Adverse reactions following intravenous penicillin-G relate to degradation of the drug in vitro.

We have recently shown that high-dose intravenous therapy with penicillin-G always results in both sensitised lymphocytes and rise of anti-penicilloyl IgG antibodies. If penicillin-G is strictly given as freshly prepared bolus doses this sensitisation is prevented. In 193 patients, intravenous treatment with penicillin-G without special precautions (bolus doses stored up to 36 h at 4 degrees C or continuous infusions) led to 8.3% definite, 6.7% probable and 14.0% possible adverse reactions. In 116 patients treated exclusively with freshly dissolved doses, 0.9% definite, 1.7% probable and 4.3% possible reactions occurred. Whereas haemolytic anaemia (7) and neutropenia (12) were observed in 19 cases of the first group no such reactions were seen in the second group. Strict application of freshly prepared single doses prevents the majority of adverse reactions following highdose intravenous penicillin-G therapy. Degradation and transformation products formed in vitro are therefore the causative agents rather than the penicillin molecule itself.