Comparative bioavailability characteristics of commercial quinidine polygalacturonate and sulfate tablets

This study compared the relative bioavailability characteristics of quinidine polygalacturonate (QP) and quinidine sulfate (QS) after oral administration of commercial tablets and a liquid form prepared from crushed tablets in 13 healthy adult male volunteers. Each subject received the following four single-dose treatments in a randomized, crossover manner with a one-week washout period between treatments: 400 mg QS liquid, two 200-mg QS tablets, 550 mg QP liquid, and two 275-mg QP tablets. All four treatments were equivalent in terms of the dose of quinidine base. Multiple serum samples and two 24-hour urine specimens were collected over 24 and 48 hours, respectively, and assayed for quinidine with a specific HPLC assay method. For the absorption and disposition parameters measured (maximum serum concentration, time to reach maximum concentration, area under the concentration-time curve [0-48 hours], absorption and elimination rate constants, absorption and elimination half-lives, apparent total body clearance, apparent volume of distribution, and dose fraction excreted in the urine) no significant differences were observed for any of the parameters among the four treatments (p greater than 0.05). The results of the present investigation demonstrated that QP and QS produced identical serum quinidine concentration-time curves when given in the form of a tablet or liquid. The clinical implications of these observations with respect to the dosing of QP are discussed.

Disposition and toxicity of amphotericin-B in the hyperlipidemic Zucker rat model

The pharmacokinetics and toxicity of the lipophilic antifungal agent, amphotericin-B (AmpB), were studied in the hyperlipidemic obese rat model and compared with lean litter-mates. Serial blood samples were obtained for 36 h following a single intravenous infusion of AmpB (1.2 mg/kg) with pre- and post-drug measurements of renal function. Although triglyceride, cholesterol, HDL-cholesterol and LDL + VLDL-cholesterol levels were elevated in the obese compared with lean rats, protein: lipoprotein ratios were similar. There was a 2-fold increase in the area under the serum concentration-time curve of AmpB in obese rats compared to lean litter-mates (15,600 +/- 6900 v. 7800 +/- 2900 ng. h/ml; P less than 0.05); no differences in elimination rate constants were found between groups. Weight-corrected volume of distribution and total body clearance were significantly lower in obese compared with lean rats; no differences were found in absolute clearance or volume. Kidney levels of AmpB were markedly increased in obese versus lean rats. Similarly, kidney to serum ratios of AmpB were greater in obese compared with lean rats (152 +/- 113 v. 41 +/- 23; P less than 0.001). There was a significant decline in the creatinine clearance from baseline in the obese rats coupled with a rise in serum creatinine; no differences were found in lean rats. Similarities in absolute pharmacokinetic variables and protein: lipoprotein ratios suggest differences in AmpB disposition and toxicity are a result of differences in lipoprotein-mediated transport mechanisms between obese and lean rats.

[Study of the in vivo penetration of cotrimoxazole in alveolar macrophages]

Kinetic of cotrimoxazole was studied in serum, alveolar macrophages and BAL fluid from guinea pigs receiving sulfamethoxazole (SMX, 100 mg/kg) and trimethoprim (TMP, 20 mg/kg). Guinea pigs were killed by cervical dislocation 30 min, 1 h, 3 h, 6 h and 24 h after intraperitoneal injection. Lung lavage was performed to obtain alveolar macrophages and BAL fluid. TMP and SMX levels were assayed using high-performance-liquid chromatography. Highest SMX levels were obtained in serum at 30 min, in BAL fluid at 1 h and in alveolar macrophages at 3 h. Mean SMX/TMP ratios (30 min, 1 h, 3 h) was 26.5 +/- 0.8 in serum, 3.76 +/- 1.8 in BAL fluid and 1.15 +/- 0.02 in alveolar macrophages.

Pharmacokinetics of imipenem/cilastatin in neutropenic patients with haematological malignancies

The pharmacokinetics of imipenem/cilastatin were studied in febrile neutropenic patients with haematological malignancies. The peak plasma concentrations (36.4 +/- 4.96 mg/l), plasma half-life (60 min), volume of distribution (0.28 +/- 0.02 l/kg) and plasma clearance (3.23 +/- 0.38 ml/min/kg) were comparable with those in normal healthy volunteers suggesting that the drug handling is not appreciably altered in this group of patients. The administration of 12.5 mg/kg (max 1 g), 6-hourly achieved levels that were up to 3.5 times MICs of most relevant bacteria. The drug therefore has a potential use as empirical monotherapy in febrile neutropenic patients.

Steady plasma levodopa concentrations required for good clinical response to CR-4 in patients with 'on-off'

Ten patients with Parkinson's disease and severe motor fluctuations were given Sinemet (25/100) for 4 weeks followed by 4 weeks of Sinemet (CR-4). After each drug preparation was optimized, patients were rated by neurological examination and plasma levodopa (LD) measured at hourly intervals (9 a.m.-4 p.m.). For the group as a whole, variations throughout the day of plasma LD and clinical state were no different on the 2 formulations. Three patients whose fluctuations responded well to CR-4 had either much less variable plasma LD levels on CR-4 or were able to maintain plasma LD above a minimum threshold. In severe fluctuators, a major benefit from CR-4 can be expected only in those patients who can maintain steady plasma LD levels above the threshold for achieving the 'on' state.

Pharmacodynamic modeling of concentration-effect relationships after controlled-release carbidopa/levodopa (Sinemet CR4) in Parkinson's disease

Eight parkinsonian patients participated in a pharmacokinetic pharmacodynamic study of sequential doses of controlled-release carbidopa (CD)/levodopa (LD) at 4-hour intervals, with serial blood samples obtained before and after each dose. Effect measurements obtained with each blood sample included tapping and walking speed as well as a global assessment of motor function. Analysis of the data by extended least squares regression for linear, Emax, and sigmoid Emax pharmacodynamic models revealed that linear relationships do not provide the best fit between LD plasma concentrations and clinical effects after controlled-release CD/LD. The data are fit best to models that are curvilinear in nature. LD plasma concentrations greater than 2.0 micrograms/ml resulted in sustained effects on walking and global scores while the greatest rate of change in walking and global scores occurred at 0.9 micrograms/ml. LD plasma concentrations fluctuating around 0.9 micrograms/ml may result in the "on/off" effects seen in Parkinson's disease.

