Julia Klein

Comparison of oral iron chelator L1 and desferrioxamine in iron-loaded patients

The efficacy of the oral iron chelator 1,2-dimethyl-3-hydroxypyrid-4-one (L1) was compared with that of subcutaneous desferrioxamine in 26 patients with transfusional iron overload. Immediately after red-cell transfusion, 20 patients were randomised to receive either desferrioxamine (50 mg/kg daily as a 12 h subcutaneous infusion), or L1 (50 mg/kg daily by mouth). Patients were evaluated during treatment with the other drug after transfusion the next month. Mean (SD) daily urinary iron excretion was lower during L1 than during desferrioxamine (12.3 [6.7] vs 18.2 [15.3] mg/day). In 5 patients the dose of L1 was raised from 50 to 75 mg/kg daily; mean urinary iron excretion rose from 13.8 (7.0) mg/day to 26.7 (17.8) mg/day, comparable with that during desferrioxamine (24.9 [24.3] mg/day). Faecal iron excretion rose slightly over baseline in 6 patients studied during L1 administration (from 8.5 [0.9] mg/day to 12.2 [0.9] mg/day). Pharmacokinetic studies showed an elimination half-life for L1 of 117-237 min. Studies in dogs and in volunteers showed no absorption of the L1-iron complex, excluding a contribution of absorption of intraluminal complexes of L1 and food iron to urinary iron excretion. Further animal toxicity testing is needed before L1 can be studied in a broader group of patients.

A novel method using hair for determining hormonal levels in wildlife

ormones influence behaviour, and are also influ-enced by behaviour. Monitoring their levels cantherefore provide insights into the mechanistic aspects ofbehaviour. In male mammals for example, elevated levelsof testosterone are associated with increased aggressionand dominance (Creel et al. 1993, 1997; Mazur & Booth1998) and in social mammals, levels of stress hormones(e.g. corticosterone, glucocorticoid and cortisol) areassociated with rank (Sapolsky 1985; Creel et al. 1996,1997). Research has associated hormone levels with dif-ferent behaviours such as sexual, reproductive, courtship,parental, aggressive and feeding behaviours. Comparativetools for hormonal analysis provide insights into evolu-tionary theories based on behavioural aspects, such asreproductive suppression and the ‘challenge hypothesis’(e.g. Creel et al. 1993).In field studies, hormones are usually extracted fromblood samples, or noninvasively from saliva, urine andfaeces (Creel et al. 1992; Cavigelli 1999; Hirschenhauseret al. 1999; von Engelhardt et al. 2000). Samples derivedfrom trapped or handled animals are problematicalbecause stress may alter blood and urine hormonal levels(Creel et al. 1992). Additional problems with bloodsamples are that they are not always available, theamount that can be taken at a given time is limited, andvarious safety and ethical issues exist. Furthermore, bloodand saliva must be transported cold or frozen, conditionsthat are sometimes difficult to obtain in the field (Yang etal. 1998). Urine and faeces samples are sometimes diffi-cult to obtain from free-ranging animals that cannot becontinuously observed, or from species that deposit incommon latrines.An alternative source for hormones may be found inhair, which can be collected noninvasively, and is alreadyused to extract DNA (Woodruff 1993; Morin et al. 1994),trace metals, naturally occurring compounds and drugs(Wheeler et al. 1998). Hair is safe, readily available, andeasy to store and transport. Hair sampling does notinvolve pain or possible infection, and the analysis isunaffected by the momentary stress of capture (Yang et al.1998). Hair analysis may allow one to monitor hormonalchanges over weeks or months (between moults; Maurelet al. 1986) by shaving off a patch of hair and resamplingthe newly grown hair. Hormonal hair analysis offersonly a long-term profile, however, and is not suitable formonitoring hourly or daily (short-term) fluctuations inhormonal levels. It provides the resolution needed forstudies of main behavioural trends, especially in stablehierarchical social systems. Hair has already been used todiagnose early pregnancy in cows by detection of proges-terone (Liu et al. 1988), to detect oestradiol and testoster-one in cattle (Gleixner & Meyer 1997) and anabolicsteroid and corticosteroid abuse in athletes (Bowers S Hold et al. 1999; Kintz et al. 1999; Cirimeleet al. 2000). In humans, the levels of steroid hormones inhair do not vary significantly between different regions ofthe scalp (Wheeler et al. 1998). Oestradiol, progesteroneand testosterone levels measured in healthy humanadults’ hair correlate significantly with the levelsmeasured in their serum (Yang et al. 1998).As an example of the utility of this method, we usedata from our long-term study on rock hyrax,

