Biomedical subjects

Iva Pelosini

Publications and source records attributed to Iva Pelosini.

5 recordsLinked to original sources

PubMed2006

Experimental and clinical pharmacology of rifaximin, a gastrointestinal selective antibiotic.

Rifaximin (4-deoxy-4'-methylpyrido[1',2'-1,2]imidazo [5,4-c]rifamycin SV) is a product of synthesis experiments designed to modify the parent compound, rifamycin, in order to achieve low gastrointestinal (GI) absorption while retaining good antibacterial activity. Both experimental and clinical pharmacology clearly show that this compound is a non-systemic antibiotic with a broad spectrum of antibacterial action covering Gram-positive and Gram-negative organisms, both aerobes and anaerobes. Being virtually non-absorbed, its bioavailability within the GI tract is rather high with intraluminal and fecal drug concentrations that largely exceed the minimum inhibitory concentration values observed in vitro against a wide range of pathogenic organisms. The GI tract represents therefore the primary therapeutic target and GI infections the main indication. This antibiotic has therefore little value outside the enteric area and this will minimize both antimicrobial resistance and systemic adverse events. Indeed, the drug proved to be safe in all patient populations, including young children. The appreciation of the pathogenic role of gut bacteria in several organic and functional GI diseases has increasingly broadened its clinical use, which is now extended to hepatic encephalopathy, small intestine bacterial overgrowth, inflammatory bowel disease and colonic diverticular disease.

Animals↗

PubMed2006

Eradication of Helicobacter pylori: are rifaximin-based regimens effective?

Rifaximin is a non-absorbed semisynthetic rifamycin derivative with a broad spectrum of antibacterial activity including Gram-positive and Gram-negative bacteria, both aerobes and anaerobes. Although originally developed for the treatment of infectious diarrhea, the appreciation of the pathogenic role of gut bacteria in several organic and functional gastrointestinal diseases has increasingly broadened its clinical use. Being the antibiotic active against Helicobacter pylori, even towards clarithromycin-resistant strain, and being the primary resistance very rare, several investigations explored its potential use for eradication of the microorganism. Rifaximin alone proved to be effective, but even the highest dose (1,200 mg daily) gave a cure rate of only 30%. Dual and triple therapies were also studied, with the better results obtained with rifaximin-clarithromycin and rifaximin-clarithromycin-esomeprazole combinations. However, the eradication rates (60-70%) obtained with these regimens were still below the standard set by the Maastricht Consensus guidelines. Although rifaximin-based eradication therapies are promising, new antimicrobial combinations (with and without proton pump inhibitors) need to be explored in well-designed clinical trials including a large cohort of H. pylori-infected patients. The remarkable safety of rifaximin will allow high-dose regimens of longer duration (e.g. 10 or 14 days) to be tested with confidence in the hope of achieving better eradication rates. A drawback of rifaximin could be its inability to reach sufficiently high concentrations in the gastric mucus layer under and within which H. pylori is commonly located and this would likely affect eradication rate. Taking these considerations into account, bioadhesive rifaximin formulations able to better and persistently cover gastric mucosa, or combination with mucolytic agents, such as pronase or acetylcysteine, need to be evaluated in order to better define the place of this antibiotic in our therapeutic armamentarium.

Anti-Infective Agents↗

PubMed2006

Acid suppression therapy: where do we go from here?

The dramatic success of pharmacological acid suppression in healing peptic ulcers and managing patients with gastroesophageal reflux disease (GERD) has been reflected in the virtual abolition of elective surgery for ulcer disease, a reduction in nonsteroidal anti-inflammatory drug (NSAID)-associated gastropathy and the decision by most patients with reflux symptoms to continue medical therapy rather than undergo surgical intervention. However, a number of challenges remain in the management of acid-related disorders. These include management of patients with gastroesophageal symptoms who do not respond adequately to proton pump inhibitor (PPI) therapy, treatment of patients with nonvariceal upper gastrointestinal bleeding, prevention of stress-related mucosal bleeding, optimal treatment and prevention of NSAID-related gastrointestinal injury, and optimal combination of antisecretory and antibiotic therapy for the eradication of Helicobacter pylori infection. A number of new drugs are currently being investigated to provide a significant advance on current treatments. Some of them (namely potassium-competitive acid blockers (P-CABs) and CCK2-receptor antagonists) have already reached clinical testing while some others (like the antigastrin vaccine, H3-receptor ligands or gastrin-releasing peptide receptor antagonists) are still in preclinical development and need the proof of concept in human beings. Of the current approaches to reduce acid secretion, P-CABs and CCK2-receptor antagonists hold the greatest promise, with several compounds already in clinical trials. Although the quick onset of action of P-CABs (i.e. a full effect from the first dose) is appealing, the results of phase II studies with one such agent (namely AZD0865) did not show any advantages over esomeprazole. Thanks to their limited efficacy and the development of tolerance it is unlikely that CCK2 antagonists will be used alone as antisecretory compounds but, rather, their combination with PPIs will be attempted with the aim of reducing the long-term consequences of hypergastrinemia. While H2-receptor antagonists (especially soluble or over-the-counter formulations) will become the 'antacids of the third millennium' and will be particularly useful for on-demand symptom relief, clinicians will continue to rely on PPIs to control acid secretion in GERD and other acid-related diseases. In this connection, several new PPI formulations have been developed and two novel drugs (namely ilaprazole and tenatoprazole) are being studied in humans. The recently introduced immediate-release (IR) omeprazole formulation (currently available only in the USA) quickly increases intragastric pH and, given at bedtime, seems to achieve a better control of nocturnal acidity. IR formulations of other PPIs (including the investigational ones) will probably be available in the future and will enlarge our therapeutic armamentarium. Amongst the novel PPIs, tenatoprazole appears to be a true advance in the acid suppression therapy. Its long half-life (the longest among the available compounds) and longer duration of antisecretory action, with no difference between day and night, will allow the drug to go beyond the intrinsic limitations of currently available PPIs. Thanks to its favorable pharmacokinetics, the sodium salt of S-tenatoprazole is being developed and the preliminary results indicate that this drug has the potential to address unmet clinical needs. Although some decades have elapsed since the introduction of effective and safe antisecretory drugs in clinical practice and their use has stood the test of time, the ongoing research will further provide the clinician with more effective means of controlling acid secretion.

