Displacement of bilirubin from cord serum by sulphadimethoxine, amoxycillin, clavulanic acid in combination with either amoxycillin or ticarcillin, temocillin and cloxacillin

Experimental models assessing bilirubin neurotoxicity

The molecular and cellular events leading to bilirubin-induced neurotoxicity, the mechanisms regulating liver and intestine expression in neonates, and alternative pathways of bilirubin catabolism remain incompletely defined. To answer these questions, researchers have developed a number of model systems to closely recapitulate the main characteristics of the disease, ranging from tissue cultures to engineered mouse models. In the present review we describe in vitro, ex vivo, and in vivo models developed to study bilirubin metabolism and neurotoxicity, with a special focus on the use of engineered animal models. In addition, we discussed the most recent studies related to potential therapeutic approaches to treat neonatal hyperbilirubinemia, ranging from anti-inflammatory drugs, activation of nuclear receptor pathways, blockade of bilirubin catabolism, and stimulation of alternative bilirubin-disposal pathways.

Effect of drugs on cholesterol crystallization in an artificial bile model and relation of this effect to drug binding to albumin

Substances that can affect the crystallization of cholesterol from human bile and consequently the gallstone formation have been given considerable attention. We improved the model system for testing cholesterol crystallization-affecting activity (promoting or inhibiting) of substances and used it for some drugs that are excreted into bile. Besides other factors natural lipid-protein complexes isolated from the native human bile have been shown to be responsible for nucleation and fast crystal growth in cholesterol supersaturated model bile. Artificial lipid-protein complex of taurolithocholate, human serum albumin and Ca2+ (TLTC-HSA-Ca2+) exhibited a lower crystallization activity than both the artificial lipid-protein complexes of taurodeoxycholate, human serum albumin and Ca2+ and the lipid-protein complex isolated from native human bile. The model bile supplemented with this artificial lipid-protein complex (TLTC-HSA-Ca2+) formed a convenient system for testing of various substances (drugs) for their crystallization-affecting activity. From the 20 tested drugs, which could occur at least in small amounts in human bile, the highest crystallization-promoting activity was found for complexes with ampicillin, butorphanol and colchicine. Complexes with tetracycline, thioridazine and doxycycline were the strongest inhibitors. The drugs, which had some effect on cholesterol crystallization, affected somehow the artificial lipid-albumin complex by displacing its components. Interactions of different drugs with HSA and its artificial complexes with the conjugated bile salt and Ca2+ ions were followed by absorption spectroscopy to observe displacement interactions. On the basis of these experiments we could classify drugs into four groups which differ by their effects on spectral characteristics of complexes.

Disease-induced variations in plasma protein levels. Implications for drug dosage regimens (Part II)

Part I of this article, which appeared in the previous issue of the Journal, discussed the implications of variations in plasma protein levels in a number of diseases: hepatic and renal disease, acute myocardial infarction, burns, cancer, diabetes mellitus, hyperlipidaemia and inflammatory diseases. In Part II the authors continue their review with a further range of disease states, and consider their import for drug dosages.

Amoxicillin/clavulanic acid. An update of its antibacterial activity, pharmacokinetic properties and therapeutic use

Clavulanic acid enhances the antibacterial spectrum of amoxicillin by rendering most beta-lactamase-producing isolates susceptible to the drug. In clinical trials amoxicillin/clavulanic acid is clinically and bacteriologically superior to amoxicillin alone and at least as effective as numerous other comparative agents, such as orally administered cephalosporins, cotrimoxazole, doxycycline and bacampicillin, in the treatment of adults and children with the most common forms of infection encountered in general practice, i.e. urinary tract infections, upper and lower respiratory tract infections, otorhinolaryngological infections, and skin and soft tissue infections. It may also provide effective treatment for uncomplicated gonorrhoea, chancroid and gynaecological infections as well as acting as a prophylactic agent against surgical infection. Thus, in general practice environments where beta-lactamase production has restricted the effectiveness of amoxicillin, the combination of clavulanic acid with amoxicillin has clearly extended the usefulness of a tried and proven first-line antibacterial agent.

Clinical pharmacology of the perinatal period and early infancy

A consistent body of data, acquired in the last 20 years, indicates that at birth most of the physiological variables regulating drug kinetics are immature, thus conditioning modified kinetic profiles in the neonate. The situation may be greatly complicated by the possible 'in utero' exposure to agents capable of altering the activity of liver and/or kidney excretory functions, and/or the presence of severe pathological conditions capable of significantly altering regional or general haemodynamics. The different variables mature at different rates depending on the gestational age and physiopathological conditions. A review of the available information on drug kinetics in the neonate and early infancy is presented here. Therapeutic drug monitoring appears to be the only possible way to assure a safer therapy for at-risk populations.