Drugs, Pharmaceutical Products, and Residual Solvents

Many solvents are in use in manufacture of drugs and pharmaceuticals (Table 4.1). The residual solvents are not completely removed by practical manufacturing techniques. The control of chemical impurities in drugs and pharmaceutical products has assumed significance in recent years. The presence of unwanted chemicals, even in small amounts, is known to influence the efficacy and safety of the drugs and pharmaceuticals. In view of this, the International Conference on Harmonization (ICH) 

Class 1 solvents comprise solvents to be avoided, including known carcinogens, suspected carcinogens, and solvents that cause hazards to the living environment (Table 4.2). 

Class 2 solvents are to be limited and include nongenotoxic animal carcinogens and others that induce irreversible toxicity like neurotoxicity and teratogenicity, and solvents suspected of other significant but reversible toxicities (Table 4.3). 

Class 3 solvents have low toxic potential. These solvents have no health-based exposure limits and have low levels of PDE of about 50 mg/day (Table 4.4). 

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