of ADAs, Anti-drug Antibodies) is often not fully understood until some time, often years, after a peptide/protein therapeutic hits the market:
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