The results of a novel prospective, randomised, observer-blinded study published in the journal BMC Anesthesiology showed that Chloroprocaine HCl at 40 mg and 50 mg doses had a longer resolution of the spinal block as compared to 30 mg dose. Nevertheless, a 30 mg dose leads to a greater secondary failure rate.

A total of 45 patients (in the age group 18 to 65 years; ASA score I-II) undergoing lower extremities surgery were studied to examine the time to total block resolution of chloroprocaine HCl 1% at 30, 40 and 50 mg intrathecal doses. Duration of these surgeries ≤ 40 minutes and with a requested dermatomeric level of nerve block ≥ T12. The patients were divided into three groups; Group 30 with 30 mg dose, Group 40 with 40 mg dose or Group 50 with 50 mg dose. The pharmacokinetic examination was made based on the venous blood and urine samples. As found, in Group 30, 40 and 50, the time to regression of blocks were 1.76 ± 0.35 hours, 2.13 ± 0.46 hours and 2.23 ± 0.38 hours, correspondingly. As compared to Group 40 and Group 50, the patients in Group 30 had a considerably quicker resolution of spinal block. Also, the 50 mg dose had a decreased time to readiness for surgery.