Potential effect of Olea europea leaves, Sonchus oleraceus leaves and Mangifera indica peel extracts on aromatase activity in human placental microsomes and CYP19A1 expression in MCF-7 cell line: Comparative study

Aromatase inhibitors (AIs) provide novel approaches to the adjuvant therapy for postmenopausal women with estrogen-receptor-positive (ER+) breast cancers. In this study, different plant extracts from Olea europaea leaves (OLE), Sonchus oleraceus L. (SOE) and Mangifera indica peels (MPE) were prepared to identify phytoconstituents and measure antioxidant capacities. The effects of these three extracts on aromatase activity in human placental microsomes were evaluated. Additionally, the effects of these extracts on tissue-specific promoter expression of CYP19A1 gene in cell culture model (MCF-7) were assessed using qRT-PCR. Results showed a concentration-dependent decrease in aromatase activity after treatment with OLE and MPE, whereas, SOE showed a biphasic effect. The differential effects of OLE, SOE and MPE on aromatase expression showed that OLE seems to be the most potent suppressor followed by SOE and then MPE. These findings indicate that OLE has effective inhibitory action on aromatase at both the enzymatic and expression levels, in addition to its cytotoxic effect against MCF-7 cells. Also, MPE may be has the potential to be used as a tissue-specific aromatase inhibitor (selective aromatase inhibitor) and it may be promising to develop a new therapeutic agent against ER+ breast cancer.

Single dose, CYP2D6 genotype-stratified pharmacokinetic study of atomoxetine in children with ADHD

The effect of CYP2D6 genotype on the dose-exposure relationship for atomoxetine has not been well characterized in children. Children 6-17 years of age diagnosed with attention-deficit hyperactivity disorder (ADHD) were stratified by CYP2D6 genotype into groups with 0 (poor metabolizers [PMs], n = 4), 0.5 (intermediate metabolizers [IMs], n = 3), one (extensive metabolizer [EM]1, n = 8) or two (EM2, n = 8) functional alleles and administered a single 0.5 mg/kg oral dose of atomoxetine (ATX). Plasma and urine samples were collected for 24 (IM, EM1, and EM2) or 72 hours (PMs). Dose-corrected ATX systemic exposure (area under the curve [AUC]0-∞ ) varied 29.6-fold across the study cohort, ranging from 4.4 ± 2.7 μM*h in EM2s to 5.8 ± 1.7 μM*h, 16.3 ± 2.9 μM*h, and 50.2 ± 7.3 μM*h in EM1s, IMs, and PMs, respectively (P < 0.0001). Simulated steady state profiles at the maximum US Food and Drug Administration (FDA)-recommended dose suggest that most patients are unlikely to attain adequate ATX exposures. These data support the need for individualized dosing strategies for more effective use of the medication.

Plasma ghrelin and liquid gastric emptying in children with functional dyspepsia consistent with post-prandial distress syndrome

BACKGROUND

Adult studies indicate a role for ghrelin in functional dyspepsia (FD) mediated through ghrelin's effect on gastric emptying (GE). This study examines the relationship between ghrelin, liquid GE, and pain in children with FD.

METHODS

Thirteen FD patients reporting symptoms consistent with post-prandial distress syndrome (PDS) and 17 healthy controls were enrolled. All participants received a liquid meal containing (13) C-sodium acetate. Pain severity, liquid GE utilizing exhaled (13) CO2 from the sodium acetate breath tests (ABT), plasma acyl ghrelin (AG), and des-acyl ghrelin concentrations were measured at specific intervals over 240 min following ingestion.

KEY RESULTS

FD-PDS patients demonstrated lower mean baseline AG (14.8 ± 9.7 vs 27.2 ± 14.0 fmol/mL; p = 0.013), AG Cmax (24.6 ± 8.2 vs 40.5 ± 16.8 fmol/mL; p = 0.007), and AG flux (18.2 ± 7.8 vs 32.7 ± 17.3 fmol/mL; p = 0.015) than controls. The time to reach maximum exhaled (13) CO2 concentration (T max ) was longer in FD patients than controls (47.5 ± 18.5 vs 35.8 ± 11.8 min; p = 0.046). Significant relationships between ghrelin analyte ratios and ABT parameters were largely confined to control participants.

CONCLUSIONS & INFERENCES

FD-PDS in children is associated with lower fasting and maximum AG concentrations, and dampened AG flux. These data suggest a possible role for altered ghrelin physiology in the pathogenesis of PDS.

Three new cases of human infection with Dirofilaria repens, one pulmonary and two subcutaneous, in the Egyptian governorate of Assiut

Human dirofilariasis caused by Dirofilaria repens is a parasitic infection, currently considered to be an emerging zoonosis, that has been observed in many areas of the Old World. Dogs are the main 'reservoir' host. In humans, D. repens can cause inflammatory nodules, most commonly in the subcutaneous tissues or in the subconjunctival space. Lung involvement, which is the most common of the non-cutaneous and non-ocular manifestations, is frequently mis-diagnosed as a primary or metastatic lung tumour. Two new subcutaneous cases and one new pulmonary case, all observed in the Egyptian governorate of Assiut, are described here. This represents the first report of human pulmonary dirofilariasis caused by D. repens on the African continent. All the worms collected from the cases, including a living worm from the left lung of the pulmonary case, were identified morphologically, and the identity of the lung parasite was confirmed by PCR.

