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The effect of incorporation of cloxacillin in liposomes on treatment of experimental staphylococcal mastitis in mice.

The effect of incorporation of cloxacillin in liposomes on the treatment of staphylococcal mastitis was assessed bacteriologically 18 h after treatment of experimental infections in mice caused by two strains of Staphylococcus aureus. Intramammary treatments were cloxacillin incorporated in liposomes, cloxacillin in combination with liposomes, empty liposomes, cloxacillin in saline and saline alone. In none of the experiments did entrapment of cloxacillin within liposomes enhance its antibacterial effects. Electron microscopic studies demonstrated the presence of liposomes in neutrophils which also contained staphylococci. The results support the hypothesis that intracellular staphylococci are metabolically dormant and therefore not susceptible to the action of inhibitors of cell wall synthesis such as cloxacillin.

Animals↗

Studies of interaction of a low-molecular-weight heparinoid (Org 10172) with cloxacillin and ticarcillin in healthy male volunteers.

Pharmacokinetic and pharmacodynamic interactions between Org 10172 (intravenous bolus injection of 3,250 anti-Xa units), which is a low-molecular-weight heparinoid, cloxacillin (500 mg orally four times daily for 3 days), and ticarcillin (4,000 mg intravenously four times daily for 2 days) were evaluated in two separate studies with healthy male volunteers (n = 18). Both cloxacillin and ticarcillin caused a significant increase in elimination half-life of anti-Xa activity, i.e., from 31 +/- 10 to 54 +/- 23 h and from 27 +/- 6 to 42 +/- 13 h, respectively (P less than 0.05). Ticarcillin decreased clearance (11%) and increased apparent volume of distribution (35%) (P less than 0.05), while for cloxacillin, these differences did not reach statistical significance. These changes in disposition of Org 10172 by the penicillins were not accompanied by important pharmacodynamic changes as evaluated by coagulation tests, platelet aggregation, and bleeding time. Cloxacillin appeared to influence blood coagulation (prolongation of the activated partial thromboplastin time and shortening of thrombin time; P less than 0.05) and facilitated thrombin-induced platelet aggregation, which coincided with a shorter bleeding time during the combined treatment in comparison with the time during treatment with Org 10172 alone (P less than 0.05). In conclusion, the disposition of Org 10172 was slightly changed by cloxacillin and ticarcillin, and, unexpectedly, cloxacillin appeared to have mild procoagulant effects.

Adolescent↗

Conversion of cloxacillin into a progressive inhibitor of beta-lactamases by sulfonation and its activity against various types of these enzymes.

On the assumption of the theory that the sulfone of a penam derivative should effectively act as a suicide substrate against beta-lactamases to which the parent compound is a poor substrate, the action of cloxacillin sulfone on four different types of beta-lactamases was studied. As we expected, cloxacillin sulfone showed strong mechanism-based irreversible inactivation against type Ib penicillinase and Proteus vulgaris cephalosporinase whereas it showed no progressive inactivation against cloxacillin-hydrolyzing type II penicillinase. However, an unexpected result was that cloxacillin sulfone could not inactivate Citrobacter freundii cephalosporinase which itself could hardly hydrolyze the parent cloxacillin. The number of hydrolytic events which occurred before inactivation of type Ib penicillinase, and P. vulgaris cephalosporinase, by the inactivator was 190 and 13, respectively. These values indicate that cloxacillin sulfone is far more effective as a suicide substrate against the two types of beta-lactamases than penam sulfones so far reported. The inactivation proceeded via the formation of an irreversible enzyme-inhibitor complex which could be detected by isoelectric focusing.

Cloxacillin↗

Topically applied benzathine cloxacillin for treatment of experimentally induced infectious bovine keratoconjunctivitis.

