Age-associated pharmacokinetic changes of metronidazole

Serum concentration and urinary excretion of metronidazole were determined after p.o. administration of 500 mg to 15 young (20-25 years old) and 20 elderly (over 70) subjects. Serum levels were consistently higher and the AUCs were almost doubled in the aged group. One of the effects underlying the decrease in total clearance is the diminished renal excretion; however, the role of the reduction of distribution volume seems to be more important. Red cell binding of metronidazole significantly decreased in the aged group; this may also contribute to the reduction of distribution volume. Reduction of the standard dose of metronidazole by 30-40% is recommended in elderly patients.

Possible role of the control of arginase and methionine adenosyl transferase in the transport processes of endogenous formaldehyde and in hypermethylation

The authors believe the normal formaldehyde equilibrium in the organism to be governed by a biological control mechanism, which is thought to be closely connected to L - arginine and - indirectly - to the arginase enzyme. Arginine reacts with formaldehyde in a spontaneous equilibrium reaction yielding methylol - derivatives thus mobilizing formaldehyde. The methylol - derivatives of L - arginine were found in serum and urine. The authors assume the methylol - derivatives of L - arginine to have an inhibiting effect on cell - proliferation.

Uptake of metronidazole by human erythrocytes

In studies performed with equilibrium dialysis metronidazole was found to bind closely to human erythrocytes. In blood of haematocrit value approximately 50% of the drug was bound to erythrocytes. The ratio of bound and unbound metronidazole was influenced by the concentration of the drug and the erythrocytes. Of the intracellular proteins of erythrocytes it was the carbonic anhydrase enzyme in the first place which was responsible for binding; binding to haemoglobin was negligible. Besides binding to it, metronidazole reduced the carbonic anhydrase activity by almost 50%.

[Ultrastructure of pregnancy granuloma (angiogranuloma)]

The granuloma of pregnancy (angiogranuloma) has been studied by light-and electron microscopy. It has been revealed that granuloma of pregnancy consists chiefly of capillaries and undifferentiated connective tissue. It is a hyperplastic proliferative growth developing on the hormonal basis. In the case reported under the basement membrane presence of an electron lucent layer of fibrillar structure has been observed. Authors suppose that this phenomenon later will successfully be used in morphological differential diagnostics.