A liquid excipient is added to a lock solution formulation containing a lower alcohol and an anti-coagulant, antibiotic, and/or anti-microbial, such as the ethanol and tri-sodium citrate lock solution formulation, to prevent citrate from crystallizing in catheters made from silicone. The locking solution could include a liquid excipient, such as glycerol, polysorbate-20, or polyethylene glycol (PEG)-400, along with a lower alcohol, such as ethanol, and an anti-coagulant, such as tri-sodium citrate, antibiotic, and/or anti-microbial.