Anti-Ulcer Agents↗

PubMed2005

Rifaximin, a poorly absorbed antibiotic: pharmacology and clinical potential.

Rifaximin (4-deoxy-4'-methylpyrido[1',2'-1,2]imidazo- [5,4-c]-rifamycin SV) is a synthetic antibiotic designed to modify the parent compound, rifamycin, in order to achieve low gastrointestinal (GI) absorption while retaining good antibacterial activity. Both experimental and clinical pharmacology clearly show that this compound is a nonsystemic antibiotic with a broad spectrum of antibacterial action covering Gram-positive and Gram-negative organisms, both aerobes and anaerobes. Being virtually nonabsorbed, its bioavailability within the GI tract is rather high with intraluminal and fecal drug concentrations that largely exceed the minimal inhibitory concentration values observed in vitro against a wide range of pathogenic organisms. The GI tract represents, therefore, the primary therapeutic target and GI infections the main indication. The appreciation of the pathogenic role of gut bacteria in several organic and functional GI diseases has increasingly broadened its clinical use, which is now extended to hepatic encephalopathy, small intestine bacterial overgrowth, inflammatory bowel disease and colonic diverticular disease. Potential indications include the irritable bowel syndrome and chronic constipation, Clostridium difficile infection and bowel preparation before colorectal surgery. Because of its antibacterial activity against the microorganism and the lack of strains with primary resistance, some preliminary studies have explored the rifaximin potential for Helicobacter pylori eradication. Oral administration of this drug, by getting rid of enteric bacteria, could also be employed to achieve selective bowel decontamination in acute pancreatitis, liver cirrhosis (thus preventing spontaneous bacterial peritonitis) and nonsteroidal anti-inflammatory drug (NSAID) use (lessening in that way NSAID enteropathy). This antibiotic has, therefore, little value outside the enteric area and this will minimize both antimicrobial resistance and systemic adverse events. Indeed, the drug proved to be safe in all patient populations, including young children. Although rifaximin has stood the test of time, it still attracts the attention of both basic scientists and clinicians. As a matter of fact, with the advancement of the knowledge on microbial-gut interactions in health and disease novel indications and new drug regimens are being explored. Besides widening the clinical use, the research on rifaximin is also focused on the synthesis of new derivatives and on the development of original formulations designed to expand the spectrum of its clinical use.

Animals↗

PubMed2005

Rifaximin, a peculiar rifamycin derivative: established and potential clinical use outside the gastrointestinal tract.

Rifaximin is a poorly absorbed semisynthetic rifamycin derivative with a broad spectrum of antibacterial activity including Gram-positive and Gram-negative bacteria, both aerobes and anaerobes. Although originally developed for the treatment of infectious diarrhea, the appreciation of the pathogenic role of gut bacteria in several organic and functional gastrointestinal diseases has increasingly broadened its clinical use. The availability of a topical formulation (a cream containing 5% of the drug) and the lack of transcutaneous absorption pointed out in both animal and human studies has allowed its topical use in skin infections. Furthermore, since the spectrum of antibacterial action of rifaximin includes many organisms (e.g. Bacteroides bivius-disiens, Gardnerella vaginalis, Haemophilus ducreyi) causing genital infections, including Trichomonas vaginalis and Chlamydia trachomatis, its local application in the treatment of bacterial vaginosis (BV) has been attempted. Finally, since periodontal disease, caused by plaque (an aggregate of various bacteria), can be considered a 'local' infection, intrapocket rifaximin was tried in the treatment of periodontal infections. While the efficacy in pyogenic infections of the skin has been confirmed by several investigations, which showed an improvement of both subjective and objective parameters significantly better than that of the reference drug (i.e. chlortetracycline or oxytetracycline), the usefulness of rifaximin in BV and periodontal disease needs to be further studied in well-designed clinical trials.

Administration, Topical↗