Pharmacokinetics of single-dose oral and intramuscular ketorolac tromethamine in the young and elderly

The elderly are likely candidates to receive analgesics for pain from a variety of etiologies. Ketorolac tromethamine is a nonsteroidal, analgesic, anti-inflammatory, antipyretic investigational drug with anti-prostaglandin synthetase activity. Sixteen healthy, young men (mean age 30 years and mean weight 75 kg) and 13 healthy, elderly subjects (11 men and two women; mean age 72 years and mean weight 75 kg) participated in an open-label, parallel single-dose study. On each day of ketorolac tromethamine administration the subjects fasted overnight and for 2 hours post-dose. A single intramuscular (IM) dose of 30 mg of ketorolac tromethamine was administered followed by an oral dose (PO) of 10 mg after a 1 week washout period for the elderly subjects. Plasma samples were taken from 0 through 48 hours post-dose and analyzed for ketorolac by HPLC. The elimination of ketorolac was decreased slightly in the elderly following both doses, as evidenced by a prolongation in half-life (4.7 to 6.1 hours for PO and 4.5 to 7.0 hours for IM) and a reduced total plasma clearance compared to the young adult subjects. These differences were statistically significant (P less than .001). Considerable overlap frequently was observed when comparing the range of values obtained for the young and elderly for plasma half-life, clearance, AUC, Tmax and Cmax. The absorption of ketorolac tromethamine was not altered substantially in the elderly following either dose route. Ketorolac plasma protein binding was not altered substantially in the elderly. The present results show that the elderly may need slightly less frequent dosing of ketorolac than young adults to maintain similar plasma levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors affecting penetration of retrograde coronary venous injections into normal and ischemic canine myocardium: assessment by contrast echocardiography and digital angiography

Ths experimental study described myocardial echo contrast enhancement through coronary venous injections. Retrograde administration of renografin was performed in 15 closed-chest dogs. Two-dimensional echocardiography was used to study myocardial echo contrast enhancement before and after coronary artery occlusion. Digital subtraction venography was used to assess delivery, drainage and shunting of the retrograde injectate. Systolic/diastolic blood pressure in the great cardiac vein measured 7 +/- 3/1 +/- 0.6 mm Hg and increased to 29 +/- 11/5 +/- 3 after coronary sinus occlusion and to 55 +/- 2.3/15 +/- 12 mm Hg during coronary sinus contrast injection. Myocardial contrast echo appearance in a midpapillary left ventricular short axis cross-section was limited to the anteroseptal region, extending to 28.4 +/- 11.3% of the section circumference after great cardiac vein injections and 35.3 +/- 17% after coronary sinus injections (difference NS). After occlusion of the left anterior descending coronary artery, great cardiac vein contrast injections resulted in opacification of 36.6 +/- 9.7% of the section circumference (N.S. vs preocclusion control) and opacified most, but not all asynergic segments. After occlusion of the circumflex coronary artery, myocardial echo contrast uptake was restricted to the septum and the anterior wall. The ischemic and asynergic posterolateral myocardial segments were not opacified. Digital subtraction coronary venography revealed rapid drainage of retrogradely injected contrast to the right atrium, in spite of coronary sinus balloon occlusion via venovenous anastomoses. Retrograde coronary venous contrast injections may help define myocardial regions which are accessible with retrograde coronary venous interventions.

Effect of time of dosing relative to a meal on the raft formation of an anti-reflux agent

Gamma scintigraphy was used in twelve healthy volunteers to establish whether the time of dosing of Liquid Gaviscon relative to a meal influenced its therapeutic action. Indium-113m labelled Liquid Gaviscon was administered to fasted subjects, 30 min after a technetium-99m labelled meal or immediately before ingestion of the meal. The time for 50% of the Gaviscon to empty from the stomach was 0.36 +/- 0.13 h, 3.10 +/- 0.31 h and 0.68 +/- 0.04 h (s.e.m.), respectively. The preparation was found to empty rapidly from the fasted stomach and could not be floated on a meal consumed subsequently. For raft formation to occur, Liquid Gaviscon should be taken 30 min after a meal.

EMLA cream in the treatment of post-herpetic neuralgia. Efficacy and pharmacokinetic profile

The analgesic efficacy of 5% of EMLA cream (5 or 10 g) when applied for 24 h periods was evaluated in 5 female and 7 male patients (mean age 69 years, range 50-85 years) with refractory post-herpetic neuralgia (PHN). Mean visual analogue pain intensity scores for all patients were significantly improved 6 h after application (P less than 0.05). In a subgroup of patients with facial PHN receiving EMLA cream, 5 g (n = 4), there were significant improvements in pain intensity scores at 6 h (P less than 0.05). 8 h (P less than 0.01) and 10 h (P less than 0.01) after application. Plasma lignocaine and plasma prilocaine concentrations were well below potentially toxic levels in all patients after application.

A double-blind study with placebo control of intramuscular ketorolac tromethamine in the treatment of cancer pain

The analgesic efficacy of ketorolac tromethamine was compared to placebo in 126 patients suffering moderate or severe chronic pain due to cancer in a double-blind parallel randomized study. Ketorolac was administered intramuscularly in doses of 10, 30 or 90 mg. Pain intensity and pain relief were assessed for 6 hours by scoring standard verbal scales and an overall assessment of the medication was given by the patients and the observer on completion of the study. Each dose of ketorolac was statistically superior to placebo for the sum of pain intensity difference (SPID) but no difference was seen between the three ketorolac regimens. When the ketorolac groups are combined, there was a significantly better pain relief as compared to placebo. The global evaluation scores were also statistically superior in the ketorolac groups combined than in the placebo group. A total of 15 patients reported minor adverse events, 10 being after ketorolac doses. This study shows that single intramuscular doses of ketorolac of 10 mg and above are effective in the relief of cancer pain, and are associated with a low incidence of side-effects.

Pharmaceutical design and development of a Sinemet controlled-release formulation

Many different formulation techniques are available for designing controlled-release dosage forms. Five different erosion-controlled or diffusion-controlled delivery systems were evaluated to select the 1 most suitable for Sinemet CR. The system ultimately selected, containing carbidopa-levodopa 50-200 mg, is a monolithic matrix tablet designed to have both of its active components released by surface dissolution and erosion. This system was found to be the most effective following extensive in vitro testing, pharmacokinetic studies, and clinical trials. Sinemet CR releases both carbidopa and levodopa by a 1st-order release rate. Controlled-release dosage forms of levodopa with slower in vitro release rates have lower plasma levels.

Rationale for continuous dopaminomimetic therapy of Parkinson's disease

Levodopa combined with carbidopa (Sinemet) remains the most effective approach to the symptomatic relief of Parkinson's disease. Over time, however, an increasing number of parkinsonian patients evidence motor response complications, notably abnormal involuntary movements and motor fluctuations. Clinical pharmacologic studies suggest that these phenomena may arise as a consequence of factors reflecting both natural disease progression and levodopa toxicity. Simple wearing-off responses appear primarily related to advancing degenerative changes afflicting the dopamine system. The appearance of peak-dose dyskinesias and complex, random motor fluctuations of the on-off type, on the other hand, may signal secondary postjunctional changes arising as a consequence of chronic intermittent excitation of postsynaptic dopamine receptors that are normally tonically stimulated. Therapeutically, prompt correction of wearing-off fluctuations can ordinarily be achieved by measures that deliver dopaminomimetics continuously to the central nervous system. In contrast, fluctuations of the on-off type initially persist despite stable circulating levodopa levels. With continuous levodopa treatment, however, the threshold for dyskinesias begins to rise and the dose-response relation shifts to the right; clinically, the severity of both dyskinesias and on-off fluctuations tends to diminish. It is thus tempting to speculate that the early and continuing treatment of Parkinson's disease with compounds providing a relatively constant level of central dopamine stimulation will preclude wearing-off phenomena and mitigate on-off fluctuations and severe dyskinesias.

