Showing papers by "Gideon Koren published in 1998"

Drugs in Pregnancy

Abstract: Before marketing a new drug, the manufacturer almost never tests the product in pregnant women to determine its effects on the fetus. Consequently, most drugs are not labeled for use during pregnancy. Typically, descriptions of drugs that appear in the Physicians' Desk Reference and similar sources contain statements such as, “Use in pregnancy is not recommended unless the potential benefits justify the potential risks to the fetus.” Since the risk has been adequately established for only a few drugs, physicians caring for pregnant women have very little information to help them decide whether the potential benefits to the mother outweigh . . .

Pregnancy outcome following maternal use of the new selective serotonin reuptake inhibitors : a prospective controlled multicenter study

Abstract: Context.—Although a large number of women of reproductive age use new selective serotonin reuptake inhibitors (SSRIs) and half of all pregnancies are unplanned, no data exist on the safety of these agents for the human fetus.Objective.—To assess fetal safety and risk of fluvoxamine, paroxetine, and sertraline.Design.—A prospective, multicenter, controlled cohort study.Setting.—Nine Teratology Information Service centers in the United States and Canada.Patients.—All women who were counseled during pregnancy following exposure to a new SSRI and followed up by the participating centers. Controls were randomly selected from women counseled after exposure to nonteratogenic agents.Main Outcome Measures.—Rates of major congenital malformations.Results.—A total of 267 women exposed to an SSRI and 267 controls were studied. Exposure to SSRIs was not associated with either increased risk for major malformations (9/222 live births [4.1%] vs 9/235 live births [3.8%] in the controls, relative risk, 1.06, 95% confidence interval, 0.43-2.62) or higher rates of miscarriage, stillbirth, or prematurity. Mean (SD) birth weights among SSRI users (3439 [505] g) were similar to the controls (3445 [610] g) as were the gestational ages (39.4 [1.7] weeks vs 39.4 [1.9] weeks).Conclusion.—The new SSRIs, fluvoxamine, paroxetine, and sertraline, do not appear to increase the teratogenic risk when used in their recommended doses.

Benzodiazepine use in pregnancy and major malformations or oral cleft: meta-analysis of cohort and case-control studies

Abstract: Objective: To determine if exposure to benzodiazepines during the first trimester of pregnancy increases risk of major malformations or cleft lip or palate. Design Meta-analysis. Setting: Studies from 1966 to present. Subjects: Studies were located with Medline, Embase, Reprotox, and from references of textbooks, reviews, and included articles. Included studies were original, concurrently controlled studies in any language. Interventions:Data extraction and quality assessment were done independently and in duplicate. Main outcome measures: Maternal exposure to benzodiazepines in at least the first trimester; incidence of major malformations or oral cleft alone, measured as odds ratios and 95% confidence intervals with a random effects model. Results:Of over 1400 studies reviewed, 74 were retrieved and 23 included. In the analysis of cohort studies fetal exposure to benzodiazepine was not associated with major malformations (odds ratio 0.90; 95% confidence interval 0.61 to 1.35) or oral cleft (1.19; 0.34 to 4.15). Analysis of case-control studies showed an association between exposure to benzodiazepines and development of major malformations (3.01; 1.32 to 6.84) or oral cleft alone (1.79; 1.13 to 2.82). Conclusions:Pooled data from cohort studies showed no association between fetal exposure to benzodiazepines and the risk of major malformations or oral cleft. On the basis of pooled data from case-control studies, however, there was a significant increased risk for major malformations or oral cleft alone. Until more research is reported, level 2 ultrasonography should be used to rule out visible forms of cleft lip.