The efficacy of an ophthalmic ointment containing benzathine cloxacillin for treatment of infectious bovine keratoconjunctivitis was determined in 2 experiments. In the first experiment, Holstein calves (n = 6/group) were inoculated with Moraxella bovis and treated on postinoculation days 3 and 6 with either topically applied benzathine cloxacillin (250 mg/eye) or long-acting oxytetracycline formulation (20 mg/kg of body weight, IM). A third group of inoculated calves remained untreated as controls. For the second experiment, 4 groups of calves (n = 6/group) were inoculated and treated on postinoculation days 3 and 6 with 50, 125, 250, or 375 mg of benzathine cloxacillin; a fifth untreated group served as controls. Ocular specimens were obtained for microbiologic culture, and eyes were observed and assigned a clinical score daily. Eyes were photographed on alternate days. Ulcer surface area was measured, using a planimeter. In experiment 1, the week-2 ulcer surface area measurements for both groups of treated calves were smaller than those for controls. There was a greater frequency of M bovis isolation from the ocular secretions of controls than from those of benzathine cloxacillin-treated calves during postinoculation weeks 2 and 3. The number of M bovis isolations from the benzathine cloxacillin- and oxytetracycline-treated calves was not significantly different at any sample collection interval. On week 3, the scores of the benzathine cloxacillin-treated calves were smaller than those of controls. In experiment 2, calves of the 250- and 375-mg groups had smaller ulcer surface area measurements than did controls on week 2. By week 3, calves of the 375-mg group had smaller scores than did controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗

Clindamycin and cloxacillin compared in the treatment of skin and soft-tissue infections.

The subjects were 61 patients with skin or soft-tissue infections treated at the Cipto Mangunkusumo General Hospital in Jakarta, Indonesia. The patients, aged 15 to 59 years (40 females, 21 males), were randomly assigned to receive 300 mg of clindamycin or 500 mg of cloxacillin orally thrice daily for seven days. On day 8, the infections were cured in seven of the 31 clindamycin-treated patients and in three of the 30 cloxacillin-treated patients; on day 15, 27 of the clindamycin group and 18 of the cloxacillin group were cured; four clindamycin-treated patients and 11 cloxacillin-treated patients were improved; and one cloxacillin-treated patient failed. The between-group differences were not statistically significant. Pretreatment positive cultures were obtained in 40 patients, including Staphylococcus aureus in 24, group A beta-hemolytic streptococci in five, and a combination of S aureus and beta-hemolytic streptococci in four. Side effects were reported by three clindamycin-treated patients (gastric upset, nausea, and headache) and one cloxacillin-treated patient (nausea). Abnormal changes in laboratory test results from before to after treatment were noted in both patient groups and were probably not attributable to either drug. It is concluded that clindamycin is a safe and effective agent in the treatment of skin and soft-tissue infections.

Adolescent↗

Microbiological relevance and clinical potential of ampicillin-cloxacillin synergism.

Recent demonstration "in vitro" that combinations of ampicillin and cloxacillin, using concentrations at which neither were previously effective, will kill certain resistant Gram negative bacteria, has important clinical potential. We therefore studied 50 ampicillin resistant Gram negative rods cultured from septicemic patients for synergism. 7 of 23 E. coli strains with a minimal bactericidal concentration (MBC) of 128 microgram/ml were killed by combinations containing 4-32 microgram/ml ampicillin and 16-32 microgram/ml cloxacillin. These same strains were also resistant to cephalothin. Synergism was also noted in 1/4 strains of Enterobacter, 1/3 strains of Serratia, 5/14 strains of Klebsiella and 1/6 strains of Pseudomonas. In separate experiments ampicillin (56 mg/kg) and cloxacillin (14 mg/kg) was administered intravenously over a period of thirty minutes. Peak serum levels measured simultaneously at the end of the infusion were 235 +/- 11 (SEM) microgram/ml for ampicillin and 85 +/- 7 microgram/ml for cloxacillin. Levels of ampicillin/cloxacillin measured one and two hours after the infusion were 117/32 and 43/8 microgram/ml. T 1/2 of ampicillin and cloxacillin were 0.8 and 0.5 h respectively. Since the serum concentrations of both antibiotics measured one hour after the infusion were greater that levels required for "in vitro" synergism, we suggest that combinations of ampicillin and cloxacillin would be of importance in the treatment of Gram negative septicemia, since such therapy would increase the bactericidal effect of the sera without increasing the risk of toxic side effects.

Ampicillin↗

Dicloxacillin and cloxacillin: pharmacokinetics in healthy and hemodialysis subjects.