Controlled-release carbidopa/levodopa (Sinemet 50/200 CR4): clinical and pharmacokinetic studies

Several controlled-release carbidopa/levodopa preparations have been formulated to achieve a more stable and extended antiparkinsonian action. The most effective is Sinemet CR (Sinemet CR4), with an erodible polymer matrix that retards release of levodopa. In 19 parkinsonians with prominent dose-by-dose fluctuations, double-blind crossover trials comparing 8-week regimens of standard carbidopa/levodopa (25/100) to Sinemet CR (50/200) showed comparable clinical outcomes, with mean daily dosing for optimal control reduced from 10.2 to 5.4 (although mean daily levodopa dosage increased from 1,340 to 1,781 mg/day). Most patients improved on the Sinemet CR regimen in hours "on" and in ratings of clinical state and disability. With pharmacokinetic studies correlated to clinical ratings, plasma levodopa was less variable during Sinemet CR treatment, and clinical responses showed greater uniformity. Compared to standard Sinemet 25/100, time to peak levodopa concentration (2.3 versus 1.1 hrs), onset of maximal clinical improvement (2.2 versus 1.1 hrs), and other indices were significantly delayed with Sinemet CR. Levodopa bioavailability and clearance were similar between formulations. Although onset of clinical response is slower, the Sinemet CR formulation lessens peak-dose and "wearing-off" responses occurring with conventional carbidopa/levodopa and offers substantial improvement for some parkinsonians.

Pharmacokinetics and bioavailability of Sinemet CR: a summary of human studies

The pharmacokinetics of Sinemet CR, a controlled-release formulation containing carbidopa and levodopa, were investigated in healthy young and elderly volunteers and in patients with Parkinson's disease. Sinemet CR produced more sustained plasma levels of levodopa, carbidopa, and 3-O methyldopa than did conventional Sinemet. In elderly subjects, the corresponding steady-state plasma levels fluctuated in narrower ranges with Sinemet CR than those following the administration of Sinemet. Results indicate a levodopa bioavailability of 71% for Sinemet CR, in contrast to a bioavailability of 99% for Sinemet for these subjects. The carbidopa bioavailability of Sinemet CR was 58% relative to that of Sinemet. Systemic decarboxylase inhibition was comparable between the 2 regimens as indicated by the renal clearance of levodopa. The absorption of levodopa was slower and more protracted with Sinemet CR than with Sinemet. Food increased the levodopa bioavailability of Sinemet CR. This increase was attributed to an increased gastric retention time. No dose-dumping occurred with Sinemet CR in either the nonfasting or the fasting state. Levodopa bioavailability was lower in young volunteers than in elderly volunteers. This was attributed to an age-related decrease in gastric emptying and in 1st-pass metabolic decarboxylation in the gastrointestinal (GI) tract. In parkinsonian patients, as in healthy subjects, the Sinemet CR formulation produced more sustained levodopa plasma levels. These patients required a higher total daily dosage of Sinemet CR than of Sinemet for control of parkinsonian symptoms, but less frequent dosing was required during chronic therapy. Peak plasma levodopa levels increased proportionately with increasing Sinemet CR dosage. These observations were consistent with the pharmacokinetic characteristics of the formulation.

Gastrointestinal transit of Sinemet CR in healthy volunteers

The gastrointestinal transit and systemic absorption of Sinemet CR (50/200) and standard Sinemet (25/100) have been studied in fasting and "fed" healthy human subjects. Both formulations were labeled with a gamma-emitting radionuclide, and their gastric emptying, colon arrival, and in vivo dissolution profiles were monitored using gamma scintigraphy. The standard dosage forms were found to disperse soon after administration and to empty rapidly from both the fasting and the "fed" stomach. The erosion of the controlled-release (CR) system was independent of food. Dosing after a light breakfast altered the gastric emptying profile of the CR formulation and led to significant differences in the plasma levels of levodopa.

A pharmacokinetic and pharmacodynamic comparison of Sinemet CR (50/200) and standard Sinemet (25/100)

Seventeen patients with advanced Parkinson's disease who had fluctuations in motor performance while taking standard Sinemet (STD) 25/100 underwent daylong pharmacokinetic and clinical observation studies while taking both STD and Sinemet CR, a new controlled-release formulation containing 50 mg carbidopa and 200 mg levodopa. During treatment with Sinemet CR, there was an increase in the interdose interval, a reduction in the number of medication doses taken each day, an increase in total "on" time, and a reduction in the number of "off" episodes. Total daily levodopa intake was greater with Sinemet CR, although the bioavailability of levodopa and carbidopa from the two preparations was equivalent. The variability in plasma levodopa levels was significantly less with Sinemet CR. The slower release of drug from Sinemet CR was reflected in a prolongation of the Tmax for levodopa and a prolongation of the interval from Tmax to the succeeding trough levodopa level. Clinically, peak antiparkinsonian effect occurred later and lasted longer with the CR preparation.

Pharmacokinetics of intravenous immunoglobulin in very low birth weight neonates

We studied the pharmacokinetics of single doses of intravenous immunoglobulin (IVIG) of 1000, 750 and 500 mg/kg administered to 21 neonates with birth weights from 750 to 1500 g. No adverse effects were detected. Mean pharmacokinetic values for the large, intermediate and small dose groups, respectively, were: elimination half-life, 19.6, 28.7 and 22.1 days; clearance, 5.2, 5.6 and 3.7 ml/kg/day; volume of distribution, 151, 255 and 130 ml/kg. Mean peak IgG concentrations in serum were 1826, 1476 and 1257 mg/dl for the large, intermediate and small dose groups, respectively. Mean IgG on post-infusion Days 1 to 28 were similar for the intermediate and small dose groups but were higher in the larger dose group. Both large and intermediate doses achieved larger increases in IgG over preinfusion values (delta IgG) than the small dose. The differences in delta IgG between the large and intermediate doses were less notable. The wide variability observed indicates that individualization of intravenous immunoglobulin dosage will be required in these patients.

