Preferential elimination of pivalate with supplemental carnitine via formation of pivaloylcarnitine in man

1. To evaluate the effectiveness of carnitine administration in aiding the elimination of pivalate liberated from pivampicillin, studies were undertaken on seven paediatric patients treated for 7 days with combined pivampicillin and molar excess of carnitine. 2. A 22-fold increase occurred in urinary carnitine ester excretion on the last day of treatment (2967 +/- 604 versus 134 +/- 50 mumol/day, p < 0.05); the pivaloylcarnitine was identified with 13C-n.m.r. Only pivalate was detected in the urinary carnitine ester g.l.c. profile, the amount of this ester was equal to 92% of the daily pivalate intake. 3. The renal clearance rate of carnitine esters significantly exceeded that of creatinine indicating that the carnitine ester was eliminated by active transport. 4. The plasma concentration and urinary output of free carnitine were not changed significantly by the treatment, and the free and esterified carnitine concentrations in red cells remained unchanged indicating that carnitine deficiency was prevented.     

Clinical and bacteriological effects of cefetamet pivoxil against community-acquired respiratory tract infections. Part II

We investigated clinical and bacteriological effects of cefetamet pivoxil (CEMT-PI) in community-acquired respiratory tract infections and obtained the following findings. That method was approximately equal to that of investigation in 1994. 1. Of the 431 respiratory tract infection cases that were treated with CEMT-PI according to a same protocol at a total of 41 institutions in Tokyo, Kanagawa-ken, Saitama-ken and Chiba-ken from January to the beginning of March 1996. Outpatients accounted for 98.1% of the subjects. Regarding genders to patients, slightly more females (52.6%) than males were included. Diagnoses given to these patients included pharyngo-laryngitis (53.5%), tonsillitis (20.4%) and acute bronchitis (19.1%). 2. We investigated clinical efficacy rates (the ratio of those excellent + good) classified by diseases. The improvement rates of pharyngo-laryngitis, tonsillitis and acute bronchitis were more than 85.0%. Other cases were small in number. That of chronic bronchitis-acute increasing change for the worse was 66.7%, pneumonia was 50.0% and bronchiectasis infection was 16.7%. It was not studied that clinical efficacy rates among those who were treated with 1 CEMT-PI tablet twice and among those who were given 2 tablets twice were significant level. 3. For the bacteriological study, a written material describing the method of collecting specimens, storage and transport in detail was distributed to the above mentioned institutions. The isolation and identification of suspected causative bacteria, determination of minimum inhibitory concentrations (MICs) and investigation of beta-lactamase production were conducted all together at section of studies, Tokyo Clinical Research Center. Suspected causative bacteria were detected from 274 (63.6%) cases. They included 88 strains of Haemophilus influenzae, 47 strains of Streptococcus pneumoniae, 42 strains of Streptococcus pyogenes, 20 strains of Moraxella subgenus Branhamella catarrhalis and 17 strains of Klebsiella pneumoniae subsp. pneumoniae. Suspected causative bacteria classified by diseases were S. pyogenes (tonsillitis), S. pneumoniae (acute bronchitis and secondary infection of chronic respiratory infection) and H. influenzae (pharyngo-laryngitis), and the detection frequency of those was high. The clinical efficacies (the ratio of improvement) classified by suspected causative bacteria were 84.4% against organism that was indicating CEMT and were 69.2% against organism that was not indicating CEMT.     

Acquired carnitine abnormalities in critically ill children

In order to characterize the role of carnitine during metabolic stress, we prospectively determined carnitine profiles in plasma and urine on admission, days 2, 5, 10 and 15, among 28 critically ill children free of any known conditions associated with secondary carnitine deficiency. More than 25% of plasma and 50% of urinary carnitine measurements were abnormal; 96% (27/28) of patients displayed on at least one occasion an abnormal [< -2 SD or > +2 SD] carnitine value in plasma. Three children had extremely low [< 10 micromol/l] free carnitine (FC) levels in plasma. Plasma esterified and FC levels on admission were not related to the risk of mortality [PRISM score], to muscle lysis [CK values], and to the caloric intake. Levels of FC and esterified carnitine in plasma were unrelated to those measured in urine. Conclusion: Abnormal plasma and urine carnitine measurements are frequently found in critically ill children; the biological significance of these perturbations remains unclear. Caution must be exercised before concluding that an abnormal carnitine value is indicative of an underlying hereditary metabolic disorder in this population.     