Considerations in the rational design and conduct of phase I/II pediatric clinical trials: avoiding the problems and pitfalls

Over the past decade, there has been a heightened awareness of the need to include children in the drug development process. With this awareness has come an expansion of the infrastructure for conducting studies in children and an increase in the sponsorship of pediatric clinical trials. However, the growth in pediatric research has, in many cases, not been accompanied by an increase in the involvement of trained pediatric investigators when it comes to trial design and/or interpretation. Pediatric phase I/II protocols continue to span a spectrum from those that are carefully constructed to those that are poorly designed. This paper highlights the basic elements of phase I/II protocols that merit unique consideration when the clinical trial involves children. Illustrations are provided from our experience, which highlight problems that may arise when trials are not designed with the pediatric patient in mind.

Identification and characterization of novel sequence variations in the cytochrome P4502D6 (CYP2D6) gene in African Americans

Cytochrome P4502D6 (CYP2D6) genotyping reliably predicts poor metabolizer phenotype in Caucasians, but is less accurate in African Americans. To evaluate discordance we have observed in phenotype to genotype correlation studies, select African American subjects were chosen for complete resequencing of the CYP2D6 gene including 4.2 kb of the CYP2D7-2D6 intergenic region. Comparisons were made to a CYP2D6(*)1 reference sequence revealing novel SNPs in the upstream, coding and intervening sequences. These sequence variations, defining four functional alleles (CYP2D6(*)41B, (*)45A and B and (*)46), were characterized for their ability to influence splice site strength, transcription level or catalytic protein activity. Furthermore, their frequency was determined in a population of 251 African Americans. A -692(TGTG) deletion (CYP2D6(*)45B) did not significantly decrease gene expression, nor could any other upstream SNP explain a genotype-discordant case. CYP2D6(*)45 and (*)46 have a combined frequency of 4% and can be identified by a common SNP. Carriers are predicted to exhibit an extensive or intermediate CYP2D6 phenotype.

Trichophyton tonsurans exocellular protease expression: correlation with clinical presentation in tinea capitis

Tinea capitis remains an overwhelmingly prevalent disease in children. Despite the fact that it was described over a century ago, disease pathogenesis remains incompletely characterized. This investigation was designed to evaluate whether inter-strain variability in fungal protease expression for clinical Trichophyton tonsurans isolates correlates with disease severity. Children with tinea capitis were enrolled and a clinical severity score (CSS) determined for all subjects by grading eight symptoms on a 4-point scale. Fungal specimens were collected by brush culture, placed in aqueous medium and incubated at 32 degrees C for 5 days. The culture supernatant was lyophilized and aliquots used to characterize protease activity. Enzyme activity, normalized to total soluble protein, varied 550-fold, 150-fold and 6-fold for collagenase, elastase and keratinase, respectively. A significant decrease in elastase and collagenase activity was observed with increasing duration of infection. In one-half of the children, CSS increased in direct response to collagenase and elastase production, while CSS was independent of enzyme activity in the remaining children. The relationship between enzyme activity and time course of disease are consistent with theories on enzyme regulation in dermatophytoses; however, the finding that two potential subsets of children exist with varied response to fungal antigens has yet to be described.

Pharmacokinetics and metabolism of oral midazolam in preterm infants

AIMS

To characterize the pharmacokinetics and metabolism of oral midazolam in 15 preterm infants.

METHODS

After an oral dose (0.1 mg kg(-1)), blood was drawn up to 24 h after administration. Midazolam and 1-OH-midazolam concentrations were determined with GC-MS. In 8 out of these 15 patients the pharmacokinetics of intravenous midazolam was also studied.

RESULTS

Apparent oral clearance, apparent volume of distribution, plasma half-life and 1-OH-Midazolam/Midazolam AUC ratio were [median (range)]: 2.7 [0.67-15.5] ml kg(-1) min(-1), 1.4 [0.3-12.1] l kg(-1), 7.6 [1.2-15.1], h and 0.03 [0.01-0.96], respectively. Absolute bioavailability was 0.49 [0.12-1.0].

CONCLUSIONS

Midazolam oral clearance is markedly decreased in preterm infants as compared with older children, probably because of immature CYP3A4 activity.

Polymorphic exocellular protease expression in clinical isolates of Trichophyton tonsurans

Tinea capitis continues to be an overwhelmingly prevalent disease in children. Despite the fact that it was recognized over a century ago, the factors that dictate the divergent clinical presentations seen with tinea capitis (e.g., carrier state, chronic non-inflammatory infection, acute severely-inflammatory infection) remain unknown. Given the pathogenic role of exocellular proteases in dermatophyte infections and their potential immunogenic role, this investigation was designed to characterize strain-specific variability in fungal protease expression and activity in Trichophyton tonsurans isolates identified from children with tinea capitis.