Controlled-release carbidopa/levodopa (CR) in parkinsonian patients with response fluctuations on standard levodopa treatment: clinical and pharmacokinetic observations

The efficacy of an oral controlled-release preparation of carbidopa/levodopa (Sinemet CR 50/200 mg) was compared with conventional carbidopa/levodopa (25/250 mg) in an open-label study. Twenty patients with idiopathic Parkinson's disease and severe response fluctuations participated. At the end of 6 months of CR treatment, the major clinical benefits included improvement of disability, reduction in number of "off" periods (predominantly end-of-dose hypokinesia), and increase in percentage of "on" time. Although dosages of CR required for an optimal therapeutic response were not significantly higher compared with conventional levodopa, bioavailability significantly increased. Delayed onset of antiparkinsonian effect of CR, resulting from an increase of Tmax for levodopa, was one of the major patient complaints and required additional small amounts of standard levodopa in some patients.

Simultaneous determination of pyrimethamine and mefloquine in human plasma by high-performance liquid chromatography with ultraviolet detection

A rapid, sensitive and selective method was developed for the simultaneous determination of pyrimethamine and mefloquine, two of the active ingredients of Fansimef, in human plasma. The procedure involved extraction of the compounds and the internal standard nitrazepam from basified plasma with dichloromethane and chromatography on a C18 column (microBondapak, 300 X 3.9 mm I.D.) with acetonitrile-phosphate buffer as the mobile phase and UV detection at 222 nm. The limit of quantification was 10 ng/ml for both substances, using a 1-ml plasma specimen. The mean inter-assay precision was 2.8% for pyrimethamine and 4.7% for mefloquine up to 800 ng/ml. The practicability of the method was demonstrated by the analysis of more than 1200 plasma samples from several pharmacokinetic studies involving single-dose administration of Fansimef to both patients and volunteers.

[The effect of furanocoumarins on microsomal oxidation in the rat liver]

Puvalen and psoberan are inhibitors of monoxygenase enzyme system activity of the liver. Puvalen exerts the biphase effect on the system, so it may be referred to such classic inhibitors as SKF-525A and pyperonil butoxide. Psoberan does not exert the biphase effect on the monoxygenase system that is apparently connected with its negative action on biomembrane structure of hepatocytes. The results must be taken into consideration when patients are treated with psoralens.

Effects of combining Ledermix and calcium hydroxide pastes on the diffusion of corticosteroid and tetracycline through human tooth roots in vitro

A 50:50 mixture of a corticosteroid/antibiotic paste and calcium hydroxide has been used clinically as a root canal dressing agent. This study investigated the effect on the release and diffusion of the corticosteroid and antibiotic components of Ledermix paste when it was mixed with a calcium hydroxide-methyl cellulose paste. The release rates of the trace molecules were lower when the mixture was used compared with release from Ledermix alone. The results indicated that this combination of materials, when used a long-term intracanal dressing, was likely to be more effective than Ledermix alone.

Induction of aromatic-L-amino acid decarboxylase by decarboxylase inhibitors in idiopathic parkinsonism

We evaluated the effect of administration of L-dopa, alone or in combination with a peripheral decarboxylase inhibitor, on plasma levels of aromatic-L-amino acid decarboxylase (ALAAD). After single-dose administration of L-dopa plus benserazide (Madopar) in healthy subjects and in chronically treated patients with parkinsonism, plasma ALAAD followed for 2 to 3 hours fell, but returned to predosing levels within 90 minutes. Four groups of patients with idiopathic parkinsonism were studied during chronic treatment: Group I, no L-dopa treatment (n = 31); Group II, L-dopa alone (n = 15); Group III, L-dopa plus benserazide (n = 28); and Group IV, L-dopa plus carbidopa (Sinemet, n = 30). Plasma ALAAD 2 hours after dosing was normal in Groups I and II. ALAAD was increased threefold in Groups III and IV, suggesting induction of ALAAD by the coadministration of a peripheral decarboxylase inhibitor. In a study of 3 patients in whom L-dopa/benserazide was started, plasma ALAAD rose gradually over 3 to 4 weeks. Further detailed pharmacokinetic studies of L-dopa, dopamine, and ALAAD in plasma and cerebrospinal fluid are required to determine if the apparent ALAAD induction by a peripheral decarboxylase inhibitor may be related to the loss of clinical efficacy of combination therapy in some patients and how it is related to end-of-dose deterioration and on-off phenomena.

[Pharmacokinetic, bacteriological and clinical studies on imipenem/cilastatin sodium in neonates]

Pharmacokinetic, bacteriological and clinical studies on imipenem/cilastatin sodium (IPM/CS) were performed in neonates. The results were as follow: 1. A total of 27 patients consisting of 17 mature and 10 immature infants were treated with IPM/CS. Each dose was 20 mg/20 mg/kg, and it was administered 2 approximately 3 times daily, in a 1-hour intravenous drip infusion for 3 approximately 12 days. The clinical efficacy of IPM/CS in 10 patients with bacterial infections (2 with sepsis, 3 with suspected sepsis, 2 with pneumonia, 2 with urinary tract infection and 1 with acute omphalitis) was evaluated as excellent in all patients, with an efficacy rate of 100%. All 5 causative organisms found in 5 patients (Staphylococcus aureus in 1, Staphylococcus epidermidis in 1, Escherichia coli in 2 and Flavobacterium meningosepticum in 1) were eradicated. Among 27 patients administered IPM/CS, adverse reactions were observed in 2 patients. These were rash and diarrhea. As for abnormal laboratory test values, elevations of GOT and GPT were observed. 2. MICs of IPM against 14 clinical isolates (S. epidermidis 1, S. aureus 6, Streptococcus agalactiae 4, E. coli 1, Enterobacter cloacae 1 and F. meningosepticum 1) from neonatal patients with bacterial infections were examined. IPM showed good antibacterial activity comparable to that of cefotaxime against S. agalactiae; however, the activity against methicillin-resistant S. aureus was poor. 3. Serum levels of IPM and CS were investigated in a total of 22 patients consisting of 15 mature and 7 immature infants after 20 mg/20 mg/kg of IPM/CS was administered. IPM and CS produced peak serum levels at the end of the drip infusion. In mature infants, peak serum levels of IPM and CS were 31.8 micrograms/ml (17.1 approximately 59.0 micrograms/ml) and 59.9 micrograms/ml (35.6 approximately 99.0 micrograms/ml), respectively. In low birth weight infants, these were 25.0 micrograms/ml (16.8 approximately 41.8 micrograms/ml) and 55.2 micrograms/ml (33.8 approximately 82.4 micrograms/ml), respectively. Half-lives of IPM and CS were 1.0 approximately 2.7 hrs. and 0.9 approximately 7.4 hrs. in mature infants, and 1.6 approximately 3.0 hrs. and 1.3 approximately 9.7 hrs. in immature infants, respectively. Generally the longer half-lives were observed in the younger neonates. Serum levels of CS remained higher and half-lives of CS were longer than those of IPM. The pharmacokinetics in neonates were different from those in adults or children.(ABSTRACT TRUNCATED AT 400 WORDS)

Treatment of idiopathic parkinsonism with L-dopa in the absence and presence of decarboxylase inhibitors: effects on plasma levels of L-dopa, dopa decarboxylase, catecholamines and 3-O-methyl-dopa