Differences in the elimination, distribution, and absorption of dicloxacillin and cloxacillin were studied in a group of healthy individuals with the use of a 2-compartment model. In patients on chronic intermittent hemodialysis, only dicloxacillin was investigated and the results were compared with data obtained in earlier studies on cloxacillin and flucloxacillin. In healthy volunteers the bioavailability after oral administration of 2 gm dicloxacillin or 2 gm cloxacillin amounted to 48.8% and 36.9% of the dose, respectively, when calculated from the area under the serum concentration-time curve, and to 74.1% and 48.5%, respectively, when calculated from the urinary excretion. Individual variation in bioavailability after oral administration was slightly lower for docloxacillin than for cloxacillin. The higher serum concentrations of dicloxacillin, as compared with cloxacillin, are also attributable to slower (renal) elimination (T 1/2: 42 and 33 min, respectively). Analysis of serum concentrations after intravenous administration of 1 and 2 gm dicloxacillin to healthy subjects revealed concentration-dependent kinetics with respect ot renal elimination. In hemodialysis patients the elimination rate of dicloxacillin (T 1/2: 129 min) corresponds with the extrarenal elimination rate in healthy subjects. The bioavailability after oral administration of 1 gm in patients is good (75.9% of the dose).

Administration, Oral↗

Drug distribution in whole blood of mothers and their newborn infants: studies of cloxacillin and flucloxacillin.

The distribution of cloxacillin and flucloxacillin in whole blood from seven newborn infants and their mothers was determined in vitro by equilibrium dialysis at 37 degrees C. Seven healthy, non-pregnant women of reproductive age served as controls. The distribution of the penicillins to erythrocytes was the same in the infants as in the adults. It was significantly lower in the presence of plasma albumin than when plasma was replaced by isotonic phosphate buffer. The plasma protein binding of cloxacillin and flucloxacillin in 22 infants was significantly lower than in the controls, but was slightly higher than in the mothers. A significant correlation between binding of cloxacillin and flucloxacillin in the same individual suggested that the two drugs were bound to similar sites. During the first postnatal week binding in infant plasma decreased. This change was correlated with an increase in the bilirubin levels. In the mothers, the binding increased during the first week after delivery. On the basis of the distribution data, maternal to fetal plasma and whole blood concentration ratios at equilibrium were calculated. These ratios were lower for flucloxacillin (medians 0.770 and 0.821, respectively) than for cloxacillin 0.996 and 1.094). Accordingly, at equilibrium somewhat higher levels of flucloxacillin should appear on the fetal than on the maternal side, whereas the concentrations of cloxacillin would be expected to be approximately the same.

Blood Proteins↗

Enhanced killing of penicillin-treated S. aureus by host defences: effects of amoxycillin, cloxacillin and nafcillin in vitro and in experimental mastitis.

The effects of pretreatment of Staphylococcus aureus with subMIC or 10 x MIC amoxycillin, cloxacillin and nafcillin on subsequent killing by bovine neutrophils or sensitivity to lysostaphin were examined in vitro, using penicillinase positive and negative strains. All penicillins increased the susceptibility of S. aureus to bovine neutrophils; with amoxycillin this was most marked with the penicillinase negative strain. Cloxacillin pretreatment was significantly more effective than nafcillin or amoxycillin in some tests and equally effective in others. The sensitivity of S. aureus to lysostaphin was increased following cloxacillin or nafcillin exposure. In a mouse model of mastitis, more cloxacillin and nafcillin-treated S. aureus (at 1/4 MIC) were killed than untreated bacteria 1 hr after infection but by 4 hr no differences were found. No differences were seen after intramammary infection with 10 x MIC penicillin-treated S. aureus. In glands with established chronic mastitis both cloxacillin and nafcillin at high doses failed to kill staphylococci. These findings indicate that prior exposure to penicillins increases staphylococcal susceptibility to killing by neutrophils but following phagocytosis, intracellular bacteria are protected from the lethal action of penicillins.

Amoxicillin↗

Determination of cloxacillin in milk and blood of dairy cows by high-performance liquid chromatography.

A rapid and sensitive high-performance liquid chromatographic method is described for the determination of cloxacillin residues in milk and serum. Only a clean-up step after deproteinization is necessary before the analysis. The chromatographic system involves the use of a C18 column and ultraviolet absorbance detection at 225 nm. The mobile phase was acetonitrile-0.02 M KH2PO4 (21:79) at pH 5. Recoveries for cloxacillin were 83.5 and 75.7% in serum and milk, respectively. Detection limits (10 ng/ml in milk and 50 ng/ml in serum) were below the stipulated European Union maximum residue limits for cloxacillin. Thus, the described method showed the same accuracy, precision and sensitivity as the microbiological assays but without interferences caused by other drugs commonly used in therapy. Analysis of different blood and milk samples obtained at different times from dairy cows treated with an intramammary dose of cloxacillin benzatine showed undetectable cloxacillin levels both in milk and blood samples.