Concordance between tramadol and dextromethorphan parent/metabolite ratios: the influence of CYP2D6 and non-CYP2D6 pathways on biotransformation

Cytochrome P4502D6 (CYP2D6) activity has been shown to be a determinant of both the pharmacokinetics and pharmacodynamics of tramadol in adults. This study evaluated the association between CYP2D6 activity, as determined by dextromethorphan (DM) urinary metabolite ratio, and tramadol biotransformation in 13 children (7-16 years). CYP2D6 genotype was determined by XL-PCR and PCR/RFLP. Phenotype was assessed by HPLC quantitation of DM and its metabolites from a 12- to 24-hour urine collection following a single oral dose of DM. There was only a modest correlation between tramadol/M1 (metabolite 1) plasma concentration or AUC and the DM/dextrorphan (DX) urinary molar ratio in the study cohort; however, when subjects were segregated based on the number of functional CYP2D6 alleles, a much stronger relationship was observed for subjects with two functional alleles, with essentially no relationship evident in those individuals with one functional allele. Further evaluation of these data suggested that the CYP2D6-mediated metabolite (M1) is formed to a lesser extent, and the formation of the non-CYP2D6 product (M2) is more pronounced in subjects with one versus two functional alleles. Thus, the number of functional CYP2D6 alleles and the availability of alternative cytochromes P450 capable of metabolizing tramadol may explain the poor association between DM, a well-characterized CYP2D6 probe, and tramadol in a population of CYP2D6 extensive metabolizers.

Pharmacokinetics and metabolism of intravenous midazolam in preterm infants

BACKGROUND

Midazolam, a benzodiazepine, is finding expanded use in neonatal intensive care units. We studied the pharmacokinetics and metabolism of midazolam after a single intravenous dose in preterm infants.

METHODS

The pharmacokinetics of midazolam and its hydroxylated metabolite (1-OH-midazolam) after a single 0.1 mg/kg intravenous dose of midazolam were determined in 24 preterm infants (gestational age, 26 to 34 weeks; postnatal age, 3 to 11 days). Blood samples were obtained before drug administration and at 0.5, 1, 2, 4, 6, 12, and 24 hours after the start of the infusion. Midazolam and 1-OH-midazolam concentrations were determined by use of gas chromatography-mass spectrometry.

RESULTS

Total body clearance, apparent volume of distribution, and plasma half-life of midazolam were (median [range]): 1.8 (0.7-6.7) ml/kg per min, 1.1 (0.4-4.2) L/kg, and 6.3 (2.6-17.7) h, respectively. In 19 of 24 preterm infants, 1-OH-midazolam concentrations could be detected: 1-OH-midazolam (1-OH-M) maximal concentration of drug in plasma (C(max)), time to reach C(max) (T(max)), and 1-OH-M/M area under the concentration-time curve from time zero to the last sampling time point (AUC(0-t)) ratio were [median (range)]: 8.2 (<0.5-68.2) ng/ml, 6 (1-12) h, and 0.09 (<0.001-1), respectively. Midazolam plasma clearance was increased in those infants who had indomethacin (INN, indometacin) exposure.

DISCUSSION

Consequent to immature hepatic cytochrome P450 3A4 (CYP3A4) activity, midazolam clearance and 1-OH-midazolam concentrations are reduced markedly in preterm infants as compared to concentrations in previous reports from studies in older children and adults. Indomethacin exposure and its apparent impact on midazolam clearance support alteration of drug disposition produced by a patent ductus arteriosus or by the direct effects of indomethacin on hemodynamic or renal function.

Sucrose analgesia for minor procedures in newborn infants

OBJECTIVE

To evaluate the role of intraoral sucrose and other sweet-tasting solutions for the management of pain associated with minor procedures in newborns.

DATA SOURCES

A search of MEDLINE articles from 1966 to August 1999 and an extensive review of journals was conducted. MeSH headings included analgesia, sucrose, and neonate.

DATA SYNTHESIS

Newborn infants regularly undergo minor invasive procedures for which analgesics are not routinely used. Intraoral sucrose and other sweet-tasting solutions appear to diminish surrogate biomarkers of pain response as evidenced by a reduction in crying time, smaller increases in heart rate, and lower pain scale ratings.

CONCLUSIONS

These studies appear to suggest that sucrose solution 0.5 g provides effective analgesia with no reported adverse effects.

Histopathological studies on neoplasms in the genital tract of female donkeys in Egypt

The genital tracts of 165 female donkeys were collected and examined with special concern to neoplasms. Ovarian Neoplasms were found in 12 cases (7.72%). A granulosa cell tumor was found in one case (0.61%). A cavernous haemangioma was found in 11 cases (6.67%). Uterine neoplasms were found in 14 cases (8.84%). Endometrial polyps and fibroleiomyoma were found in one case (0.61%) each. Leiomyoma was found in 2 cases (1.21%). Cavernous haemangioma was found in 10 cases (6.06%), and cervical polyps in 5 cases (3.03%).

Single dose pharmacokinetics of linezolid in infants and children

BACKGROUND

Linezolid is an oxazolidinone antibiotic with excellent in vitro activity against a number of Gram-positive organisms including antibiotic-resistant isolates. The safety and pharmacokinetics of intravenously administered linezolid were evaluated in children and adolescents to examine the potential for developmental dependence on its disposition characteristics.

