In vitro and ex vivo effects of recent and new macrolide antibiotics on chemotaxis of human polymorphonuclear leukocytes

The effects of five macrolide antibiotics: erythromycin, josamycin, miokamycin, roxithromycin and rokitamycin, on human polymorphonuclear leukocyte (PMN) chemotaxis was studied in vitro and ex vivo. At therapeutic concentrations none of the antibiotics tested affected in vitro PMN chemotaxis. In vitro, erythromycin, josamycin, miokamycin, roxithromycin and rokitamycin decreased PMN chemotaxis significantly only at the concentration of 10 mg/l, which is not usually reached in vivo. Ex vivo studies after the ingestion of therapeutic doses of erythromycin, josamycin, miokamycin and roxithromycin by five volunteers showed a significant effect on PMN chemotaxis. However, further studies are needed to confirm and better evaluate the clinical significance of recent and novel macrolides on PMN chemotaxis.

Pharmacokinetics of rokitamycin after single administration to healthy volunteers

The pharmacokinetics of rokitamycin tablets were studied in 12 healthy volunteers in a randomized cross-over design. The doses tested were 200 mg, 300 mg, 400 mg and 600 mg, as single oral administration. Rokitamycin was absorbed quickly with Tmax for all doses around 30 min after drug intake. Total AUC and Cmax values were linearly related to the administered dose. The buffer formulation determined a low interindividual variation. The overall findings show a good similarity with the data obtained in Japanese subjects. Tolerability was very good.

[Study of intestinal absorption of calcium using 47Ca and whole body counter in renal calculosis with hypercalciuria]

Intestinal calcium absorption was studied using orally administered 47Ca and whole body counting. Using this method, we examined 82 patients suffering from recurrent calcium urolithiasis associated with idiopathic hypercalciuria, to evaluate the incidence of elevated intestinal absorption of this ion. An oral dose of 111 kBq (3 microCi) of 47Ca chloride, together with 250 mg of stable calcium as carrier, was given to each patient. Two hours and one week later, the total body radioactivity of each subject was measured. The retention of 47Ca, as percentage of the administered dose, was then calculated. The measurements were performed with a whole body counter consisting of a two-crystal moving system with shadow shield. Forty age-matched healthy volunteers were also examined. The whole body retention of 47Ca resulted significantly higher (p less than 0.0002) in the group of patients than in the control sample, whose m +/- SD was 22.0 +/- 6.0%. In particular, by defining the normality range as 10-34% (m +/- 2SD of control results), enhanced intestinal absorption of calcium was found in 28% of the examined patients. The use of this simple examination seems to be helpful in the physiopathologic assessment of subjects suffering from calcium urolithiasis and idiopathic hypercalciuria and consequently, in their appropriate management.

Intestinal calcium absorption in rheumatoid arthritis. A study using whole body counting

Conflicting results are reported in the literature concerning the changes in intestinal calcium absorption in rheumatoid arthritis (RA). In the present work, intestinal calcium absorption was studied in 27 postmenopausal women with RA, using whole body counting as the study method and orally administered Ca-47 as the tracer. Nobody was on corticosteroid therapy, but all received non-steroidal anti-inflammatory drugs and hydroxy chloroquine or gold compounds. The mean calcium absorption was 22.3% of the dose administered, with a standard deviation of 8.0%. The results obtained were not significantly different from those of 40 age- and sex-matched controls (mean +/- SD: 22.0% +/- 6.0%). Our findings seem to exclude the hypothesis of calcium malabsorption as one of the causes leading to osteoporosis in RA.

Temporal arteritis in seropositive rheumatoid arthritis with rheumatoid nodule

A 61-year-old woman, suffering from classic seropositive rheumatoid arthritis with rheumatoid nodule histologically documented, developed temporal arteritis. HLA-DR typing revealed the presence of DR3 and DR4 antigens. The findings from previous studies support the association of HLA-DR antigens, giant cell arteritis-polymyalgia rheumatica and rheumatoid arthritis, and suggest the participation of a common immunogenetic mechanism in their pathogenesis.