Carnitine-acylcarnitine translocase deficiency with severe hypoglycemia and auriculo ventricular block. Translocase assay in permeabilized fibroblasts

Deficiency of the enzymes of mitochondrial fatty acid oxidation and related carnitine dependent steps have been shown to be one of the causes of the fasting-induced hypoketotic hypoglycemia. We describe here carnitine-acylcarnitine translocase deficiency in a neonate who died eight days after birth. The proband showed severe fasting-induced hypoketotic hypoglycemia, high plasma creatine kinase, heartbeat disorder, hypothermia, and hyperammonemia. The plasma-free carnitine on day three was only 3 microM, and 92% of the total carnitine (37 microM) was present as acylcarnitine. Treatments with intravenous glucose, carnitine, and medium-chain triglycerides had been tried without improvements. Measurements in fibroblasts confirmed deficient oxidation of palmitate and showed normal activities of the carnitine palmitoyltransferases I and II and of the three acyl-CoA dehydrogenases. A total deficiency of the carnitine-acyl-carnitine translocase was found in fibroblasts using the carnitine acetylation assay (1986. Biochem. J. 236:143-148). This assay has been further simplified by seeking conditions permitting application to permeabilized fibroblasts and lymphocytes.     

Pharmacokinetics and bioavailability of a sustained-release diltiazem formulation (Mono-Tildiem LP 300 MG) after repeated administration in healthy volunteers

The usual dosage regimen of diltiazem (Tildiem) is 60 mg 3-4 times a day. A sustained-release formulation has been developed (Mono-Tildiem LP 300 mg) in order to allow a single daily administration. Two repeated dosing studies were performed in healthy volunteers. The absolute bioavailability of sustained-release diltiazem LP 300 mg was investigated using concomitant i.v. administration of 13C-labelled drug: absolute bioavailability of the "once a day" formulation was 35%. The second study compared sustained-release diltiazem LP 300 mg with the standard formulation of diltiazem. The results showed that the diltiazem plasma concentrations obtained after the LP formulation remained stable between 2 and 14 h after administration and were compatible with a once a day administration. Relative bioavailability of sustained-release diltiazem LP 300 mg was 79.3% compared with diltiazem. Therefore, a unitary dose of sustained-release diltiazem LP 300 mg was chosen as the dose equivalent to the daily dose administered with the standard diltiazem formulation.     

Palmitoyl-CoA stimulates cellular uptake and plasma membrane binding of carnitine

Carnitine cellular uptake and plasma membrane binding was investigated in S49 lymphoma cells. Palmitoyl-CoA was found to increase membrane binding of carnitine from 506 +/- 48 to 8,690 +/- 235 pmol/mg membrane protein. Palmitate and CoA acted synergistically and increased carnitine binding to plasma membranes but could not replace palmitoyl-CoA. The effect of palmitoyl-CoA on membrane binding of carnitine was maximal at 10 microM and required the presence of ATP. Palmitoyl-CoA increased the cellular uptake rate of carnitine from 181 +/- 5 to 884 +/- 25 amol/cell and h-1. We conclude that palmitoyl-CoA is a major regulator of cellular uptake of carnitine and, based on quantitative estimations, that the carnitine carrier binds more than one carnitine molecule.     

Carnitine disposition before and during valproate therapy in patients with epilepsy