The effect of levodopa (L-dopa), alone or in combination with a peripheral decarboxylase inhibitor (PDI), on plasma levels of aromatic-L-amino acid decarboxylase (ALAAD, = dopa decarboxylase), L-dopa, 3-O-methyl-dopa (3-OMD), dopamine (DA), noradrenaline, adrenaline and dopamine beta-hydroxylase has been studied. In healthy subjects and in patients with parkinsonism plasma ALAAD level fell after administration of L-dopa + benserazide, but returned to previous levels within 90 min. In a cross-sectional study blood was obtained, 2 h after dosing, from 104 patients with idiopathic parkinsonism, divided into four groups: no L-dopa treatment (group 1), L-dopa alone (group 2), L-dopa + benserazide (Madopar) (group 3) and L-dopa + carbidopa (Sinemet) (group 4). Plasma ALAAD, which was normal in groups 1 and 2, was increased 3-fold in groups 3 and 4, indicating that there was induction of ALAAD by the co-administration of PDI. Despite this induction of ALAAD, in groups 3 and 4, with half the daily L-dopa dose compared with group 2, plasma L-dopa and 3-OMD levels were 5 times higher, while plasma DA levels were not different. The DA/L-dopa ratio was decreased 5-fold in group 2 and 16-fold in groups 3 and 4 as compared with group 1. Neither 3-OMD levels nor 3-OMD/L-dopa ratios correlated with the occurrence of on-off fluctuations. In a longitudinal study of three patients started on Madopar treatment the induction of plasma ALAAD was found to occur gradually over 3-4 weeks. Further detailed pharmacokinetic studies in plasma and cerebrospinal fluid are required in order to elucidate whether the ALAAD induction by PDI may be related to the loss of clinical efficacy of combination therapy in some patients and how it is related to end-of-dose deterioration and on-off phenomena.

[Pharmacokinetic, bacteriological and clinical studies on imipenem/cilastatin sodium in neonates]

Pharmacokinetic, bacteriological and clinical studies on imipenem/cilastatin sodium (IPM/CS) were performed in neonates. The results obtained are summarized as follows. 1. Plasma levels and urinary excretion of IPM and CS sodium were determined in 7 neonates with ages between 7 and 26 days (gestation periods were 37 to 41 weeks and birth weights were 2,410 to 3,890 g) upon 1 hour drip intravenous infusion of IPM/CS at 10 mg/10 mg/kg, or 20 mg/20 mg/kg. Mean plasma concentrations of IPM reached their peaks at the end of infusion with levels of 12.7 +/- 3.0 micrograms/ml for the group given 10 mg/10 mg/kg, and 19.1 +/- 4.1 micrograms/ml for 20 mg/20 mg/kg. The concentration of IPM in plasma showed a dose-response to the 10 mg/10 mg/kg and 20 mg/20 mg/kg dosages. Concentrations decreased with half-lives of 1.87 +/- 0.71 hours and 1.97 +/- 0.21 hours for the low and the high dosages, and plasma levels at 8 hours after administration were 0.3 +/- 0.1 microgram/ml and 0.8 +/- 0.3 microgram/ml, respectively. Mean urinary recovery rates in 8 hours after administration were 37.6 +/- 11.8% and 26.8 +/- 17.2% for the low and the high dosages. While, mean plasma concentrations and mean urinary recovery rates of CS were higher than those of IPM, mean plasma half-lives of CS were similar to IPM. 2. IPM/CS was administered to 11 neonatal patients (with ages between 1 and 26 days) of various bacterial infections, and clinical effectiveness, bacteriological efficacy and adverse reactions were evaluated. Clinical efficacies in cases including 7 with acute pneumonia and 1 each with suspected septicemia, intrauterine infection, acute urinary tract infection and periproctal abscess were judged excellent in 10 and good in 1 case, and the efficacy rate was 100%. Causative organisms isolated from these patients included 3 strains of Escherichia coli and 1 strain each of Streptococcus pyogenes, Streptococcus agalactiae Enterococcus faecalis and Haemophilus influenzae. All the organisms were eradicated by IPM/CS, thus the bacteriological eradication rate was 100%. No adverse reactions were observed, but decreased platelet in 1 patient and increased GOT in 2 patients were found as abnormal laboratory test values. These changes, however were transient, and returned to normal after discontinuation of IPM/CS. It was concluded that the clinical results of IPM/CS are indicative of excellent efficacy, safety and usefulness of the drug in the treatment of infections in neonates.

Co-trimoxazole (sulphamethoxazole plus trimethoprim) peritoneal barrier transfer pharmacokinetics

The pharmacokinetics of co-trimoxazole (sulphamethoxazole plus trimethoprim) were studied in end-stage renal disease in patients undergoing treatment with continuous ambulatory peritoneal dialysis (CAPD) and free of peritonitis. Plasma and dialysate concentrations were monitored for 1 exchange after administration of a single oral or intraperitoneal dose of co-trimoxazole, and were fitted by a pharmacokinetic model that took into account the equilibrium nature of CAPD by including return from the peritoneum in oral studies and from the plasma in intraperitoneal studies. Clearances were calculated and compared by analysis of variance. There was a significant effect of direction of flow (p less than 0.01), plasma-peritoneal clearances being larger than peritoneal-plasma clearances for both drugs. In addition, there was a significant difference (p less than 0.0001) between sulphamethoxazole clearances and trimethoprim clearances, with the latter being greater in both directions.

[Pharmacokinetic and clinical evaluations of imipenem/cilastatin sodium in neonates and premature infants]

Pharmacokinetic and clinical studies on imipenem/cilastatin sodium (IPM/CS), a beta-lactam antibiotic of the carbapenem class and its renal dehydropeptidase-I inhibitor in a 1:1 ratio, were performed in neonates, premature infants and an infant. IPM/CS was administered intravenously to 4 neonates and 5 premature infants at a dose level of 10 mg/kg. Plasma levels and urinary excretion of IPM and CS were determined in 2 neonates and 2 premature infants after 30-minute infusion, and in 2 neonates and 3 premature infants after 1-hour infusion. Plasma and cerebrospinal fluid (CSF) concentrations of IPM and CS were determined in 2 cases with purulent meningitis with ages of 2 and 26 days and 1 with purulent meningitis/bacteremia with an age of 4 days. The drug was administered to a total of 31 patients with ages between 0 and 30 days, consisting of neonates, premature infants and an infant (24 suffering with various bacterial infections, 5 treated for prophylaxis of infections and 2 treated for aseptic meningitis diagnosed at the completion of therapy) by intravenous drip infusion in a mean daily dose level of 50.1 mg/kg in 2 to 4 divided doses for 9 days on the average. Clinical efficacy, prophylactic effectiveness and bacteriological response of IPM/CS were evaluated in 29 cases. Adverse effects and abnormal laboratory test results were examined in 31 cases including 2 drop-out cases. The results obtained are summarized as follows. 1. Plasma concentrations of IPM and CS after 30-minute infusion of the drug reached their peaks at the end of administration, and obtained values were 22.4 to 29.0 micrograms/ml for IPM and 26.3 to 34.6 micrograms/ml for CS, thus peak plasma levels of CS were a little higher than IPM. Plasma half-lives of IPM were 1.05 to 2.43 hours, and those of CS were 1.24 to 4.76 hours, and the half-life of CS tended to be longer than that of IPM. Drug concentrations in plasma after 1-hour infusion of IPM/CS reached their peaks at the end of administration and the levels of CS (25.7 to 32.0 micrograms/ml) were a little higher than those of IPM (20.8 to 23.9 micrograms/ml). Plasma half-lives of IPM were 1.40 to 1.63 hours, whereas those of CS were 1.51 to 2.90 hours. The half-life of CS tended to be longer than IPM. 2.(ABSTRACT TRUNCATED AT 400 WORDS)