Population baseline of meconium fatty acid ethyl esters among infants of nondrinking women in Jerusalem and Toronto.

The detection of fatty acid ethyl esters (FAEE) in meconium may provide an objective estimate of prenatal alcohol exposure independent of maternal history. The authors report the results of the first population-based study conducted to investigate basal FAEE levels in the meconium of neonates not exposed to alcohol. Two hundred seven nondrinking women and their neonates were recruited from Toronto and Jerusalem. FAEE were extracted from meconium by solid-phase extraction and analyzed by GC/FID. Similar procedures were conducted in six neonates born to confirmed heavy drinkers. Low levels of meconium FAEE were detected from both cohorts (mean, 1.37 nmol/g vs. 2.08 nmol/g, Toronto vs. Jerusalem). Ethyl stearate, oleate, and linoleate were below the limit of detection in >80% of all samples, whereas ethyl laurate and palmitate were detected in >50% of the samples. Ethyl myristate was the FAEE most commonly detected (>80%). All six meconium samples with confirmed maternal drinking histories tested positive for FAEE at significantly higher levels (mean, 11.08 nmol/g). The use of 2 nmol total FAEE/g meconium as the positive cutoff, when lauric and myristic acid ethyl esters were excluded, yielded the greatest sensitivity (100%) and specificity (98.4%). The authors conclude that certain FAEE are present at measurable levels in the meconium of neonates not exposed to maternal drinking, and correction is needed to allow high specificity.

A randomized, double-blind comparison of lumbar epidural and intravenous fentanyl infusions for postthoracotomy pain relief. Analgesic, pharmacokinetic, and respiratory effects.

Although epidural opioids frequently are used to provide postoperative analgesia, several articles have suggested that the analgesia after epidural fentanyl is similar to that after an equal dose of fentanyl given intravenously. To address this issue further, 29 postthoracotomy patients were studied in a randomized, double-blinded trial comparing a lumbar epidural fentanyl infusion with an intravenous fentanyl infusion for analgesia, plasma fentanyl pharmacokinetics, and respiratory effects for 20 h postoperatively. In all patients in both groups, good analgesia was achieved (pain score less than 3, maximum 10) over a similar time course, although the patients receiving epidural infusion required a significantly larger fentanyl infusion dose than did the patients receiving intravenous infusion (group receiving epidural fentanyl infusion: 1.95 +/- 0.45 micrograms.kg-1.h-1; group receiving intravenous fentanyl infusion: 1.56 +/- 0.36 micrograms.kg-1.h-1; P = 0.0002). The time course for the plasma fentanyl concentrations was similar in the two groups, and plasma fentanyl concentrations were not significantly different at any sampling period (T7-T20; group receiving epidural fentanyl infusion: 1.8 +/- 0.5 ng/ml; group receiving intravenous fentanyl infusion: 1.6 +/- 0.6 ng/ml; P = 0.06). Similarly, calculated clearance values for the two groups were not significantly different (group receiving epidural fentanyl infusion: 0.95 +/- 0.26 l.kg-1.h-1; group receiving intravenous fentanyl infusion: 0.87 +/- 0.25 l.kg-1.h-1; P = 0.3). Both groups demonstrated a similar degree of mild to moderate respiratory depression postoperatively, which was assessed with continuous respiratory inductance plethysmography and sequential arterial blood gas analysis. Side effects (nausea, vomiting, pruritus) were mild and did not differ between groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Systemic Exposure to Mercaptopurine as a Prognostic Factor in Acute Lymphocytic Leukemia in Children

