Montelukast dose selection in 6- to 14-year-olds: comparison of single-dose pharmacokinetics in children and adults

Montelukast, an oral leukotriene-receptor antagonist, has demonstrated efficacy and tolerability for the treatment of chronic asthma in adults. A once-daily 10 mg dose (film-coated tablet) was selected as the optimal adult dose based on dose-ranging studies. Asthma is a similar disease and is treated with the same medications in children and adults. These observations suggested that a dose of montelukast in children providing overall drug exposure (i.e., montelukast plasma concentrations) similar to that of the 10 mg film-coated tablet dose in adults would be efficacious, well tolerated, and obviate the need for separate dose-ranging studies in children. Therefore, the dose of montelukast for 6- to 14-year-old children was selected by identifying the chewable tablet dose of montelukast yielding a single-dose area under the plasma concentration-time curve (AUC) comparable to that achieved with the adult 10 mg film-coated tablet dose. Based on this approach, which included dose normalization of data from several pediatric pharmacokinetic studies, a 5 mg chewable tablet dose of montelukast was selected for use in clinical efficacy studies in 6- to 14-year-old children with asthma.

The effect of Helicobacter pylori eradication on intragastric pH during dosing with lansoprazole or ranitidine

BACKGROUND

The antisecretory effect of omeprazole on intragastric pH is decreased in the absence of Helicobacter pylori.

AIM

To investigate the effect of H. pylori eradication on intragastric pH during lansoprazole or ranitidine dosing in 41 asymptomatic H. pylori-positive subjects.

METHOD

Two groups of healthy H. pylori-positive volunteers were investigated. One group was dosed with lansoprazole 30 mg at 08.00 hours for at least 8 days, before and after 2 weeks of placebo-controlled double-blind eradication therapy using ranitidine bismuth citrate 400 mg b.d. and clarithromycin 500 mg b.d. The other group was dosed with ranitidine 300 mg at 23.00 hours for at least 8 days using the same trial design. An upper endoscopy was performed to establish H. pylori status by rapid urease test, culture and histology before both periods of dosing. Twenty-four hour intragastric pH recording was performed on the final day of all periods of dosing.

RESULTS

H. pylori eradication significantly decreased the intragastric pH reached during lansoprazole treatment throughout all periods of the day. Intragastric pH during ranitidine treatment was not affected by H. pylori eradication, except for the late-night period.

CONCLUSION

H. pylori eradication has a more pronounced effect on the acid-inhibiting properties of lansoprazole than on those of ranitidine.

A double-blind, placebo-controlled, parallel group study of oral trovafloxacin on bowel microflora in healthy male volunteers

BACKGROUND

Treatment with oral antibiotic drugs generally influences normal fecal flora. These changes can be both beneficial (eg, elimination of aerobic, gram-negative bacilli) and detrimental (eg, the appearance of resistant pathogenic micro-organisms). Trovafloxacin, a new fluoroquinolone with in vitro activity against anaerobes, and gram-negative, gram-positive, and atypical pathogens, is a potentially beneficial antimicrobial for bowel sterilization. This double-blind trial investigated the effect of trovafloxacin on the normal microbial bowel flora of healthy male subjects.

METHODS

Subjects were randomized (in a 2:1 ratio) to receive either 200 mg trovafloxacin once daily for 10 days or a matching placebo. Fecal samples were collected at two baseline occasions, on visit days 4, 7, 10, and 17, and at follow-up. Bacterial species were identified and quantified in the fecal samples.

RESULTS

Twelve subjects received the active drug and seven received placebo. No Enterobacteriaceae were found in samples from days 4 to 10 in subjects receiving trovafloxacin. No changes in Enterobacteriaceae were found throughout the study in subjects receiving placebo. Incidental Enterobacteriaceae were isolated from subjects in the trovafloxacin group at the end of the study. No clinically significant differences were found in either group with respect to prevalence, appearance, or disappearance of aerobic gram-positive cocci, anaerobic bacteria, or yeasts. All tested Enterobacteriaceae were highly susceptible to trovafloxacin. No increase in minimum inhibitory concentration values was seen in day 17 and follow-up samples for isolated Escherichia coli strains. No Clostridium difficile was found in day 17 or follow-up samples from subjects in the trovafloxacin group. All tests for clostridium toxin were negative.

CONCLUSIONS

During the treatment period, E. coli could not be cultured from the feces of the 12 healthy subjects receiving 200 mg trovafloxacin daily during days 4 to 10. All isolated Enterobacteriaceae were susceptible to trovafloxacin and no changes in susceptibility were found after the treatment period. In subjects treated with trovafloxacin, the prevalence and number of gram-positive bacteria were rapidly reduced. Trovafloxacin is able to selectively and reversibly suppress bowel flora.