METHODS

Fifty-eight children (3 months to 16 years old) participated in this study; 44 received a single 1.5-mg/kg dose and 14 received a single 10-mg/kg dose of linezolid administered by intravenous infusion. Repeated blood samples (n = 10 in children > or = 12 months; n = 8 in children 3 to 12 months) were obtained during 24 h after drug administration, and linezolid was quantitated from plasma by high performance liquid chromatography with mass spectrometry detection. Plasma concentration vs. time data were evaluated with a model independent approach.

RESULTS

Linezolid was well-tolerated by all subjects. The disposition of linezolid appears to be age-dependent. A significant although weak correlation between age and total body clearance was observed. The mean (+/- SD) values for elimination half-life, total clearance and apparent volume of distribution were 3.0 +/- 1.1 h, 0.34 +/- 0.15 liter/h/kg and 0.73 +/- 0.18 liter/kg, respectively. Estimates of total body clearance and volume of distribution were significantly greater in children than historical values of adult data. As such maximum achievable linezolid plasma concentrations were slightly lower in children, and concentrations 12 h after a single 10-mg/kg dose were below the MIC90 for selected pathogens with in vitro susceptibility to the drug.

CONCLUSION

Based on these data a linezolid dose of 10 mg/kg given two to three times daily would appear appropriate for use in pediatric therapeutic clinical trials of this agent.

Voriconazole: a new triazole antifungal

OBJECTIVE

To review the currently available information on the pharmacology, pharmacokinetics, efficacy, adverse effects, drug interactions, and dosage guidelines of voriconazole. Comparative data for voriconazole and other azole antifungal agents are described where available.

DATA SOURCES

A MEDLINE search restricted to English-language articles (1966 to September 1999) was conducted, and an extensive review of journals and meeting abstracts was performed. MeSH headings included itraconazole, fluconazole, voriconazole, UK-109,496, and amphotericin B.

DATA EXTRACTION

The data on pharmacokinetics, adverse effects, and drug interactions were obtained from open-label and controlled studies and case reports. Controlled studies and case reports were evaluated to demonstrate the efficacy of voriconazole in treatment of various fungal infections.

DATA SYNTHESIS

Voriconazole is a derivative of fluconazole that demonstrates enhanced in vitro activity against existent and emerging fungal pathogens. Limited data have revealed a favorable pharmacokinetic and safety profile for the agent. Moreover, select clinical trials and case studies of voriconazole suggest good in vivo efficacy against several fungal pathogens including Candida, Aspergillus, and Scedosporium.

CONCLUSIONS

Voriconazole has shown promise in the treatment of superficial and systemic mycoses. While several unresolved issues remain, voriconazole may be a viable therapeutic alternative for fluconazole-resistant mucocutaneous candidiasis and in cases of mild to moderate systemic mycoses requiring chronic treatment or that are refractory to currently available agents.

Single dose pharmacokinetics of pleconaril in neonates. Pediatric Pharmacology Research Unit Network

BACKGROUND

Pleconaril is an orally active, broad spectrum antipicornaviral agent with activity against nonpolio enteroviruses. Pleconaril phamacokinetics was evaluated in 16 neonates (16.4 +/- 8.7 days postnatal age) with suspected enteroviral infection.

METHODS

Pleconaril (5 or 7.5 mg/kg) was administered orally to study subjects and plasma pleconaril concentrations quantified from serial blood samples obtained during 24 h after a single oral dose by gas chromatography with electrochemical detection. Pharmacokinetic parameter estimates were determined by noncompartmental methods and compared between doses and with similar data obtained from a previous study of pleconaril disposition in children (n = 18, 2 to 12 years).

RESULTS

Pleconaril was well-tolerated in all neonates without discernible adverse events. Comparison between the 5.0- and 7.5-mg/kg doses revealed no significant differences in peak plasma concentration (Cmax 686.7 vs. 617.1 ng/ml), elimination half-life (t 1/2; 4.6 vs. 6.6 h), area under the plasma concentration vs. time curve (AUC; 5162.6 vs. 5523.9 ng/ml/h), apparent steady state volume of distribution (V(dss)/F; 9.3 vs. 17.1 liters/ kg) and apparent oral clearance (Cl/F; 1.3 vs. 1.7 liters/h/kg). In addition, no correlation was observed between postconceptional age and AUC, V(dss)/F, t 1/2 or Cl/F for pleconaril. Comparison of pleconaril pharmacokinetics between neonates and children suggested a significant difference in V(dss)/F (9.3 vs. 4.7 liters/kg), dose-normalized Cmax, (686.7 vs. 1272.5 ng(ml) and AUC (5125.6 vs. 8131.2 ng/ml/h). In contrast, the mean elimination t 1/2 between neonates and children was not appreciably different.

CONCLUSIONS

The apparent age-dependent differences in the pharmacokinetics of pleconaril may in part be related to increased bioavailability of the drug in older children and adults than in neonates. Our data appear to support the use of a 5.0-mg/kg dose given every 8 to 12 h in future studies of pleconaril in neonatal patients with enteroviral infection.