A Systematic Review of Lidocaine-Prilocaine Cream (EMLA) in the Treatment of Acute Pain in Neonates

Abstract: Objective . Neonates routinely undergo painful cutaneous procedures as part of their medical treatment. Lidocaine-prilocaine 5% cream (EMLA) is a topical anesthetic that may be useful for diminishing the pain from these procedures. EMLA is routinely used in children and adults. There is substantial apprehension about its use in neonates because of concerns that it may cause methemoglobinemia. The objective of this review was to determine the efficacy and safety of EMLA as an analgesic for procedural pain treatment in neonates and provide evidence-based recommendations for clinical practice. Methods . Systematic review techniques were used. Studies were identified using manual and computer-aided searches (Medline, EMBASE, Reference Update, personal files, scientific meeting proceedings). Behavioral (eg, facial action, crying) and physiologic (eg, heart rate, oxygen saturation, blood pressure, respiratory rate) outcome data from prospective nonrandomized controlled studies and randomized controlled trials in full-term and preterm neonates were accepted for inclusion to establish efficacy of EMLA. The risk of methemoglobinemia (defined as methemoglobin concentration >5% and requiring medical intervention) was estimated from all prospective studies. Results . Eleven studies of the efficacy of EMLA were included in the analysis. Infant gestational age at the time of delivery ranged from 26 weeks to full-term. Two studies included data from both neonates and older infants. The following procedures were studied: circumcision (n = 3), heel lancing (n = 4), venipuncture (n = 1), venipuncture and arterial puncture (n = 1), lumbar puncture (n = 1), and percutaneous venous catheter placement (n = 1). Nine studies were randomized controlled trials. The total sample size for each study ranged from 13 to 110 neonates. The dose of EMLA used was 0.5 g to 2 g in 9 studies, and was not specified in the others. The duration of application ranged from 10 minutes to 3 hours. The three studies that investigated the efficacy of EMLA for decreasing the pain of circumcision used a randomized controlled trial design. All of them demonstrated significantly reduced crying time during the procedure in the infants in the EMLA group compared with the infants in the control group. Facial grimacing, assessed in two of the studies, was also significantly lower in the EMLA group. Using meta-analytic techniques, the heart rate outcome data for two studies was summarized. Increases in heart rate compared with baseline values were 12 to 27 beats per minute less for the EMLA group than in the placebo group during various stages of the surgical procedure. Three studies that investigated the pain from heel lancing were randomized controlled trials; the other was a nonrandomized controlled study. None demonstrated a significant benefit of EMLA for any of the outcome measures used to assess pain (ie, behavioral pain scores, infant crying, heart rate, blood pressure, respiratory rate, oxygenation parameters). One randomized controlled study of the pain from venipuncture showed that infants treated with EMLA had significantly lower heart rates and cry duration compared with infants treated with a placebo. In one nonrandomized study, a significantly lower behavioral pain score was observed for infants treated with EMLA compared with the control group. Infant heart rate, however, did not differ between the groups. In one randomized controlled study of pain from percutaneous venous catheter placement, EMLA resulted in a significantly lower increase in heart rate and respiratory rate. Behavioral pain scores were significantly lower during arterial puncture in one nonrandomized controlled study. EMLA did not reduce physiologic changes or behavioral pain scores in one randomized controlled trial in infants undergoing lumbar puncture. Meta-analytic techniques revealed that methemoglobin concentrations did not differ between EMLA-treated and placebo-treated infants (weighted mean difference, −0.11%; 95% confidence interval, −0.31% to 0.10%). The incidence of clinically important methemoglobinemia from all prospective studies was 0% (95% confidence interval, 0.0% to 0.2%). There was insufficient data to assess the risk with multiple doses of EMLA. Four studies measured concentrations of lidocaine in the plasma of neonates who had been treated with EMLA. In all cases, concentrations were Conclusions . EMLA diminishes pain during circumcision. It may also diminish the pain from venipuncture, arterial puncture, and percutaneous venous catheter placement; however, efficacy data for these procedures are limited. EMLA does not diminish the pain from heel lancing. Based on available data, EMLA is recommended for the treatment of pain from circumcision but not heel lance. There is insufficient data to recommend its use for other procedures. Single doses do not cause methemoglobinemia. Additional research is recommended in neonates before EMLA is used routinely for procedures other than circumcision and to determine the safety of repeated administration.

