Pharmaceuticals

Under ICH Q3C, Class 2 solvents carry individual limits in the drug product: methylene chloride 600 ppm, toluene 890 ppm, pyridine 200 ppm and chloroform 60 ppm. Class 3 solvents such as acetone, ethyl acetate and isopropyl alcohol have low toxic potential and are acceptable up to 5,000 ppm (0.5%) without further justification. Class 1 solvents such as benzene should be avoided. Choosing a Class 3 solvent where the chemistry allows makes residual solvent control simpler.

The Handbook of Pharmaceutical Excipients gives 0.25-5.0% w/w as the lubricant range, and most blends sit near the low end, around 0.5-1%, added last and mixed briefly. Too little and the blend sticks to punches and die walls. Too much, or mixing too long, coats particles with a water-repellent film that can soften tablets and slow disintegration and dissolution. Fix the level and blending time during development and hold them constant.

A pharmacopoeial grade (IP, BP, USP or Ph. Eur.) is made and tested to a monograph that fixes identity, assay, impurities and limits such as heavy metals or residual solvents, and is meant for use in medicines. A technical grade is specified only for industrial performance. The same chemical name can be sold in both, so state the grade on every enquiry. We confirm the grade and documents the producer can offer against your requirement before quoting.

Every batch should arrive with the manufacturer's certificate of analysis (COA), showing the batch number and results against the agreed specification, and a safety data sheet (SDS). For vendor qualification, QA teams usually also want a specification or TDS and samples to test at their own site. Lithionyx sends the manufacturer's COA and SDS with every batch, provides samples and TDS on request, and labels every pack with product, batch and hazard details for traceability.