Animals↗

Role of tolerance in cloxacillin prophylaxis of experimental Staphylococcus aureus endocarditis.

The role of tolerance was investigated in the prophylaxis of Staphylococcus aureus endocarditis with cloxacillin in rats. The effect of a single dose of 500 mg/kg, two 80 mg/kg doses 3 h apart, and a single dose of 80 mg/kg, alone or in combination with a single dose of 4 mg of gentamicin/kg, were compared for a tolerant strain of S. aureus and its isogenic nontolerant variant. At all dosages, cloxacillin was significantly less effective in preventing endocarditis with the tolerant strain than with the nontolerant variant. With the high dose of cloxacillin or two successive lower doses, nearly complete protection could be obtained against the nontolerant strain. However, for the tolerant strain, only the combination of cloxacillin and gentamicin afforded almost complete protection. For the tolerant strain, no serum bactericidal activity was found at the time of bacterial challenge after an injection of any dose of cloxacillin. These results suggest that the in vitro phenomenon of tolerance may have relevance in vivo.

Animals↗

FURTHER PHARMACOLOGY AND CHEMOTHERAPY OF CLOXACILLIN.

In concentrations greatly in excess of therapeutic blood levels cloxacillin has a slight hypotensive action. As with other antibiotics, it sometimes causes diarrhoea in rabbits but, in doses up to 200 mg/kg, it does not have a teratogenic effect on the rabbit foetus. Cloxacillin is distributed throughout the body. High concentrations are found only in the liver and kidney, these reflecting the high concentrations in the bile and urine respectively. It differs from other penicillins investigated in that there appears to be little or no renal tubular secretion as demonstrated in experiments on the hen. Cloxacillin is excreted as the unchanged drug and as an active metabolite in the urine and bile. After oral administration it is metabolized in the caecum giving a penicillin which differs from the urinary metabolite and which has a greater antibiotic action against Sarcina lutea than the parent penicillin. The activity of the caecal metabolite against resistant and sensitive strains of Staphylococcus, however, remains similar to that of cloxacillin. Against infections due to resistant and sensitive Staphylococcus in animals cloxacillin is active by both the oral and subcutaneous routes and it is more effective orally than an equal subcutaneous dose of methicillin.

Animals↗

Cloxacillin distribution in the rabbit eye after intravenous injection.

Distribution of isotopically labelled and intravenously injected cloxacillin was studied in rabbit eye. The antibiotic concentration determined by liquid scintillation counting proved to be a reliable measure of the total antibiotic concentration when controlled by microbiological assay. In the rabbit eye after an intravenous injection of 50 mg/kg of cloxacillin sodium, longlasting antibiotic concentration regarded as therapeutic against penicillinase producing staphylococci was obtained in all vascularized ocular structures and in the cornea. The antibiotic present in the iris and ciliary body, and in the retina and choroid preparations, proved to be partly intravascular, whereas it penetrated better into the extravascular tissue compartment of the sclera and limbal area. Cloxacillin failed to achieve a therapeutic antibiotic concentration in the vitreous body and in the lens. Administration of probenecid had an enhancing effect on ocular cloxacillin concentration allowing improved drug diffusion into the eye by means of an elevated plasma concentration. No specific ocular effect of probenecid was noticed. Therapeutic concentration of cloxacillin in the aqueous humour, otherwise barely achieved, was more satisfactorily obtained with a previous injection of probenecid.

Animals↗

Effect of paracentesis on ocular cloxacillin concentration.

The effect of anterior chamber puncture on cloxacillin concentration in the rabbit eye after intravenous injection was studied using a radioactive tracer method. The enhancement in drug concentration caused by paracentesis was most immediate and significant in the iris-ciliary body preparation. It was soon followed by high cloxacillin concentration in the aqueous humour, which contributed to elevated cloxacillin levels in the cornea, lens and anterior vitreous body, when compared to normal material. Contrary to normal eyes, cloxacillin concentration in the cornea of the punctured eyes was higher than in the limbal area. The morphological changes occurring after paracentesis are discussed. The breakdown of the hydrodynamic equilibrium in the eye, suggested as the only change after paracentesis by Raviola (1974), cannot merely explain the cloxacillin concentration changes measured in the punctured eye.