[Chemico-physical property and bile acid binding capacity of several antacids]

Liquid alginate (Gaviscon) binds small amount of bile acids. At pH 7 its viscosity (at low shear rate) is higher than that of other antiacids. High viscosity reduces the diffusion rate of bile salts and glucose and this property can play a role in the treatment of gastro-esophageal and duodeno-gastric refluxes.

Pharmacokinetics of sulfadiazine/trimethoprim in neonatal male calves: effect of age and penetration into cerebrospinal fluid

Sulfadiazine (SDZ)/trimethoprim (TMP; 30 mg of SDZ/TMP/kg of body weight) was given IV to the same 6 male calves at 1, 7, and 42 days of age and to 2 additional calves at 7 days of age. Serum concentrations of SDZ and TMP were best represented by a 2-compartment open model, but in 42-day-old calves, CSF concentrations of both drugs were best represented by a 1-compartment open model with first-order input. Between 1 and 42 days of age, the elimination half-life (t1/2(beta)) of SDZ decreased from 5.7 to 3.6 hours, and total body clearance (CLtot) increased from 1.43 to 1.88 ml/min/kg; the area under the curve (AUC0----infinity) decreased from 291.5 to 225.4 mg/L.h. The distribution coefficient (Vd(area)/kg of body weight) decreased with age, changing from 0.72 to 0.59 L/kg, between 1 and 42 days of age. Therapeutic concentrations of SDZ in serum (greater than 2 micrograms/ml) were maintained for 24 hours in 1-day-old calves and for about 15 hours in 7- and 42-day-old calves. The elimination rate of TMP increased about 9-fold; t1/2(beta) was 8.4, 2.1, and 0.9 hours, respectively, at 1, 7, and 42 days of age. Other values also reflected an increase in TMP elimination rate with age: CLtot increased from 2.8 to 12 to 28.9 ml/min/kg, k13 increased from 0.336 to 0.654 to 1.664/h and AUC0----infinity decreased from 32.8 to 7.9 to 3.1 mg/L.h, respectively. Therapeutic concentrations (greater than 0.1 microgram/ml) were maintained for 15 hours, 8 hours, and about 6 hours in 1-, 7-, and 42-day-old calves, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Tissue concentrations and bioactivity of amphotericin B in cancer patients treated with amphotericin B-deoxycholate

We have studied amphotericin B concentrations in tissues of 13 cancer patients who died after having received 75 to 1,110 mg (total dose) of amphotericin B-deoxycholate for suspected or proven disseminated fungal infection. Amphotericin B concentrations were measured by high-pressure liquid chromatography (HPLC) and by bioassay, the latter being done on tissue homogenates as well as on tissue methanolic extracts. The fungistatic and fungicidal titers of the tissue homogenates were also tested against three strains of Candida albicans and one strain of Aspergillus fumigatus. Tissue concentrations of amphotericin B measured by HPLC varied with the tested tissues as well as with the total dose of amphotericin B-deoxycholate administered and ranged from 0.4 to 147.1 micrograms/g. A mean of 38.3% (range, 23.0 to 51.3%) of the total dose was recovered by HPLC from all of the tested organs. Bioassay of tissue methanolic extracts reached 58 to 81% of the concentration measured by HPLC, whereas only 15 to 41% was recovered from the homogenates. Overall, 27.5% of the total dose was recovered from the liver, 5.2% was recovered from the spleen, 3.2% was recovered from the lungs, and 1.5% was recovered from the kidneys. The median concentration in bile was 7.3 micrograms/ml, suggesting that biliary excretion could contribute to amphotericin B elimination to an estimated range of 0.8 to 14.6% of the daily dose. Fungicidal titers were seldom measured in tissues, but fungistatic titers were observed and were linearly correlated with amphotericin B concentration measured by HPLC. In conclusion, only a small proportion of the amphotericin B administered as amphotericin B-deoxycholate to patients seems diffusible and bioactive.

Phase I trial of trimetrexate glucuronate on a five-day bolus schedule: clinical pharmacology and pharmacodynamics

Trimetrexate glucuronate (TMTX), a nonclassical folate antagonist, has been evaluated clinically on several schedules. We have studied TMTX administered as an iv bolus for 5 consecutive days every 3 weeks in 35 patients with advanced solid tumors. Drug was given at doses ranging from 7.6 to 18.8 mg/m2. The maximal tolerated dose was 13.1 mg/m2 per day x 5 for patients without prior myelotoxic treatment and 7.6 mg/m2 per day x 5 for previously treated patients. Because of wide individual differences in drug tolerance, dose escalation in 25% increments is recommended for patients not experiencing toxic effects. The dose-limiting toxicity was neutropenia. Rash and mucositis were also significant. TMTX concentrations were measured 1 and 24 hours after each dose, and the data were fit by use of a one-compartment pharmacokinetic model. With this simplified sampling and modeling scheme, the mean total body clearance (+/- SD) of trimetrexate was 31 +/- 20 mL/min per m2 and the volume of distribution was 13 +/- 7 L/m2. Mean plasma concentrations 1 hour after a dose were 1.12, 2.43, 3.33, and 3.25 mumol/L at 7.6, 9.1, 10.9, and 13.1 mg/m2, respectively. The mean TMTX concentration (+/- SD) 24 hours after a dose was 114 +/- 87 nmol/L. The mean area under the concentration-versus-time curve at 13.1 mg/m2 was 2,266 mumol.min/L. The drug concentration 1 hour after the first dose and the area under the concentration-versus-time curve were highly correlated with leukopenia and thrombocytopenia (r = .6 and .65 and P = .0007 and .0001, respectively). The maximal tolerated dose on the daily x 5 schedule was 30% of the dose tolerated on an iv bolus schedule. The choice of drug schedule for clinical trials when murine and human pharmacokinetics differ is discussed. Phase II trials are under way with both the iv bolus and the daily x 5 schedules.