Long QT and ventricular arrhythmias in transgenic mice expressing the N terminus and first transmembrane segment of a voltage-gated potassium channel

Abstract: Voltage-gated potassium channels control cardiac repolarization, and mutations of K+ channel genes recently have been shown to cause arrhythmias and sudden death in families with the congenital long QT syndrome. The precise mechanism by which the mutations lead to QT prolongation and arrhythmias is uncertain, however. We have shown previously that an N-terminal fragment including the first transmembrane segment of the rat delayed rectifier K+ channel Kv1.1 (Kv1.1N206Tag) coassembles with other K+ channels of the Kv1 subfamily in vitro, inhibits the currents encoded by Kv1.5 in a dominant-negative manner when coexpressed in Xenopus oocytes, and traps Kv1.5 polypeptide in the endoplasmic reticulum of GH3 cells. Here we report that transgenic mice overexpressing Kv1.1N206Tag in the heart have a prolonged QT interval and ventricular tachycardia. Cardiac myocytes from these mice have action potential prolongation caused by a significant reduction in the density of a rapidly activating, slowly inactivating, 4-aminopyridine sensitive outward K+ current. These changes correlate with a marked decrease in the level of Kv1.5 polypeptide. Thus, overexpression of a truncated K+ channel in the heart alters native K+ channel expression and has profound effects on cardiac excitability.

Pregnancy outcome following maternal organic solvent exposure: A meta‐analysis of epidemiologic studies

Abstract: Background Evidence of fetal damage or demise from occupational organic solvent levels that are not toxic to the pregnant woman is inconsistent in the medical literature. The risk for major malformations and spontaneous abortion from maternal inhalation of organic solvent exposure during pregnancy was summarized using meta-analysis. Methods Medline, Toxline, and Dissertation Abstracts databases were searched to locate all research papers published in any language from 1966 to 1994. Included were studies that were case-control or cohort in design and indicated first trimester (or up to 20 weeks gestation for spontaneous abortion) maternal solvent exposure. A summary odds ratio (ORs) with 95% confidence intervals (CI) was calculated from research results combined by the Mantel-Haenszel method. Results In total, 559 studies were obtained from the literature search. Five studies for each outcome of interest qualified for inclusion in the analysis. The ORs for major malformations from five studies (n = 7,036 patients) was 1.64 (CI 1.16–2.30) and for spontaneous abortion from five studies (n = 2,899 patients) was 1.25 (CI 0.99–1.58). Conclusions Maternal occupational exposure to organic solvents is associated with a tendency toward an increased risk for spontaneous abortion and additional studies may affect the trend. There is a statistically significant association with major malformations which warrants further investigation. Am. J. Ind. Med. 34:288–292, 1998. © 1998 Wiley-Liss, Inc.

A prospective controlled multicentre study of clarithromycin in pregnancy

Abstract: Clarithromycin is a relatively new macrolide antibiotic with an action spectrum similar to that of erythromycin. Its main indications for use are for upper and lower respiratory and skin and soft tissue infections. Little is known about its safety in pregnancy, although animal reproductive studies found an increased rate of cardiovascular anomalies, cleft palate, and embryonic loss. Human data, limited to case reports and one small uncontrolled study, cannot allow evidence based counseling of pregnant women who were exposed to the drug before finding out they were pregnant. Pregnant women who had been counseled on the use of clarithromycin by five centers, were matched for age, smoking, and alcohol use with a control group of pregnant women who were exposed to nonteratogenic antibiotics. A total of 157 women were followed up. Of these, 122 were exposed to the drug in the first trimester. There were no significant differences found between the two groups in the rates of major and minor malformations; 2.3 versus 1.4% for major (p = 0.86) and 5.4 versus 4.9% for minor (p = 0.96). Spontaneous abortion rates in the exposed group was significantly different, higher (14%) than in the control group (7%) (p = 0.04). This first prospective controlled study of exposure to clarithromycin in pregnancy suggests that this agent does not increase the rate of major malformations above the baseline risk of 1-3%. The higher rate of reported spontaneous abortions, although still within the expected baseline rate, may warrant further study.