An investigation of the intradermal route as an effective means of immunization for microparticulate vaccine delivery systems

Among the common routes of parenteral immunization, the skin is the only site that can function as an immune organ. Skin-associated lymphoid tissue contains specialized cells that enhance the immune response. The intercellular space in the skin interstitium provides a connection to the lymphatic capillaries and vessels that terminate in peripheral immune organs like the lymph nodes and spleen. The potential of intradermal immunization with microparticulate vaccine delivery systems was investigated in this study. The microparticulates used were muramyl dipeptide (MDP) loaded ovalbumin microspheres (OVA-MSs) and fluorescent latex microspheres of fixed sizes of 2.3 and 2.1 microm diameter, respectively. Similar doses of OVA-MSs were injected subcutaneously (s.c.) and intradermally (i.d.) in mice. The induced OVA-specific IgG antibody immune response was found to be significantly higher in i.d. immunized mice as compared to those injected s.c. The sc and i.d. administration of fluorescent latex microspheres in mice demonstrated that the uptake and translocation of microspheres from the site of injection depends primarily upon the surface area of the microspheres. The enhancement in antibody production upon i.d. administration was explained on the basis of (i) an increased surface area of microspheres and a lower number of microspheres per injection site, and (ii) an increased probability of interaction with the immune cells of the skin. Efficient lymph node targeting observed from the id administered microspheres may be the result of both of these factors. The results of this study demonstrated that the intradermal route is an effective means of immunization for microparticulate vaccine delivery systems, requiring lower doses and resulting in a higher immune response as compared to the traditionally used sc route.

Cerebrospinal fluid pharmacokinetics of cefpodoxime proxetil in piglets

Cefpodoxime is an oral third-generation cephalosporin used for the treatment of acute upper-respiratory tract infections caused by susceptible bacteria in children. Although not indicated for the treatment of bacterial meningitis, it is used to treat other infections produced by organisms associated with meningitis and may obscure the result of cerebrospinal fluid (CSF) cultures in children who develop meningitis while receiving oral antibiotics if sufficient concentrations are achieved in the CSF. This study evaluated the disposition of cefpodoxime and penetration into CSF in piglets. Fifteen Landacre-Camborough cross piglets (10-20 days old) received cefpodoxime proxetil oral suspension (10 mg/kg). Repeated plasma and CSF samples were collected over 24 hours for quantitation of cefpodoxime by HPLC. Pharmacokinetic analysis was performed on both plasma and CSF data. The plasma concentration versus time data for cefpodoxime were best characterized using a one-compartment model with first-order absorption. The mean (+/- SD) pharmacokinetic parameters for Cmax, tmax, and AUC0-infinity were 23.3 +/- 12.9 mg/L, 3.9 +/- 1.4 h, and 237 +/- 129 mg/L.h, respectively. CSF/plasma ratios for AUC0-infinity demonstrated a mean cefpodoxime penetration of approximately 5%. CSF penetration of cefpodoxime was evident following a single oral dose of cefpodoxime proxetil suspension. Despite the small percentage of total cefpodoxime dose distributing into the CSF, the resultant concentrations approached or exceeded the MIC90 for many bacterial pathogens considered susceptible to cefpodoxime. Accordingly, clinicians should use caution in the interpretation of CSF cultures in patients who develop clinical signs and symptoms consistent with meningitis and who have been previously treated with cefpodoxime.

Potent inhibition of cytochrome P-450 2D6-mediated dextromethorphan O-demethylation by terbinafine

Cytochrome P-450 (CYP) 2D6 is responsible for the biotransformation of over 35 pharmacologic agents. In the process of studying CYP2D6 we identified phenotype-genotype discordance in two individuals receiving terbinafine. This prompted evaluation of the potential for terbinafine to inhibit CYP2D6 in vitro. Human hepatic microsomes and heterologously expressed CYP2D6 were incubated with terbinafine or quinidine and the formation of dextrorphan from dextromethorphan was determined by HPLC. Additionally, preliminary conformational analyses were conducted to determine the fit of terbinafine into a previously described pharmacophore model for CYP2D6 inhibitors. The apparent Km and Vmax of dextrorphan formation from four human hepatic microsome samples ranged from 5.8 to 6.8 microM and from 172 to 300 pmol/min/mg protein, respectively. Values of Km and Vmax in the heterologously expressed CYP2D6 system averaged 6.5 +/- 2.1 microM and 1342 +/- 147 pmol/min/mg protein, respectively. Terbinafine inhibited dextromethorphan O-demethylation with an apparent Ki ranging from 28 to 44 nM in human hepatic microsomes and averaging 22.4 +/- 0.6 nM for the heterologously expressed enzymes. Results of quinidine in these systems produced values for Ki ranging from 18 to 43 nM. Such strong inhibition of CYP2D6 by terbinafine would not have been predicted by the previously proposed pharmacophore model of CYP2D6 inhibitors based on molecular structure. Terbinafine is a potent inhibitor of CYP2D6 with apparent Ki values well below plasma and tissue concentrations typically achieved during a therapeutic course. This agent needs to be evaluated in vivo to determine the impact of CYP2D6 inhibition by terbinafine on the metabolism of concomitantly administered CYP2D6 substrates.