The excretion of ketorolac tromethamine into breast milk after multiple oral dosing

We have studied the transfer of the analgesic ketorolac tromethamine into breast milk in ten women aged between 22 and 35 years. Ketorolac administration was started between 2 and 6 days after delivery. The breast milk was not fed to the infant because of maternal antibiotic use (6 patients) or because of jaundice of the baby. 10 mg of ketorolac was given four times daily for two days. Plasma and milk samples were collected on the two dosing days and on the first day after dosing. The plasma and milk were assayed for ketorolac concentrations by HPLC: the quantification limits were 10 ng.ml-1 and 5 ng.ml-1 respectively. The maternal plasma concentrations were within established ranges for ketorolac. In four patients the concentration of ketorolac in the milk was never above 5 ng.ml-1. At 2 h after dosing on both Days 1 and 2 there were quantifiable concentrations of ketorolac in the milk. The range was 5.2 ng.ml-1 to 7.9 ng.ml-1. The ratio of breast milk: plasma concentrations of ketorolac ranged from 0.015 to 0.037. The maximum potential amount of ketorolac that an infant may be exposed to daily could range from 3.16 mg to 7.9 mg, assuming a consumption of between 400 ml and 1 l of breast milk. On a weight-adjusted basis this is equivalent to between 0.16% and 0.40% of the total daily maternal dose.

Pharmacokinetics of ketorolac and p-hydroxyketorolac following oral and intramuscular administration of ketorolac tromethamine

Ketorolac tromethamine (KT), a potent analgesic with cyclooxygenase inhibitory activity, was administered in an open, randomized, single-dose study of Latin-square design to 12 healthy male volunteers. Doses of 30 mg oral (po) and 30, 60, and 90 mg intramuscular (im) KT were administered in solution. Plasma samples were analyzed for ketorolac (K) and its inactive metabolite, p-hydroxyketorolac (PHK), by reversed-phase high-performance liquid chromatography (HPLC). The 30-mg im dose was found to be similar to the 30-mg po dose with respect to total AUC values for both K and PHK. The amount of PHK circulating in plasma was very low as judged by AUC ratios (PHK/K x 100) of 1.9 and 1.5% for the 30-mg po and im doses, respectively. The rate of absorption of K and formation of PHK, as determined by Cmax and Tmax values, was significantly slower following the im doses. Total AUC and Cmax for K and PHK increased linearly with dose after im administration of 30, 60, and 90 mg of KT. The mean plasma half-life of K was remarkably consistent between po and im administration and was independent of dose, ranging from 5.21 to 5.56 hr. The plasma metabolic profile was similar following both routes of administration and graded im doses.

Clinical and pharmacokinetic evaluation of controlled-release levodopa/carbidopa (CR-4) in parkinsonian patients with severe motor fluctuations: a six month follow-up study

The results of a six month open-label study comparing the efficacy of controlled-release levodopa-carbidopa (Sinemet CR-4 200 mg/50 mg) with standard levodopa/carbidopa (250 mg/25 mg) in 17 patients with idiopathic Parkinson's disease and severe response fluctuations, are reported. Major clinical benefits included; improvement of disability, reduction of the number of 'off' periods (predominantly end-of-dose hypokinesia) and a slight increase in 'on' time. No improvement was observed in two of our patients. Mean levodopa plasma levels were comparable between the two types of formulations during optimal treatment, however systemic bioavailability was significantly higher with CR-4. Delayed onset of antiparkinsonian effect of CR-4, resulting from an increase of Tmax for levodopa, was one of the major complaints and required additional small amounts of standard levodopa in three patients.

A phase I trial of trimetrexate glucuronate (NSC 352122) given every 3 weeks: clinical pharmacology and pharmacodynamics

Trimetrexate glucuronate (TMTX), a non-classic folate antagonist, has been evaluated clinically on several schedules. We studied TMTX given as an i.v. bolus over 5-30 min every 3 weeks in 44 patients with advanced solid tumors; it was given at doses ranging from 20 to 275 mg/m2. The maximal tolerated dose (MTD) on this schedule is 220 mg/m2, which we also recommend as a starting dose for phase II studies in patients without extensive prior therapy. Because of wide individual differences in drug tolerance, dose escalation in 25% increments is recommended for non-toxic patients. The principal dose-limiting toxicity was myelosuppression, although in some patients a flu-like syndrome precluded dose escalation. Significant rash and mucositis also frequently occurred in toxic patients. TMTX plasma concentrations were measured after the first dose and the data were fit by two- or three-compartment mammillary pharmacokinetic models. The TMTX clearance rate was 36.5 +/- 21 ml/min per m2 and did not change with dose; non-linearities with increasing dose were apparent in the steady-state volume of distribution (Vss) and in the terminal disposition half-life (t1/2). The difference between pre-treatment and nadir leucocyte counts was correlated with TMTX dose (r = 0.58; P = 0.0006) and with the area under the concentration vs time curve (AUC) (r = 0.41; P = 0.02). Pre-treatment plasma albumin concentrations correlated weakly with the nadir white blood count (r = -0.36; P = 0.047). Optimal schedules for the administration of TMTX have not been established and phase II trials using both bolus and daily X 5 schedules are under way.

Pharmacodynamic evaluation of ofloxacin and trimethoprim-sulfamethoxazole in vaginal fluid of women treated for acute cystitis

Vaginal colonization with Escherichia coli is an integral step in the development of acute cystitis, and persistent vaginal coliform colonization may also be a predisposing step to recurrent urinary tract infections. For this reason, we evaluated antibiotic concentrations in the vaginal fluid, serum, and urine and the vaginal colonization by E. coli of 56 women receiving either ofloxacin (200 mg orally twice a day) or trimethoprim-sulfamethoxazole (TMP-SMX) (160/800 mg orally twice a day) for the treatment of acute cystitis. Ofloxacin and trimethoprim both penetrated into vaginal fluid to a considerably greater extent than sulfamethoxazole. Among 33 patients given ofloxacin, the concentration of the drug in vaginal fluid during one dosage interval ranged from 1.6 to 21.6 micrograms/ml. In 21 women given TMP-SMX the range of drug concentrations in vaginal fluid was 2.6 to 32.5 micrograms/ml for TMP and 1.0 to 6.2 micrograms/ml for SMX. Treatment with both ofloxacin and TMP-SMX remarkably reduced vaginal colonization by E. coli during and up to 30 days after therapy. For the ofloxacin-treated women, eradication of vaginal E. coli was associated with a high ratio of drug concentration in vaginal fluid to that in serum. We conclude that ofloxacin and TMP both achieve high concentrations in vaginal fluid and are equally successful in eradicating E. coli from the vagina.