Pregnancy outcome following maternal use of the new selective serotonin reuptake inhibitors : a prospective controlled multicenter study

Abstract: Context.—Although a large number of women of reproductive age use new selective serotonin reuptake inhibitors (SSRIs) and half of all pregnancies are unplanned, no data exist on the safety of these agents for the human fetus.Objective.—To assess fetal safety and risk of fluvoxamine, paroxetine, and sertraline.Design.—A prospective, multicenter, controlled cohort study.Setting.—Nine Teratology Information Service centers in the United States and Canada.Patients.—All women who were counseled during pregnancy following exposure to a new SSRI and followed up by the participating centers. Controls were randomly selected from women counseled after exposure to nonteratogenic agents.Main Outcome Measures.—Rates of major congenital malformations.Results.—A total of 267 women exposed to an SSRI and 267 controls were studied. Exposure to SSRIs was not associated with either increased risk for major malformations (9/222 live births [4.1%] vs 9/235 live births [3.8%] in the controls, relative risk, 1.06, 95% confidence interval, 0.43-2.62) or higher rates of miscarriage, stillbirth, or prematurity. Mean (SD) birth weights among SSRI users (3439 [505] g) were similar to the controls (3445 [610] g) as were the gestational ages (39.4 [1.7] weeks vs 39.4 [1.9] weeks).Conclusion.—The new SSRIs, fluvoxamine, paroxetine, and sertraline, do not appear to increase the teratogenic risk when used in their recommended doses.

Pregnancy outcome following first trimester exposure to sumatriptan

Abstract: We prospectively compared pregnancy outcome after exposure to sumatriptan with that of disease-matched controls and nonteratogen controls. There were no differences in the rates of live births, spontaneous abortions, therapeutic abortions, or major birth defects among the three groups. This first prospective report suggests that the use of sumatriptan during organogenesis is not associated with an apparent increased risk of major birth defects.

Ifosfamide-induced Nephrotoxicity in Children: Critical Review of Predictive Risk Factors

Abstract: Ifosfamide is widely used in the treatment of pediatric solid tumors. Its main adverse effects are various forms of renal tubular and glomerular damage. Many risk factors have been proposed to play a role in the development and severity of nephrotoxicity in children receiving ifosfamide, among which are 1) patient's age, 2) cumulative ifosfamide dose, 3) concurrent administration of cis or carboplatinum, 4) unilateral nephrectomy, and 5) method of ifosfamide administration. However, presently there is no consensus regarding the weight of each one of them. Therefore, we critically reviewed the major studies that have evaluated the different risk factors in an attempt to determine the relative importance of each. Cumulative ifosfamide doses of ≥60 g/m[2][1] appears to be the most consistent independent predictor for both the development and the severity of nephrotoxicity, whereas a younger age (<5 years of age) was associated primarily with the more severe and chronic forms of proximal tubulopathy. Comparable incidence and severity forms of proximal tubulopathy among children who had been treated with cis platinum in addition to ifosfamide and those who had not indicate that platinums probably potentiate ifosfamide-induced renal damage rather than act as a major independent risk factor. Finally, although unilateral nephrectomy has been proposed as a significant risk factor in different studies, the relatively small number of nephrectomized children in these cohorts limit the strength of this association. To reduce the frequency and severity of ifosfamide-induced nephrotoxicity, it appears that cumulative doses of 60 g/m[2][1]should be considered carefully, especially in children <5 years of age. [1]: #ref-2

Electronic measurement of compliance with mercaptopurine in pediatric patients with acute lymphoblastic leukemia.

Abstract: Twenty-four pediatric patients with acute lymphoblastic leukemia (ALL) on maintenance therapy were evaluated for their compliance with taking their prescribed doses of oral mercaptopurine (6-MP). Procedure and Results. We utilized the Medication Event Monitoring System (MEMS; Aprex Corporation, Fremont, CA) for the study. Compliance was defined as the number of days doses were taken as a percentage of the total number of days doses were prescribed during the study period. The mean age of the patients was 7.3 years (range 2.6-17.2 (years). Patients were evaluated for a mean of 44 days (range 15-94 days). Thirty-three percent of patients (8) took less than 90% and 17% (4) took less than 80% of their prescribed pills. Eight patients were also evaluated for a difference in compliance between morning and evening administration. For the comparison of compliance between a morning vs. an evening schedule a trend toward improved compliance in the evening was found. Five patients had an increase and one patient a decrease in compliance with an evening schedule (differences ranged from 0.2% to 51.3%), with two patients having 100% compliance on both schedules. Conclusions. Our data raise concern that a significant proportion of pediatric patients are non-compliant with pill taking and demonstrate that the timing of administration of 6-MP in children with ALL may be crucial in some patients and supports the hypothesis that evening administration of 6-MP is associated with a lower risk of relapse.