Single oral dose escalation pharmacokinetics of pleconaril (VP 63843) capsules in adults

Pleconaril is an orally active broad-spectrum antipicornaviral agent with excellent penetration into the central nervous system and nasal epithelium. The authors report the results of a randomized, placebo-controlled, dose escalation study of pleconaril oral capsules following single-dose administration of 50 to 1000 mg. Fifty-six healthy adults (ages 19-55) participated in the study. Each subject received a single dose of pleconaril oral capsule(s) or an identically matched placebo. Blood samples (n = 19) were obtained over 36 hours postdose, and pleconaril was quantified from plasma by gas chromatography. Pleconaril disposition was best characterized using a two-compartment open-model with first-order absorption. Fifty-five subjects completed the study (31 +/- 10 years, 77.6 +/- 11 kg). The administration of pleconaril was well tolerated. There was no difference in tmax, lambda z, ka, t1/2elim, Cl/F, or Vdss/F among the various dose groups. A significant difference in both Cmax and AUC was observed between study groups; however, this difference became insignificant when the parameters were corrected for dose. Cmax and AUC were dose proportional between 50 and 1000 mg (r2 > 0.97 and 0.90, respectively). Pleconaril demonstrates a favorable safety and pharmacokinetic profile following single-dose administration.

Investigation of terbinafine as a CYP2D6 inhibitor in vivo

BACKGROUND

Terbinafine is an orally active antifungal used in the treatment of dermatophytoses. To date, studies evaluating the effect of terbinafine on the cytochromes P450 have failed to show any significant interactions. This prospective open-label study was designed to confirm our previous finding that terbinafine may inhibit CYP2D6.

METHODS

Nine healthy volunteers were enrolled in this study-6 genotypically consistent with an extensive metabolizer phenotype and 3 genotypic poor metabolizers for CYP2D6. The change in CYP2D6 enzyme activity before (x 3) and after (monthly x 6 months) administration of terbinafine (250 mg once daily x 14 days) was evaluated with the dextromethorphan to dextrorphan urinary metabolite ratios. On each study day a predose urine sample was collected, 0.3 mg/kg dextromethorphan was administered, and urine was collected for 24 hours. Dextromethorphan and its metabolites were quantified from urine by HPLC.

RESULTS

Baseline phenotype values were concordant with individual genotype. In all extensive metabolizers, the administration of terbinafine resulted in a dramatic increase in the dextromethorphan/dextrorphan ratio, converting 4 of the 6 extensive metabolizers into phenotypic poor metabolizers. On average, a 97-fold increase in ratio (range, 35 to 265) was observed for extensive metabolizers after the administration of terbinafine. No significant change was observed in the metabolite ratios of poor metabolizers during the course of the study.

CONCLUSIONS

Terbinafine inhibits CYP2D6 sufficiently to produce a discordance between genotype and phenotype for the enzyme. The dextromethorphan/dextrorphan metabolite ratios increased in all individuals, with otherwise functional CYP2D6 activity. The disposition of CYP2D6 substrates coadministered with terbinafine may be significantly altered in extensive metabolizers for this cytochrome P450 isoform, who comprise approximately 93% of the population.

Stability of fumagillin in an extemporaneously prepared ophthalmic solution

The stability of fumagillin 70 microg/mL (as the bicyclohexylammonium crystal) in an extemporaneously prepared ophthalmic solution was studied. An ophthalmic solution of fumagillin 70 microg/mL was prepared by combining 120 mg of fumagillin bicyclohexylammonium crystals with 20 mL of 0.9% Sodium Chloride Injection, USP, and 20 mL of an ophthalmic irrigating solution. The solution was stored in 12 sterile semi-opaque dropper bottles; 4 bottles were stored at 25 degrees C exposed to light, 4 were stored at 25 degrees C in the dark, and 4 were stored at 4 degrees C in the dark. Samples were taken on days 0, 7, 14, 21, and 28 and analyzed by high-performance liquid chromatography. Sterility was tested as well. In the solutions stored at 25 degrees C, 17-30% of the initial drug concentration was lost during the first week. The solution protected from light and stored at 4 degrees C lost about 12% of active drug by week 4. There was no change in color or odor in any of the solutions and only a minor change in pH over the study period. There was no evidence of microbial growth in any of the solutions tested. Fumagillin 70 microg/mL (as the bicyclohexylammonium crystal) in 0.9% sodium chloride injection and an ophthalmic irrigating solution containing benzalkonium chloride was stable in the dark for 14 days at 4 degrees C.

Single-dose pharmacokinetics of a pleconaril (VP63843) oral solution in children and adolescents. Pediatric Pharmacology Research Unit Network