New antibiotics: carbapenems, monobactams and quinolones

New beta lactams and the quinolone class of antibiotics represent major improvements in the therapy of moderate to severe infections. These newer antibiotics have an extended spectrum of antimicrobial activity, excellent pharmacokinetic properties and low toxicity. The beta lactams include carbapenems, represented by imipenem-cilastatin, and monobactams, represented by aztreonam. Norfloxacin and ciprofloxacin are potent quinolones.

Serum and synovial fluid steady-state concentrations of trimethoprim and sulfadiazine in horses with experimentally induced infectious arthritis

The tarsocrural joints of 11 horses were inoculated with 1.2 to 2.16 x 10(6) viable Staphylococcus aureus organisms susceptible to a trimethoprim-sulfadiazine (TMP-SDZ) combination with minimal inhibitory concentration (MIC) of 0.25 micrograms of TMP/ml and 4.75 micrograms of SDZ/ml. Antimicrobial treatment consisted of oral administration of a TMP-SDZ combination--30 mg/kg of body weight given once daily (group-1 horses) or 60 mg/kg given as 30 mg/kg every 12 hours (group-2 horses). Paired serum and synovial fluid samples were obtained before intra-articular inoculation with the S aureus, after inoculation with S aureus but before antimicrobial treatment, and after inoculation at various hourly intervals after oral administration of the TMP-SDZ combination. The TMP-SDZ combination was administered daily in the 2 dosages for 21 days. Samples were collected after day 3 of repetitive drug administration so that drug steady-state concentration would have been achieved. Serum and synovial fluid samples were analyzed for TMP and SDZ concentrations. Administration of the TMP-SDZ combination at a dosage of 30 mg/kg once daily was not effective in maintaining TMP or SDZ concentrations above the MIC of TMP-SDZ for the S aureus (0.25 and 4.75 micrograms/ml for TMP and SDZ, respectively) in the infected synovial fluid or in maintaining adequate TMP concentration in the serum. The alternative use of the TMP-SDZ combination at a dosage of 60 mg/kg given as 30 mg/kg every 12 hours was effective in maintaining serum and synovial fluid concentrations of TMP and SDZ that were greater than the MIC for the infective organism.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma concentrations of sulfadoxine in healthy and malaria infected Thai subjects

The disposition of sulfadoxine was studied in the presence of pyrimethamine in 18 healthy Thai subjects who had been suffering from falciparum malaria in the 6 months prior to the study, and in 12 Thai patients with acute malaria. The volunteers were administered an oral dose of 500 mg sulfadoxine + 25 mg pyrimethamine (1 Fansidar tablet). They were classified retrospectively as responders (Group I, n = 8) or nonresponders (Group II, n = 10) according to previous response to treatment with Fansidar. The patients were treated with 3 Fansidar tablets corresponding to 1500 mg sulfadoxine and 75 mg pyrimethamine. Five of them were completely cured. Seven patients showed R I or R II resistance. In all cases blood samples were collected up to 288 h post dose. The resultant plasma was analyzed for active (i.e. unchanged) and total sulfadoxine using a modified Bratton-Marshall method. In the healthy volunteers the plasma concentration time course of total sulfadoxine was similar for responding and nonresponding subjects. However, in nonresponders active sulfadoxine tended to show shorter half-lives (harmonic means were 212 h vs 267 h, respectively). Furthermore, significantly higher amounts of metabolites (mainly N4-acetylsulfadoxine) were present in plasma of nonresponders. In contrast to these findings, in malaria patients, plasma concentrations of active and total sulfadoxine were even higher in nonresponders as compared to the subjects who could be successfully cured. Furthermore, in this case there was no increase of the amount of metabolites in plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

[Studies of the pharmacokinetics and bioavailability of a new trimethoprim/sulfamethoxazole preparation in healthy volunteers]

The objective of this study was to determine both the pharmacokinetic parameters and the bioavailability of a newly developed trimethoprim/sulfamethoxazole preparation (cotrimoxazole, Kepinol forte, 160 mg of trimethoprim/800 mg of sulfamethoxazole) in comparison with a reference preparation customary in trade and registered according to the AMG 1976, after single oral administration. For this purpose the test and the reference preparation were examined in a randomized 2-way crossover design (Latin square) in 12 volunteers each. Both dosage forms led to maximum plasma levels of approx. 1250 ng/ml of trimethoprim and about 40 micrograms/ml of sulfamethoxazole 1.5-2 h after application; the plasma half-lives were about 9 h for trimethoprim and around 8.5 h for sulfamethoxazole. The statistical comparison (ANOVA, confidence intervals according to Westlake, Pratt-Wilcoxon test) of the pharmacokinetic parameters found in the study resulted in bioequivalence of the newly developed trimethoprim/sulfamethoxazole preparation and the reference preparation. Furthermore, after the administration of both preparations no marked side effects worth mentioning were observed, suggesting a good and comparable clinical tolerability of the two preparations.

[Intraindividual comparison of the elimination kinetics of Lipofundin S and Intralipid in consecutive lipid tolerance tests]

Two intravenous fat tolerance tests (IVFTT) were performed in 16 healthy volunteers and 8 patients suffering from hypertriglyceridemia (HTG). We compared Lipofundin S (Braun, Melsungen) with Intralipid (Kabi Vitrum, Stockholm), using both 10- and 20% concentrations. Time intervals between the tests were 1 h for the volunteers and 2 h for the patients with HTG, respectively. Fractional elimination rates were obtained from light scattering intensity of serum samples. They were significantly higher for Lipofundin S (9.61%/min for healthy men and 12.48%/min for healthy women) compared to Intralipid (7.09%/min for healthy men and 9.41%/min for healthy women). This difference occurred independently of (1) serum triglyceride concentrations and sex of the volunteers, (2) concentrations of lipid emulsions (10 vs. 20%), and (3) the test sequence (Lipofundin S or Intralipid first). This means that the elimination kinetics during an IVFTT are not influenced by a foregoing test. Similar features of both emulsion types were: (1) Faster elimination in women compared to men, and in healthy volunteers compared to HTG patients; (2) inverse correlation between fractional elimination rates and serum triglyceride concentrations. Fractional elimination rates of Lipofundin S and Intralipid were closely interrelated. Obviously there exists an intra-individually characteristic elimination capacity for exogenous triglycerides.

UTIs and two new antibiotics in the elderly

Of the new antimicrobials available for the treatment of urinary tract infections (UTIs), aztreonam and imipenem/cilastatin represent two structurally unique, but distinct, classes of beta-lactam antibiotics. Aztreonam has a directed spectrum of activity covering gram-negative bacilli usually associated with UTIs. In comparative clinical trials of patients with complicated UTIs, aztreonam is well-tolerated and is as effective as conventional control regimens, including aminoglycosides. On the other hand, the antimicrobial spectrum of imipenem/cilastatin includes not only gram-negative bacilli but also gram-positive cocci and anaerobes. As such, this broad-spectrum antibiotic should be reserved for the treatment of mixed infections.