Free and total carnitine and acylcarnitine in plasma and urine samples was measured in 22 epileptic patients before and after 15 and 45 days of valproate (VPA) therapy and in 16 healthy volunteers on a single occasion. Carnitine plasma concentration and renal excretion observed in epileptic patients before VPA therapy did not differ from control values. After VPA was started, free and total plasma concentration decreased significantly (p < 0.05) from 49 +/- 17 to 35 +/- 16 at 15 days and to 35 +/- 13 nmol/ml at 45 days of therapy (free carnitine) and from 60 +/- 18 to 50 +/- 18 at 15 days and to 55 +/- 14 nmol/ml at 45 days of therapy (total carnitine), whereas acylcarnitine increased significantly (p < 0.05) from 10 +/- 8 to 14 +/- 8 at 15 days and to 18 +/- 16 nmol/ml at 45 days of therapy. Free carnitine urinary excretion decreased significantly (p < 0.05) from 200 +/- 135 to 115 +/- 76 and 118 +/- 75 mumol/24 h, whereas acylcarnitine urinary excretion increased significantly (p < 0.05) from 78 +/- 56 to 154 +/- 98 and 155 +/- 89 mumol/24 h after VPA therapy was started. As a consequence, acylcarnitine renal clearance increased significantly (+30%, p < 0.05) whereas free carnitine renal clearance did not change during VPA therapy. No difference was detected between 15 and 45 days of therapy. No patients experienced symptoms of VPA toxicity. Our results suggest that VPA in patients increases both formation and renal clearance of acylcarnitine.     

Concurrent occurrence of elevated ketone body and depressed carnitine level in underfed guinea-pigs

Food ingestion of male guinea-pigs was restricted to 10 g/day. Total carnitine content of liver of the underfed animals fell to 3.75 mumoles per liver (46.1% of control). Serum level of total carnitine was 35.0 nmoles/ml (64.4%) in the underfed animals while they developed high ketonemia, 384.2 nmoles/ml (555.2%). In "restricted' animals the carnitine levels also decreased in the muscles.     

Randomised controlled trial of L-carnitine as a nutritional supplement in preterm infants

AIMS: To evaluate the effect of L-carnitine supplementation (25 mg/kg/d) on the growth and incidence of hypoglycaemia in preterm infants. METHODS: A double blind, placebo controlled randomised trial, stratified for gestational age, was conducted of 86 preterm infants between 28 and 34 gestational weeks. The median gestational ages in the carnitine group and placebo groups were 30.7 weeks (range 28.0 to 33.6) and 31.4 weeks (range 28.0 to 33.9), respectively. The median birthweights were 1.557 kg (range 0.944 to 2.275) and 1.645 kg (range 0.885 to 2.545), respectively. RESULTS: Mean plasma free carnitine concentrations were below values for normal term infants in both groups on day 1 (carnitine group 44.8 mumol/l, placebo group 25.5 mumol/l) in the placebo group on day 7 (50.7 mumol/l), but in neither group on days 14 and 28. Total, free, and acylcarnitine concentrations were significantly increased in both urine and blood in the L-carnitine group. There was no significant difference between the placebo and carnitine supplemented groups in growth rate, as assessed by weight, length, skinfold thickness and head circumference measurements, or in the incidence of episodes of hypoglycaemia. CONCLUSION: The addition of carnitine as a nutritional supplement at a dose of 25 mg/kg/day did not improve growth in our group of preterm infants nor protect them from episodes of hypoglycaemia.     

Propranolol effect on plasma glucose, free fatty acid, insulin, and growth hormone in Graves' disease

A 3-hr glucose tolerance test was performed in 12 thyrotoxic patients before and after propranolol treatment for 30 days (120 mg/day). Plasma glucose, free fatty acid, insulin, and growth hormone levels were determined on each test and compared to each other and against nine clinically healthy volunteers. In eight thyrotoxic patients (subgroup A) an improvement in carbohydrate tolerance was observed after propranolol treatment, along with a fall in the previously elevated fasting FFA; no change in plasma insulin levels was observed. Plasma growth hormone levels were higher than normal both before and after propranolol; however, a 46% glucose-induced suppression was seen in both instances. In the other four patients (subgroup B) (who had had a marked and rapid weight loss) a deterioration of the previously normal glucosnificant changes in insulin levels. Elevated fasting plasma free fatty acids remained so despite propranolol treatment. Plasma growth hormone was higher than normal before and after propranolol; a late suppression (at 120 min) and no suppression at all were seen, respectively. After propranolol treatment, subgroup B had higher plasma free fatty acid than subgroup A in the fasting state and at 30 and 180 min. It is proposed that the improvement or deterioration in carbohydrate tolerance after propranolol treatment might be related to whether or not a satisfactory propranolol-induced lipolytic blockade is achieved, leading to a decrease in plasma free fatty acid levels, improved insulin sensitivity, and better peripheral glucose utilization. Therefore, a uniform dose of propranolol will not always be sufficient to obtain adequate lipolytic blockade, particularly if the thyrotoxic patient has had a marked and rapid weight loss.     

