Penicillin concentrations in oropharyngeal and frontal sinus tissue following enteral and intravenous administration measured by microdialysis in a porcine model

Background

Penicillin may be administered enterally or intravenously for the treatment of bacterial infections within the oropharynx and the frontal sinuses. We aimed to assess and compare penicillin concentrations in oropharyngeal and frontal sinus tissues following enteral and intravenous administration in a porcine model.

Method

Twelve pigs were randomized to receive either enteral (0.8 g Penicillin V) or intravenous (1.2 g Penicillin G) penicillin. Microdialysis was used for sampling in oropharyngeal and frontal sinus tissues during a six-hour dosing interval. In addition, plasma samples were collected. The primary endpoints were time with drug concentration above the minimal inhibitory concentration (T>MIC) for two MIC targets: 0.125 (low target) and 0.5 (high target) μg/mL (covering Group A Streptococci, Fusobactarium necrophorum, Streptococcus pneumoniae and Hemophilus influenza) and attainment of these treatment targets for ≥50 % T>MIC.

Results

For both the low and high MIC targets, intravenous administration resulted in higher T>MIC in oropharyngeal and frontal sinus tissues compared to enteral administration. In oropharyngeal tissue, the treatment target (≥50 % T>MIC) was achieved for both the low target (96 %) and high target (68 %) when penicillin was administrated intravenously. In frontal sinus tissue, the treatment target was reached for the low target (70 %), but not the high target (35 %) when administered intravenously. None of the two tissues reached the treatment targets when penicillin was administered enterally.

Conclusion

Intravenous administrated penicillin in standard dosage is superior to enteral administration of penicillin in standard dosage in achieving clinically important T>MIC as the majority of targets were achieved following intravenously administration, while none of the targets were achieved following enteral administration. These results support the general notion of higher tissue concentrations following intravenous compared to enteral administration.