Clinical pharmacology and therapeutic drug monitoring in neonates and children.

Abstract: From a pharmacotherapy perspective, the process of development and growth represents an unstable and dynamic condition. Age-related changes in drug absorption, distribution, and metabolism among neonates, infants, and prepubescent children create a unique situation that may increase drug toxicity of some agents and protect from toxicity of other agents. Understanding the age-related changes in drug disposition that are relevant for therapeutic response and toxicity is essential for optimizing pharmacotherapy at different stages of childhood.

Toxic digoxin-drug interactions: the major role of renal P-glycoprotein.

Abstract: The clinical use of digoxin is complicated by a large number of drug interactions leading to severe toxicity of the cardiac glycoside. The discovery that digoxin is actively secreted by the renal tubular cell via the p-glycoprotein drug efflux pump has led us to examine whether commonly interacting drugs do so by inhibiting renal tubular secretion of digoxin. We review digoxin-drug interactions which have been studied kinetically in humans, where there are sufficient data on renal clearance of digoxin and GFR.

A model for the prediction of digoxin-drug interactions at the renal tubular cell level.

Abstract: Digoxin-drug interactions are relatively common causes of digitalis toxicity. Recently, the clinical importance of the renal tubular secretion of digoxin has been proven by documenting drug interactions at this level. The authors describe a model using cultured renal tubular cell monolayers that can be used to predict drug interactions with the cardiac glycoside. This model accurately documents known clinical digoxin interactions such as those with verapamil and propafenone. The common feature of these interactions is that they involve P-glycoprotein substrates (e.g., digoxin, vincristine, vinblastine) or inhibitors (e.g., quinidine, cyclosporine). In the case of the newly described interaction of digoxin with itraconazole, the model preceded the emergence of clinical cases.

Long-Term Neurodevelopmental Risks in Children Exposed in Utero to Cocaine: The Toronto Adoption Studya

Abstract: Children exposed in utero to cocaine are at risk for long-term neurobehavioral damage not just because of the drug itself, but also because of clustering of other health determinants, including low socioeconomic status, low maternal education, and maternal addiction, to mention a few. One methodologic approach to separate the direct neurotoxic effects of cocaine from these synergistic insults is to follow up a cohort of children exposed in utero to cocaine and given up for adoption to middle-upper class families. The Toronto Adoption Study, supported by Health Canada, has proven the direct neurotoxic effects of cocaine on IQ and language. These effects are mild to moderate as compared to those measured in children exposed in utero to cocaine and reared by their natural mothers.

Valproic acid use in psychiatry: issues in treating women of reproductive age.

Abstract: Valproic acid, a well known anticonvulsant, is being used by psychiatrists increasingly to manage bipolar and other affective disorders. Because of the demographics of the population affected by such psychiatric conditions, more women of childbearing age are likely to be exposed to this teratogenic drug. Neural tube defects (NTD) are the most common of the major anomalies associated with in utero valproic acid exposure, and are estimated to occur in 1% to 2% of exposed fetuses. Other teratogenic effects include facial dysmorphism, congenital cardiac defects, limb reduction defects and other skeletal anomalies. Prenatal diagnosis, in particular maternal serum alpha-fetoprotein screening and targeted ultrasonography, should be offered to all pregnant women exposed to valproic acid and couples need to be aware of the prenatal diagnostic options available to them. Periconceptual prophylaxis with high doses of folic acid is recommended for all women on valproic acid and counselling should also emphasize planning pregnancy to optimize folic acid supplementation. Psychiatrists should be aware of the teratogenic potential of valproic acid and know how to counsel their patients of reproductive age.