Animals↗

Concentrations of fusidic acid, cloxacillin, and cefamandole in sera and atrial appendages of patients undergoing cardiac surgery.

The concentrations of cefamandole, cloxacillin and fusicid acid were measured in the serum and heart tissue of 100 recipients of these drugs before cardiac surgery. During cardiopulmonary bypass, mean (+/- standard deviation) peak concentrations in serum of all patients were 63.0 +/- 34.0 micrograms of cefamandole per ml, 30.8 +/- 17.7 micrograms of cloxacillin per ml, and 32.4 +/- 10.8 micrograms of fusidic acid per ml. Mean (+/- standard deviation) concentrations in atrial appendages taken 1 h (+/- 15 min) after infusion were 21.3 +/- 11.0 micrograms of cefamandole per g, 23.8 +/- 17.3 micrograms of cloxacillin per g, and 10.7 +/- 4.2 micrograms of fusidic acid per g. No cloxacillin could be detected in 5 of 39 heart specimens. Mean tissue-to-serum ratios at 1 h for cefamandole, cloxacillin, and fusidic acid were respectively 0.35, 0.73, and 0.33. Fusidic acid, a drug which is highly effective in vitro against both methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis, was detectable in heart tissue in concentrations which were 12 times higher than the MICs of this agent against these resistant microorganisms.

Adult↗

Pharmacokinetic analysis of cloxacillin loss in children undergoing major surgery with massive bleeding.

To determine the magnitude of cloxacillin loss during surgical procedures involving significant blood loss and high fluid replacement, we compared the pharmacokinetics of cloxacillin in children during craniomaxillofacial surgery with the disposition of the drug in healthy young adult volunteers with intact circulation. Blood loss during craniofacial operations may exceed blood volume, in some cases by as much as three times. Hemodynamic replacement with electrolyte solutions and blood products, which do not contain the drug, further dilute cloxacillin concentrations. In the patients that we studied, mean drug loss was estimated at 71%. Cloxacillin concentrations in serum fell below the lower range of the MIC for Staphylococcus aureus during significant portions of the surgical procedures. Thus, the traditional dosing of cloxacillin during prolonged operations with massive blood loss is inadequate. A more frequent dosing interval or priming of all replacement fluids with the drug may be required to maintain therapeutic levels. Our findings suggest that massive blood loss is likely to have a dramatic effect on the level of any drug with a small distribution volume. If such a drug is essential to the patient's well-being (e.g., antibiotics, antiarrhythmics, and anticonvulsants), it must be replaced promptly.

Adolescent↗

Drug binding to plasma proteins during human pregnancy and in the perinatal period. Studies on cloxacillin and alprenolol.

Plasma protein binding of one acidic drug, cloxacillin, and one basic drug, alprenolol, was determined by equilibrium dialysis at +37 degrees C during pregnancy and the 1st postnatal week in 12 women and their newborn infants and in 7 nonpregnant women (controls). A significant increase in fraction free cloxacillin in maternal plasma occurred during pregnancy already from the 2nd trimester compared to the controls (p less than 0.01) and was most pronounced at delivery (median values 0.126 and 0.069, respectively). A similarly increased fraction free cloxacillin was found in cord blood (median value 0.108) which further increased during the 1st postnatal week (range 0.112-0.164). In maternal plasma the binding capacity returned to the values of the controls during the same time period. The binding of cloxacillin was significantly correlated with the concentration of albumin (p less than 0.01). High correlation was also found between binding of the basic drug alprenolol and concentration of orosomucoid (p less than 0.005). This was most obvious in the newborn infants with low concentrations (range 0.1-0.3 g/l) and in the mothers during the puerperium with high concentrations of orosomucoid (range 0.7-2.5 g/l). On the basis of plasma protein binding data in the mother and her child, a maternal to fetal plasma concentration ratio was calculated. For cloxacillin this ratio was close to unity (1.03), while it was significantly above unity for alprenolol (1.72). At equilibrium, therefore, the total plasma concentration of alprenolol in the mother can be expected to exceed the concentration in her infant.

Adolescent↗