Complex sentence: The breakdown products of tetracyclines are toxic and can cause Fanconi Syndrome a potentially fatal disease affecting proximal tubular function in the nephrons of the kidney, so prescriptions of these drugs should be discarded once expired.
Split into simpler sentences: The breakdown products of tetracyclines are toxic and can cause Fanconi Syndrome, a potentially fatal disease affecting proximal tubular function in the nephrons of the kidney. Prescriptions of these drugs should be discarded once expired.