Penicillin G - Procaine: blood levels and therapeutic action

Abstract

The authors, after emphasising the advantages of 1 injection every 24 hours penicillin therapy, present the results obtained with crystaline procaine - penicillin G in aqueous suspension ("Despacilina" Squibb). In a group of 10 patients (group I), both healthy and with dermatologic conditions, 300,000 units (1 ml) by intramuscular route provided, at the end of 24 hours, serum levels of 0,06 - 0.12 units in all the cases which had not received subsequent doses until the 24 hours period was completed. Maximum levels obtained with the administration of 300,00 units did not reach 0.20 in 6 cases, and in the other 4 cases a range of 0.20 to 0.85 was obtained. The authors had 3 cases of this group of 10 in which injection of 300,000 units were given every 12 hours; in these 3 cases, the maximum levels obtained were much higher than the maximum levels obtained with the single dose of 300,000 units. However, in these same 3 cases, when an injection was omitted, 80 that a period of 24 hours without injection was obtained, the blood levels at the end of 24 hours were just about the same as in those cases which had been given only 1 injection of 300,000 units. The results obtained in group II (4 patients in coma) suggest that oliguria is an important factor in maintaining high levels longer; on the contrary, forcing fluids provides a reduction of blood levels. In group III (7 cases of lobar pneumonia), the single dose of 300,000 units produced the complete cure of 6 cases, in as good a manner as was expected with the routine 'treatment (penicillin every 3 hours plus sulfadiazine); the seventh case, although presenting a typical fall of temperature 12 hours after the injection, showed the return of moderate degree of fever on the third day (37 to 38°C) and was subsequently given sulfadiazine plus penicillin 3/3 hours therapy. Even with this therapeutic program, evolution was not satisfactory and the cure was obtained only after 23 days. The serum levels obtained in this group were fairly satisfactory: all the cases in which levels were measured at the end of 24 hours (6 cases) had penicillin in the peripheral blood (0.06 - 0.16). In 4 out of 5 cases, the initial injection provided levels of 0.04 - 0.16 at the end of 36 hours. The significantly higher levels obtained in groups II and III, as compared with group I, are probably due to oliguria, consequence of restricted fluid intake or fever.