A double-blind, randomized, placebo-controlled trial of eutectic lidocaine/prilocaine cream 5% (EMLA) for analgesia prior to cryotherapy of warts in children and adults

Abstract: Liquid nitrogen cryotherapy is an effective treatment modality for verrucae in children. However, sometimes the pain of the procedure is too much for the young child. In such instances the availability of an effective topical anesthetic would be of tremendous benefit. Warts are usually present on hardened skin, that is, the palms, periungual areas, and soles. In a double-blind, randomized, placebo-controlled, single-center, parallel-group trial with one visit, children (6-18 years old) and adults (>18 years old) had 2.5 g of lidocaine/prilocaine cream 5% applied under an occlusive dressing to the wart and a 1 to 2 mm area surrounding it 1 hour prior to liquid nitrogen cryotherapy. In both age groups the warts were subdivided by location-hardened skin areas versus nonhardened skin sites. The topical anesthetic was then removed and cryotherapy applied for 5 to 10 seconds. The pain of cryotherapy was assessed by the patient on a visual analogue scale (VAS) immediately after the cryotherapy and 4 and 8 hours later. There was no statistically significant difference in the pain of cryotherapy experienced following the application of active cream (n = 64) and placebo (n = 64). Exploratory subgroup analysis by wart location showed promising results for lidocaine/prilocaine cream 5% over placebo in children with warts on hardened skin sites (palms and soles). The topical anesthetic was safe and generally well-tolerated. Lidocaine/prilocaine cream 5% may provide some anesthesia in children receiving cryotherapy when the wart is on the palms or soles. Further studies are needed to better understand the site and age specificity of the anesthetic properties of lidocaine/prilocaine cream 5% when used to reduce the pain experienced during cryotherapy of warts.

Steady-state pharmacokinetics of isotretinoin and its 4-oxo metabolite : Implications for fetal safety

Abstract: Isotretinoin is the most potent human teratogen on the market. Women for whom contraception fails may conceive during or soon after discontinuing isotretinoin therapy, making its elimination kinetics a crucial determinant of fetal safety. The steady-state pharmacokinetics of isotretinoin and its major 4-oxo metabolite were studied in 16 adult patients treated for acne who were receiving doses that ranged from 0.47 to 1.7 mg/kg daily. This is the first study of the pharmacokinetics of isotretinoin in women of childbearing age (n = 11). The clinical efficacy and tolerability of isotretinoin was investigated, and the correlation between these data and steady-state serum concentrations of isotretinoin was tested. The concentration-time data best fitted a two-compartment open model with linear elimination. There was no correlation between efficacy and tolerability of isotretinoin and steady-state serum concentrations. There was no correlation between dose of isotretinoin and steady-state concentration, due to the large variability in apparent clearance. Values for elimination half-life (t1/2) of isotretinoin and its metabolite were 29+/-40 hours and 22+/-10 hours, respectively. These data suggest a longer elimination t1/2 of the parent drug than previously reported. This is probably due to the longer sampling time used in this study (as long as 28 days). This study suggests that a greater variability exists in the safe time after discontinuation of the drug for onset of conception.

Sequential use of intravenous and oral acyclovir in the therapy of varicella in immunocompromised children.

Abstract: Background Immunocompromised children are at risk for disseminated varicella infections. Standard management involves hospitalization and intravenous acyclovir for 7 to 10 days. This approach is expensive, is inconvenient and may not be necessary. We undertook a pilot study to assess the safety and efficacy of an alternative approach that utilized a combination of intravenous (i.v.) followed by oral (p.o) acyclovir in a cohort of immunocompromised children. Methods The cohort consisted of 26 immunocompromised children between the ages of 1.5 and 12.7 years (mean, 6.3). Therapy was commenced with i.v. acyclovir (1500 mg/m2/day in 3 divided doses). Concurrent management included holding or reducing immunosuppressive therapy (by 50%) and administering varicella-zoster immunoglobulin in 69% (11 of 16) of cases where exposure to chickenpox was recognized. Patients were eligible to switch to p.o therapy after receiving a minimum of 48 h of i.v. acyclovir therapy provided they were afebrile; had no new lesions for 24 h; had no internal organ involvement and were able to tolerate oral medications. Patients were observed in hospital for a further 24 h and then discharged provided they remained well. Oral acyclovir was continued for a total of 7 to 10 days (i.v. plus p.o). Results Of the 26 patients 25 were successfully switched from i.v. to p.o after 4.1 +/- 1.2 days (mean +/- SD) (range, 2.3 to 6) Children had fever for a mean of 2.0 +/- 1.6 days (range, 0 to 5) and developed new lesions for 2.9 +/- 0.7 days (range, 2 to 4). All 25 patients switched to p.o therapy had resolution of their disease and no patient required resumption of i.v. therapy. Conclusions The sequential use of i.v. followed by p.o acyclovir is feasible in the treatment of varicella in immunocompromised children and results in a reduction in duration of intravenous therapy and hospitalization.