Pleconaril is an orally active, broad-spectrum antipicornaviral agent which demonstrates excellent penetration into the central nervous system, liver, and nasal epithelium. In view of the potential pediatric use of pleconaril, we conducted a single-dose, open-label study to characterize the pharmacokinetics of this antiviral agent in pediatric patients. Following an 8- to 10-h period of fasting, 18 children ranging in age from 2 to 12 years (7.5 +/- 3.1 years) received a single 5-mg/kg of body weight oral dose of pleconaril solution administered with a breakfast of age-appropriate composition. Repeated blood samples (n = 10) were obtained over 24 h postdose, and pleconaril was quantified from plasma by gas chromatography. Plasma drug concentration-time data for each subject were fitted to the curve by using a nonlinear, weighted (weight = 1/Ycalc) least-squares algorithm, and model-dependent pharmacokinetic parameters were determined from the polyexponential parameter estimates. Pleconaril was well tolerated by all subjects. A one-compartment open-model with first-order absorption best described the plasma pleconaril concentration-time profile in 13 of the subjects over a 24-h postdose period. Pleconaril pharmacokinetic parameters (means +/- standard deviations) for these 13 patients were as follows. The maximum concentration of the drug in serum (Cmax) was 1,272.5 +/- 622.1 ng/ml. The time to Cmax was 4.1 +/- 1.5 h, and the lag time was 0.75 +/- 0.56 h. The apparent absorption rate constant was 0.75 +/- 0.48 1/h, and the elimination rate constant was 0.16 +/- 0.07 1/h. The area under the concentration-time curve from 0 to 24 h was 8,131.15 +/- 3,411.82 ng.h/ml. The apparent total plasma clearance was 0.81 +/- 0.86 liters/h/kg, and the apparent steady-state volume of distribution was 4.68 +/- 2.02 liters/kg. The mean elimination half-life of pleconaril was 5.7 h. The mean plasma pleconaril concentrations at both 12 h (250.4 +/- 148.2 ng/ml) and 24 h (137.9 +/- 92.2 ng/ml) after the single 5-mg/kg oral dose in children were higher than that from in vitro studies reported to inhibit > 90% of nonpolio enterovirus serotypes (i.e., 70 ng/ml). Thus, our data support the evaluation of a 5-mg/kg twice-daily oral dose of pleconaril for therapeutic trials in pediatric patients with enteroviral infections.

Stability of terbinafine hydrochloride in an extemporaneously prepared oral suspension at 25 and 4 degrees C

The stability of terbinafine 25 mg/mL (as the hydrochloride salt) in an extemporaneously prepared oral suspension at 25 and 4 degrees C was studied. Twenty 250-mg terbinafine tablets were crushed to a fine powder and diluted to a concentration of 25 mg/mL with sweetened vehicle. The suspension was stored in amber polyethylene prescription bottles at 25 or 4 degrees C. Samples were taken on days 0, 7, 14, 28, 42, 56, 70, and 91 for duplicate analysis of terbinafine content by high-performance liquid chromatography and to observe any changes in color and odor; pH was measured as well. Through the initial 42 days, the mean concentration of terbinafine in the samples stored at both temperatures was >93% of the initial concentration; by day 56, the mean concentration was <88%. No appreciable changes in color or odor were observed during the study period. The apparent pH of the suspension decreased slightly over the 91 days, from an initial 5.6 to 5.5. Terbinafine 25 mg/mL (as the hydrochloride salt) in an extemporaneously prepared oral suspension was stable for up to 42 days in polyethylene prescription bottles at 25 and 4 degrees C.

Single-dose pharmacokinetics of a pleconaril (VP63843) oral solution and effect of food

Pleconaril is an orally active broad-spectrum antipicornaviral agent which demonstrates excellent penetration into the central nervous system, liver, and nasal epithelium. We report the results of a randomized two-way crossover study designed to characterize the disposition of a single dose (200 mg) of pleconaril oral solution in fed and fasting humans. Twelve healthy adult subjects (18.7 to 39 years of age) participated in this study. Each subject received a single 200-mg dose of pleconaril oral solution, both coadministered with a standard English breakfast and following a 10-h predose fast. There was a minimum 7-day washout period between pleconaril doses. Repeated blood samples (n = 10) were obtained over 24 h postdose, and the pleconaril level in plasma was quantified by gas chromatography. Plasma concentration-versus-time data were curve fitted for each subject by using a nonlinear weighted least-squares algorithm, and pharmacokinetic parameters were determined from the polyexponential estimates. Pleconaril disposition was best characterized by a one-compartment open model with first-order absorption. The apparent bioavailability of pleconaril oral solution was significantly increased with the administration of food. The area under the concentration-time curve and maximum concentration of pleconaril in plasma achieved following the standard English breakfast (i.e., 9.08 +/- 3.23 mg/liter . h and 1.14 +/- 0.58 mg/liter, respectively) were 2.2- and 2.5-fold higher, respectively than those achieved in the fasting state (i.e., 4.08 +/- 2.74 mg/liter . h and 0.46 +/- 0.30 mg/liter, respectively). Mean plasma pleconaril concentrations 12 h after a single 200-mg oral dose (fed, 0.25 +/- 0.2 mg/liter; fasting, 0.11 +/- 0.10 mg/liter) in healthy adults remained greater than that required to inhibit more than 90% of the enteroviruses in cell culture (i.e., 0.07 mg/liter). To enhance the oral bioavailability of pleconaril, coadministration with a fat-containing meal is recommended.

Cefpodoxime pharmacokinetics in children: effect of food

BACKGROUND

Cefpodoxime, an oral third generation cephalosporin antibiotic, is used for the treatment of acute upper respiratory tract infection caused by susceptible bacteria in children 5 months to 12 years of age. We report the results of a randomized two-way crossover study designed to characterize the disposition of a single dose (10 mg/kg) of cefpodoxime proxetil oral suspension in children, under fed and fasted conditions.