Quantification of carnitine, acetylcarnitine, and total carnitine in tissues by high-performance liquid chromatography: the effect of exercise on carnitine homeostasis in man

A method for the quantitative determination of carnitine, acetylcarnitine, and total carnitine in tissue was developed for application to clinical research and diagnosis. Human skeletal muscle and heart specimens (10-20 mg) were homogenized in 1 ml of water. Aliquots of the resulting homogenates (50 microliters) were extracted with 1.0 ml of acetonitrile:methanol (3:1) and the carnitine-related compounds were isolated using columns containing 300 mg of silica gel. Samples were then derivatized with 4'-bromophenacyl trifluoromethanesulfonate for spectrophotometric detection or 2-(2,3-naphthalimino)ethyl trifluoromethanesulfonate for fluorescence detection and quantified by high-performance liquid chromatography. Fluorometric detection of 2-(2,3-naphthalimino)ethyl ester derivatives afforded a 500-fold increase in sensitivity when compared to derivatization with 4'-bromophenacyl trifluoromethanesulfonate. This methodology permitted detection of acetylcarnitine in dilute human muscle homogenates at quantities of 790 fmol of acetylcarnitine injected. The method was applied to a series of human skeletal muscle biopsy samples obtained from subjects performing exercise at high work loads. The method permitted quantification of carnitine, acetylcarnitine, and total carnitine (sum of carnitine and all acylcarnitines) and demonstrated the specific redistribution of the carnitine pool from carnitine to acetylcarnitine with exercise above the lactate threshold. This HPLC method is facile, and provides a sensitive and specific approach for use in human biopsy specimens.     

Opportunities for promoting palliative medicine in cancer research

OBJECTIVE: To study the effect of cisplatin on plasma concentrations and urinary excretion of carnitine in ten patients with different malignancies treated with chemotherapy. METHODS: Carnitine concentrations were determined using a radioenzymatic assay and other metabolites by routine methods of clinical chemistry. Renal clearances were calculated by dividing urinary excretions by the respective plasma concentrations. RESULTS: Before treatment, all patients had a normal plasma carnitine concentration. During treatment with cisplatin, the plasma total carnitine concentration increased by approximately 30% and normalized 7 days after stopping therapy. Urinary excretion of total carnitine increased by a factor of 10 during cisplatin administration and also normalized 7 days after cessation of chemotherapy. This increase was due to excretion of both free carnitine and acylcarnitine and averaged approximately 1 mmol carnitine per day. Similarly, urinary clearance of total carnitine was increased during therapy with cisplatin by a factor of approximately 8 and returned to normal 7 days after chemotherapy. In comparison, patients with similar malignancies treated with radiotherapy showed no significant increase in renal carnitine excretion. Similar to urinary excretion of carnitine, excretion of glucose and phosphate, two metabolites also reabsorbed by the proximal tubule of the nephron, was increased during therapy with cisplatin. There was a strong linear correlation between urinary excretion of free carnitine and acylcarnitines. CONCLUSIONS: Treatment with cisplatin is associated with a tenfold increase in renal carnitine excretion, most likely due to inhibition of carnitine reabsorption by the proximal tubule of the nephron. Well-nourished patients support this loss of carnitine even after repeated cycles of chemotherapy without developing hypocarnitinaemia. However, cachectic patients with decreased dietary carnitine uptake may develop carnitine deficiency when treated repeatedly with chemotherapies including cisplatin.     