Pharmacokinetic predisposition to nicotine from environmental tobacco smoke : A risk factor for pediatric asthma

Abstract: During the last decade several studies have shown that children whose parents smoke have higher rates of asthma. Recently, hair concentrations of cotinine have been shown to reflect systemic exposure to this constituent of smoke in both children and adults. At the present time it is not known, however, why some children exposed to passive smoking have asthma while others, similarly exposed, do not. The present study aimed at verifying whether asthmatic children are different from nonasthmatic children exposed to similar degrees of passive smoking in the way their bodies handle nicotine, a constituent of cigarette smoke. Seventy-eight asthmatic children were compared to 86 control children, all attending a consulting pediatric clinic in Toronto. A questionnaire completed by the parents and children detailed the daily number of cigarettes the child was exposed to and the identity of the smokers. Clinical data were extracted from the patients' charts. Urinary (corrected for creatinine) and hair concentrations of cotinine were measured by radioimmunoassays. The asthmatic and control children were of similar age, gender, and ethnic distribution, parental education, and socioeconomic status. Parents of asthmatic children tended to report a lower daily number of cigarettes (7.4 +/- 1.3/day vs. 11.2 +/- 2.3/day, p = 0.14), and this report agreed with the trend of urinary cotinine (47.1 +/- 9.1 ng/mg vs. 62.6 +/- 11.5 ng/mg, respectively). Conversely, children with asthma had on average twofold higher concentrations of cotinine in their hair (0.696 +/- 0.742 ng/mg) than control children (0.386 +/- 0.383) (p = 0.0001). In a similar manner, the hair:urine concentration ratio was significantly higher in children with asthma (0.028 +/- 0.002) than in their controls (0.18 +/- 0.003) (p = 0.0001). These results suggest that under exposure to similar amounts of nicotine, children with asthma have on average twofold higher systemic exposure to this constituent of cigarette smoke. These data suggest that out of all children passively exposed to environmental tobacco smoke, those who exhibit asthma have a higher systemic exposure to nicotine, possibly due to lower clearance rate. This is the first evidence of pharmacokinetic predisposition to environmental tobacco smoke as an etiological factor in pediatric asthma.

Carbamazepine Interference with an Immune Assay for Tricyclic Antidepressants in Plasma

Abstract: Background: Drug toxicological screening is commonly used as a diagnostic tool in patients with suspected toxic ingestion. False positive results due to cross-reactive compounds in drug assays may lead to misdiagnosis and mismanagement, especially when child abuse is suspected. Case Report: Two of our patients with history of ingestion of carbamazepine were tested positive on screening with the tricyclic antidepressant immunoassay. The immunoassay's known cross-reactivity for carbamazepine is reportedly as low as 0.3%. Plasma samples of our patients were initially considered positive for tricyclic antidepressants because the cross-reaction of carbamazepine gave tricyclic antidepressant concentrations as imipramine equivalent sufficiently above the assay cut-off point (20 ng/mL). Later, confirmatory urine testing of both patients using high-performance liquid chromatography was negative for tricyclic antidepressants. Conclusion: This interference has significant clinical implications, and can be av...

Assessment of the effect of the oral iron chelator deferiprone on asymptomatic Plasmodium falciparum parasitemia in humans.