BACKGROUND Despite a success rate of more than 90 percent in inducing remission in children with acute lymphocytic leukemia, 30 to 40 percent of such children relapse. Maintenance therapy during remission usually includes oral mercaptopurine and methotrexate. Recently, wide variability in the bioavailability of oral mercaptopurine has been demonstrated, and there is concern that this may affect the risk of relapse. METHODS To investigate whether lower systemic exposure to mercaptopurine may increase the risk of relapse in acute lymphocytic leukemia, we prospectively studied 23 children receiving maintenance therapy. On the basis of disease features, 11 were classified as being at low risk of relapse, and 12 at standard risk. Those who relapsed (n = 10) did not differ from those who did not in their mean age, hemoglobin level, mean daily dose of mercaptopurine and weekly dose of methotrexate, or the total number of days during which mercaptopurine and methotrexate therapy was interrupted. RESULTS There was a significant difference in the mean (+/- SEM) area under the mercaptopurine concentration-time curve achieved by a dose of 1 mg of mercaptopurine per square meter of body-surface area: 1636 +/- 197 nmol per liter x minutes in those who relapsed, as compared with 2424 +/- 177 nmol per liter x minutes in those who did not (P less than 0.005). This caused a significantly lower total daily systemic exposure to mercaptopurine in those who relapsed (104,043 +/- 12,812 nmol per liter x minutes) than in those who did not (168,862 +/- 18,830 nmol per liter x minutes) (P less than 0.005). An identical tendency prevailed when patients at low risk and patients at standard risk were analyzed separately. Kaplan-Meier analysis revealed that children in whom an area under the curve of less than 1971 nmol per liter x minutes was achieved by a dose of 1 mg of mercaptopurine per square meter had a significantly poorer prognosis than those with larger areas under the curve (P less than 0.01). Similarly, those with a total daily systemic exposure of more than 137,970 nmol per liter x minutes had a significantly better prognosis than those with a lower exposure (P less than 0.005). CONCLUSIONS Low systemic exposure to oral mercaptopurine during maintenance therapy for acute lymphocytic leukemia in childhood adversely affects prognosis. Children should be studied at the beginning of maintenance therapy to establish the pharmacokinetics of mercaptopurine, and the dose should be tailored to achieve an appropriate systemic exposure.

Hair Analysis of Cocaine: Differentiation Between Systemic Exposure and External Contamination

Cocaine has been shown to accumulate in hair of admitted users. Before using this test to verify cocaine use, however, it is crucial to differentiate between systemic exposure and external contamination from being in contact with crack smoke. In the present studies, the authors document that pyrolysis of crack results in hair accumulation of cocaine, but not its benzoylecgonine metabolite, whereas after admitted cocaine use both species are detectable in hair. External contamination with crack smoke is washable, whereas systemic exposure is not. The authors suggest these two criteria to distinguish systemic exposure from external contamination.

Critical comparison of novel and existing methods of compliance assessment during a clinical trial of an oral iron chelator.

The assessment of compliance is critical in the evaluation of the effectiveness of a new therapeutic agent. Fifteen patients with transfusion‐dependent β‐thalassemia, many of whom had previously demonstrated erratic compliance with deferoxamine, were enrolled in a clinical trial of a new oral iron chelator, 1,2‐dimethyl‐3‐hydroxypyrid‐4‐one (L1). Their compliance with this medication was estimated by several existing methods and the novel Medication Event Monitoring System (MEMS). Overall compliance as assessed by the MEMS was 78.5 ± 13.0% of prescribed doses taken, significantly lower than the corresponding rates calculated by pill counts and diaries (91.5 ± 9.2% and 94.1 ± 4.3%, respectively). However, several serious problems were encountered with the MEMS, mostly in the form of incorrect use of the device by the patients. Disclosure of the nature of the MEMS and the compliance monitoring process did not alter the rate of adherence with L1 therapy. Compliance as determined by pill counts did not differ between the 1st and 2nd 6‐month periods. Although not reaching statistical significance, a trend towards better L1 compliance occurred in those patients in whom serum ferritin levels decreased. Patients who filled at least 50% of their diaries had significantly better compliance by pill counts than those who completed less than 50% of their diaries (95.9 ± 4.1% and 86.5 ± 11.1%, respectively). Steady‐state L1 trough concentrations and 24‐hour urinary iron excretion did not correlate with L1 compliance. Given the limitations of the available techniques for monitoring compliance, including the new MEMS device, a combination of methods should be used in the evaluation of medication compliance during the investigation of a new drug.

