The cumulative urinary excretion of sodium penicillin G following its oral and intramuscular administration is shown in Fig. 53-2. As much as 80%o of the intramuscularly administered dose may be recovered in the urine in less than 4 hours. Only about 20% is usually recovered following the oral administration of the antibiotic. with oral administration, this difference results from lack of absorption of much of the administered dose. Tkaeta ian], Na+ The inherent toxicity of penicillin as determined in animal experiments is extremely low. In several animal species the acute toxicity of penicillin is so low that death from overdosage has been attributed to the cation rather than to penicillin itself. Unfortunately, however, a significant percentage of the human population shows hypersensitivity reactions to penicillin. These reactions are of many different types, ranging from immediate anaphylactic reactions to late manifestations of the serum sickness type. It is believed that several hundred severe anaphylactic reactions have occurred following penicillin injections, many terminating fatally. ypersensitivity reactions are seen most often followingThe cumulative urinary excretion of sodium penicillin G following its oral and intramuscular administration is shown in Fig. 53-2. As much as 80% of the intramuscularly administered dose may be recovered in the urine in less than 4 hours. Only about 20% is usually recovered following the oral administration of the antibiotic. With oral administration, this difference results from lack of absorption of much of the administered dose. [ ],Na+ The inherent toxicity of penicillin as determined in animal experiments is extremely low. In several animal species the acute toxicity of penicillin is so low that death from overdosage has been attributed to the cation rather than to penicillin itself. Unfortunately, however, a significant percentage of the human population shows hypersensitivity reactions to penicillin. These reactions are of many different types, ranging from immediate anaphylactic reactions to late manifestations of the serum sickness type. It is believed that several hundred severe anaphylactic reactions have occurred following penicillin injections, many terminating fatally. Hypersensitivity reactions are seen most often following