Abstract: While the parenteral iron-chelating agent desferrioxamine B has anti-malarial activity in humans, the usefulness of an orally active chelator for this indication has not been investigated previously in vivo. We conducted a prospective, double-blind, placebo-controlled, cross-over trial of deferiprone (L1; CP20; 1,2-dimethyl-3-hydroxypyridin-4-one) in 25 adult Zambians with asymptomatic Plasmodium falciparum parasitemia. Deferiprone was administered daily for three or four days in divided doses of 75 or 100 mg/kg of body weight, dosages that are effective for treating iron overload. No reduction in asexual intra-erythrocytic parasites was observed during or after deferiprone treatment. The mean peak plasma concentration of deferiprone (108.9 +/- 24.9 micromol/L) achieved was within the range demonstrated to inhibit the growth of P. falciparum in vitro, but the systemic exposure as determined by the 24-hr plasma concentration-time curve would not be predicted inhibit growth in vivo. No evidence of deferiprone-associated hematological toxicity was noted in this short-term study of these subjects, all of whom had clinical evidence of normal body iron stores. Because of the risk of neutropenia and other adverse effects with higher doses or prolonged use of the chelator, additional trials of deferiprone as a sole anti-malarial agent would not seem to be justified. In contrast, further efforts are needed to develop other orally active iron-chelating agents specifically for their anti-malarial action.

Efficacy of Amlodipine in Pediatric Bone Marrow Transplant Patients

Abstract: The calcium antagonist amlodipine may have the potential for expanded use in children owing to its physiochemistry and pharmacokinetic profile that facilitates once-daily dosing in a liquid formulation. Its safety and efficacy have not been previously evaluated in children. A retrospective analysis of 15 pediatric bone marrow transplant patients who had amlodipine incorporated into their antihypertensive drug regimen reveals significantly lower blood pressure as compared with baseline therapy (123.5+/-2.1 mmHg and 117.2+/-2.2 mmHg, systolic blood pressure before and during amlodipine, P<0.05; 81.5+/-1.8 mmHg and 75.5+/-2.6 mmHg, diastolic blood pressure before and during amlodipine, P<0.05). Amlodipine provided improved blood pressure control in this cohort and may provide a valuable pharmacologic alternative for treatment of pediatric hypertension.

Tunneling and enhanced magnetoresistance in Nd2/3Sr1/3MnO3 thin films with microcracks

Abstract: We found that microcracks in thin Nd2/3Sr1/3MnO3 films create a series of intrinsic break junctions which are ideal for investigating tunneling phenomena in this system. A comparison of films with and without cracks, which have similar ferromagnetic Curie temperature (Tc) of 140–150 K, shows that the cracked film has a lower insulator to metal transition temperature TM (97 K vs 140 K), three orders of magnitude higher resistivity at TM, and two times larger magnetoresistance at 1 T near TM. At T>TM we observed that ln ραT−1/4 in the uncracked film while in the cracked film a ln ραT−1/2 dependence was found. This indicates that the conductivity in the first case is due to variable range hopping in three dimension, while in the second case it is dominated by thermally activated tunneling across the insulating barriers (the microcracks).

Intravenous and oral propafenone for treatment of tachycardia in infants and children: pharmacokinetics and clinical response.

Abstract: To elucidate contribution of an active metabolite to overall clinical responses to propafenone, steady-state disposition of propafenone and its active metabolite and the clinical responses to treatment were examined in pediatric patients receiving intravenous or oral propafenone. There were more than ten-fold interindividual differences in apparent clearance, resulting in a wide range of the steady-state trough plasma concentrations of propafenone. The active metabolite, 5-hydroxypropafenone, was detected in four of the six patients receiving oral propafenone; however, two neonates receiving oral propafenone and all eight receiving intravenous propafenone had no detectable levels of 5-hydroxypropafenone in plasma. In nine patients for whom electrocardiographic (ECG) data were available, the PQ interval was significantly increased, whereas the QRS duration and the QTc interval were not. There was no close relationship between plasma concentrations of propafenone or 5-hydroxypropafenone and ECG parameters. Lack of good correlation between serum concentrations and clinical response precludes using a serum-concentration targeting strategy with propafenone therapy.