Fentanyl pharmacokinetics and hemodynamic effects in preterm infants during ligation of patent ductus arteriosus.

A bolus of 30 μg·kg−1 fentanyl was given to nine preterm infants (gestational age 31.8 ± 4.7 weeks, weight 1100 ± 309 g) for induction of anesthesia for ligation of a patent ductus arteriosus. Thirty minutes after the injection, fentanyl plasma concentrations were between 7.7 and 13.6 ng·ml−1. Elimination half-life was 6–32 In (mean ± SD, 17.7 ± 9.3). Systolic blood pressure remained stable throughout surgery. There was a gradual increase in heart rate from 159 ± 12 min−1 at the time of skin incision to 173 ± 15 min−1 at the time of skin closure (P < 0.05). Fentanyl plasma concentrations remained virtually unchanged between 30 min (10.6 ± 1.9 ng·ml−1) and 120 min (9.6 ± 1.6 ng·ml1): whereas at the end of surgery most infants moved and breathed spontaneously. This phenomenon can be explained by redistribution of fentanyl from brain into pharmacodynamically inert tissues.

Fatty acid ethyl esters: a novel biologic marker for heavy in utero ethanol exposure: a case report.

The authors report testing the meconium of a newborn for the presence of FAEE. Meconium from a newborn of a woman who acknowledged drinking beer throughout pregnancy was tested. The authors also tested the meconiums of 3 newborns whose mothers did not drink at all while pregnant. The FAEE were extracted from the meconium samples using solid phase extraction (SPE), and were identified and quantitated by gas chromatography with flame ionization detection (FID). For assignment of retention times and determination of individual concentrations, authentic mixtures of FAEE were injected. The total FAEE concentration in the meconium of the alcohol-exposed infant was 13126 ng/g compared to a mean of 410 ng/g in the control meconiums. Also, in this case, palmitic, linoleic, and stearic ethyl esters were found in the alcohol-exposed infants meconium while they were not found in the unexposed infants meconium. In a parallel experiment, the authors spiked increasing amounts of ethyl alcohol (0-40mM) into the meconium from a newborn that was not exposed to ethanol in utero. The spiked samples were incubated for 4 hours at 37 degrees C and subsequently assayed for the presence of ethyl linoleate. In these experiments, they document for the first time that FAEE is produced in meconium. If confirmed by large studies, FAEE may become the first neonatal biologic marker for babies at risk for alcohol-related birth defects.

Clinical applications of hair testing for drugs of abuse--the Canadian experience.

During the last 2 decades there has been a substantial increase in illicit drug consumption in North America. It has been repeatedly shown that the personal history of drug use is far from being accurate. Fearing legal consequences and embarrassment of admitted illicit substance use, most users tend to deny or, to under-report illicit drug consumption. These facts have stressed an urgent need for a biological marker which does not lose its sensitivity within a few days after the end of exposure and which may yield a cumulative reflection of long term exposure to illicit drugs. Hair analysis has emerged as such a marker. A variety of illicit and medicinal compounds have been shown to be incorporated into hair including trace metals, barbiturates, amphetamines, opiates, phencyclidine, cocaine, nicotine and cannabis. Hair analysis for drugs of abuse provides long-term information on an individuals drug use; its window of detection is limited only by the length of the hair and typically, ranges from a week to several months. After establishing and validating several hair tests during the last decade, we have analyzed over 1000 hair samples for different drugs of abuse. We used RIA for screening and GC-MS for confirmation of positive results. The aim of this report is to illustrate the diagnostic usefulness of hair testing in different age groups (newborns, children, adults) and circumstances: (criminal cases, athletes, child custody cases, etc.).