Bioavailability of morphine after administration of a new bioadhesive buccal tablet

A new bioadhesive buccal morphine tablet was developed for controlled release delivery of drug and improved bioavailability compared with oral controlled release tablet. In order to characterize the pharmacokinetic properties of this bioadhesive buccal formulation, a bioavailability study was performed in 12 healthy volunteers who received: a 30 mg oral controlled release tablet (A); a 20 mg aqueous solution retained in the mouth for 10 min (B); and the 60 mg bioadhesive buccal tablet placed between the lower gum and lip for 6 h (C). The mean amount of morphine absorbed from the solution was very low, only 2 mg of the 20 mg dose. After administration of forms A and C, plasma levels exhibit typical sustained release concentration-time curves. The mean amount of drug recovered from the residual bioadhesive buccal tablet after 6 h indicated that approximately 50% of the dose was released from the bioadhesive buccal tablet. The relative bioavailability of the buccal tablet (corrected for residual unabsorbed dose) compared with the controlled-release tablet was 98% based on the morphine AUC values. Good correlations between the AUC and the Cmax of the bioadhesive tablet for the drug and metabolite plotted versus the amount of morphine absorbed were found.     

Action of pentamidine-bound nanoparticles against Leishmania on an in vivo model

The efficiency of antileishmanial agents may be enhanced by improving their bioavailability with a colloidal drug carrier. We have investigated the action of free pentamidine, compared with pentamidine bound to polymethacrylate nanoparticles, in a rodent model. BALB/c mice were infected, via the tail vein, with 4 x 10(7) L. major (MON 74) promastigotes. Twelve days after infection, seven groups of mice were treated respectively with methylglucamine antimoniate (Glucantime) 5.56 mg/kg i.p. x 5 d., pentamidine bound nanoparticles (100 microM), unloaded polymethacrylate nanoparticles, unloaded nanoparticles associated with free pentamidine (100 microM) 0.1 ml i.v. x 3 d and free pentamidine isethionate (2.28 mg/kg and 0.17 mg/kg i.v. x 3 d.). Twenty-one days post infection, the mice were sacrificed and the Leishmania load in the liver calculated from the number of amastigotes/500 liver cells and total liver weight in treated and untreated mice. Results demonstrated a 77% amastigote reduction in the group treated with targeted pentamidine relative to the control group. The ratio free pentamidine/bound-pentamidine was approx. 12.     

Evaluation of the effect of long term valproic acid treatment on plasma levels of carnitine, ammonia and amino acids related to the urea cycle in pediatric epileptic patients

INTRODUCTION: Valproic acid (VPA) is an antiepileptic drug widely used in paediatrics. In spite of being a safe and effective anticonvulsant, VPA has been involved in the onset of changes in the metabolism of ammonia and carnitine, although few prospective studies have been made of this. OBJECTIVES: To evaluate the effect of long-term VPA administration, particularly on the metabolism of carnitine, ammonia and plasma amino-acids and the possible clinical repercussions of this in a group of epileptic patients studied prospectively and retrospectively. MATERIAL AND METHODS: A study was made of 102 epileptic children on long term anticonvulsant treatment mainly with VPA. These patients were divided into two groups: group I (n = 25) were studied prospectively (basal sample, after one, six and twelve months of treatment) and group II (n = 77) or long term treatment group (a single sample extraction). In each epileptic patient and in 56 children from a control group (group III) studies were made of free plasma carnitine, ammonia and amino-acids related to the urea cycle and the plasma levels of each anticonvulsant drug. RESULTS: It was observed that in group I there was a fall in plasma carnitine concentrations with time and a progressive rise which was statistically significant (p = 0.001) in plasma levels, mainly of ammonia, glutamine, glycine and ornithine, from the basal levels to those after a year of treatment in practically 100% of the children studied. In group II children on antiepileptic drugs, mainly VPA, were seen to have lower plasma carnitine levels than those in the control group and higher serum ammonia, glutamine and glycine levels than the healthy population not treated with anticonvulsants. These differences were statistically significant (p = 0.001). No relationship was found between the parameters studied and the plasma levels of the drug, type of epilepsy or presence of side effects. CONCLUSIONS: These changes show the negative effects of VPA on the metabolism of carnitine and ammonia. It would therefore seem advisable to monitor these parameters in epileptic children on long term antiepileptic treatment.     

