Journal of Antimicrobial Chemotherapy, Vol 41, 231-236, Copyright © 1998 by The British Society for Antimicrobial Chemotherapy
AF Goddard, PO Erah, DA Barrett, PN Shaw and RC Spiller
Delivery of amoxycillin across the human gastric mucosa to Helicobacter
pylori is poor compared with that of metronidazole and clarithromycin,
limiting the clinical effectiveness of this penicillin. To investigate the
physicochemical properties of penicillins that influence their flux across
gastric mucosa, the fluxes of metronidazole and eight penicillins were
measured in vitro across rat gastric mucosa. The lipophilicity of these
drugs was also measured using potentiometric titration. The mean fluxes of
monobasic penicillins (range 0.66-0.89 nmol/cm2/h) were significantly lower
than those of the aminopenicillins (range 1.94-2.80 nmol/cm2/h) (P <
0.005). Penicillin flux was not significantly correlated with lipophilicity
as measured, but was significantly correlated with published protein
binding data (rs = 0.9048, P < 0.002). Metronidazole flux was
significantly higher than that of any penicillin at 22.6 (+/-0.9)
nmol/cm2/h (P < 0.001). Therefore, the in-vitro gastric delivery of
penicillins can be predicted from protein binding which may in turn predict
activity against H. pylori in vivo.
ORIGINAL ARTICLES
The effect of protein binding and lipophilicity of penicillins on their in-vitro flux across gastric mucosa
Division of Gastroenterology, University Hospital, Nottingham, UK.
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