The effect of prolonged lithium administration on the cAMP level in the rat striatum

Postmenopausal women were randomly given either oral calcium (500 mg/day, control group, n = 12) or a combination of estradiol valerate (EV, 2 mg/day for 21 days) with cyproterone acetate (CPA, 1 mg/day in the last 10 days of the treatment cycle, n = 19). EV+CPA reduced (P < 0.01) postmenopausal complaints, inducing regular withdrawal bleeds, with no hysteroscopic or hystologic evidence of endometrial hyperstimulation after 12 months of treatment. In the control group, spine bone mineral density (BMD) and the total body bone mineral (TBBM) decreased (P < 0.01), whereas urinary hydroxyproline excretion (OH-P/Cr), plasma bone Gla Protein (BGP) and lipid profile did not show any significant modification throughout the study. In the EV+CPA group, urinary OHP/Cr and plasma BGP levels decreased (P < 0.01) after 6 and 12 months, whereas both BMD and TBBM showed a small but significant (P < 0.01) increase. In this group, LDL cholesterol significantly (P < 0.01) decreased and HDL levels significantly (P < 0.01) increased after 6 and 12 months. In conclusion, the EV+CPA combination is effective in relieving menopausal symptoms, produces a good cycle control and a favourable lipid profile, preventing postmenopausal bone resorption.     

Elevated fasting total plasma homocysteine levels and cardiovascular disease outcomes in maintenance dialysis patients. A prospective study

The pharmacokinetics of itraconazole formulated in a hydroxypropyl-beta-cyclodextrin oral solution was determined for two groups of human immunodeficiency virus (HIV)-infected adults with oral candidiasis (group A, 12 patients with CD4+ T-cell count of >200/mm3 and no AIDS, and group B, 11 patients with CD4+ T-cell count of <100/mm3 and AIDS). Patients received 100 mg of itraconazole every 12 h for 14 days. Concentrations of itraconazole and hydroxyitraconazole, the main active metabolite, were measured in plasma and saliva by high-performance liquid chromatography. Pharmacokinetic parameters determined at days 1 and 14 (the area under the concentration-time curve from 0 to 10 h, the maximum concentration of drug in plasma [Cmax], and the time to Cmax) were comparable in both groups. Trough levels in plasma (Cmin) were similar in both groups for the complete duration of the study. An effective concentration of itraconazole in plasma (>250 ng/ml) was reached at day 4. At day 14, Cmin values of itraconazole were 643 +/- 304 and 592 +/- 401 ng/ml for groups A and B, respectively, and Cmin values of hydroxyitraconazole were 1,411 +/- 594 and 1,389 +/- 804 ng/ml for groups A and B, respectively. In saliva, only unchanged itraconazole was detected, and mean concentrations were still high (>250 ng/ml) 4 h after the intake, which may contribute to the fast clinical response. In conclusion, the oral solution of itraconazole generates effective levels in plasma and saliva in HIV-infected patients; its relative bioavailability is not modified by the stage of HIV infection.     

On carnitine requirements in full term and low birth weight neonates

The concentration of total carnitine in the blood serum of 15 newborns between days 5-21 of life was determined. The concentration of carnitine in low-birth-weight newborns is decreased in comparison with normal weight newborns; this deficiency may increase as a consequence of lack of carnitine provided with food or concomitant infection. The authors suggest that supplementation with carnitine be provided to this group of patients so as to prevent possible metabolic and clinical consequences.     

Plasma and tissue levels of lipids, fatty acids and plasma carnitine in neonates receiving a new fat emulsion

This study was undertaken to compare Intralipid with a new fat emulsion containing gamma-linolenic acid and carnitine, named Pediatric Fat Emulsion 4501, in neonates with regard to lipid and carnitine metabolism over a short period of total parenteral nutrition. There were 10 neonates in each group and they tolerated the total parenteral nutrition well. In spite of the gamma-linolenic acid supplementation in the new emulsion, arachidonic acid decreased significantly in plasma lipid esters and adipose tissue in both groups after 5 d of treatment. Also, there was a decrease in plasma docosahexaenoic acid which was more pronounced in the treatment group. The relative percentage values of linoleic and linolenic acids in adipose tissue were increased, indicating that newborns have a rapid accretion of fatty acids. Plasma-triglycerides were effectively cleared during the periods without fat infusion. In the group that received Pediatric Fat Emulsion 4501 the means of both free and total plasma carnitine concentrations increased significantly, whereas they tended to decrease in the Intralipid group.