METHODS

Seventeen children (8.4 months to 12.2 years old, seven female) participated in this study. Each subject received a single 10-mg/kg dose of cefpodoxime proxetil oral suspension, after a predose fast and again coadministered with food. Repeated blood samples (n=10) were obtained during 12 h postdose and cefpodoxime was quantified from plasma by high performance liquid chromatography. Plasma concentration vs. time data were curve fit for each subject with a nonlinear weighted least squares algorithm, and pharmacokinetic parameters were determined from the polyexponential estimates.

RESULTS

Cefpodoxime disposition was best characterized using a one-compartment open model with first order absorption. The area under the plasma concentration vs. time curve, Cmax and Ke were not significantly different between fed and fasted conditions. However, Tmax was significantly prolonged (fed=2.79+/-1.10 h vs. fasted=1.93+/-0.54 h) and Ka was significantly smaller (fed=0.42+/-0.14 h(-1) vs. fasted=0.81+/-0.72 h(-1)) in the fed state.

CONCLUSIONS

Administration of cefpodoxime in the presence of food affected the rate but not the extent of absorption. Cefpodoxime proxetil oral suspension can be administered without regard to meals in children 6 months to 12 years of age.

Evaluation of a diagnostic monoclonal antibody-based capture enzyme-linked immunosorbent assay for detection of a 26- to 28-kd Fasciola hepatica coproantigen in cattle

OBJECTIVE

To develop a monoclonal antibody-based capture ELISA for detection of a 26- to 28-kd coproantigen of Fasciola hepatica in the feces of infected cattle.

ANIMALS

27 crossbred yearling calves, 2 New Zealand White rabbits.

PROCEDURE

A capture ELISA that uses a previously described monoclonal antibody (MAB) M2D5/D5F10 was developed. The MAB was used to capture the antigen from the feces, and hyperimmune rabbit serum raised against the purified 26- to 28-kd glycoprotein was used to detect the coproantigen. This test was used for the detection of the antigen in the feces of 27 experimentally infected calves with known numbers of flukes. Fecal specimens obtained before infection from the same calves were used as negative controls.

RESULTS

The assay results identified all calves infected with more than 10 flukes at necropsy, and as little as 300 pg of coproantigen/ml of fecal supernatant was detected. The assay results correlated well with the number of flukes, suggesting that it is possible to estimate fluke burden. Infections as early as 6 weeks duration were detected, before flukes mature to adults and start to shed eggs.

CONCLUSIONS

In experimentally infected calves, the coproantigen capture ELISA was more sensitive and easier to perform than microscopic examination for the diagnosis of F hepatica infection; moreover, 6-week-old prepatent infections were detectable.

CLINICAL RELEVANCE

This capture ELISA containing an F hepatica 26- to 28-kd coproantigen is a quantitative assay that is more sensitive than fecal egg counting. In addition, the assay is rapid, easy to perform and lends itself well to large numbers of samples. Because it is antigen based, the ELISA may be useful for diagnosis of F hepatica infection in other species, including human beings.

Efficacy of itraconazole in children with Trichophyton tonsurans tinea capitis

BACKGROUND

Tinea capitis is prevalent in children. Although widely used as the drug of choice, the response to griseofulvin may be incomplete and an extended duration of therapy is often required. The response to newer antifungals has not been methodically evaluated in children with Trichophyton tonsurans infection.

OBJECTIVE

Our purpose was to determine the efficacy of itraconazole in children with tinea capitis caused by T. tonsurans.

METHODS

Pediatric patients with culture proven tinea capitis were enrolled from a hospital-based primary care clinic between January and December of 1996. Patients were treated with itraconazole 100 mg/day and a selenium sulfide-containing shampoo for 4 weeks. Children were evaluated mycologically and clinically every 2 weeks for 2 months. Patients were considered successfully treated if they were culture negative and clinically improved at the end of the study period. Children who remained culture positive or who were clinically not improved at 2 months were classified as treatment failures and retreated.

RESULTS

Twenty-five patients completed the study, and 10 (40%) were successfully treated. Fifteen children required re-treatment: 14 remained culture positive at week 8, and one was mycologically negative but clinically worse.

CONCLUSION

Itraconazole at a dose of 100 mg/day for 4 weeks may be effective in less than half of children with T. tonsurans tinea capitis.

Guidelines for the treatment of Helicobacter pylori in the pediatric population

Several factors including long-term eradication of the organism, cost, compliance, and adverse event profile should be considered for treating H. pylori infection in pediatric patients. Triple therapy with bismuth, tetracycline, and metronidazole is considered the gold standard for adult patients; however, tetracyclines are not recommended in children younger than 8 years due to the potential for tooth discoloration and alterations in bone growth. Dual and shorter duration of therapy should be evaluated in children with H. pylori. The new dual therapy omeprazole/clarithromycin regimens approved by the Food and Drug Administration for adults may be considered as an alternative for children when concerns include the use of salicylates or allergy to beta-lactams. Although the dosage of omeprazole in pediatric patients has not been established (no pediatric formulation exists), clarithromycin is available for use in pediatric patients. However, these drugs cannot be recommended for children with H. pylori until additional studies in this population are available. Based on the available data, aminopenicillin/bismuth or aminopenicillin/tinidazole combinations appear to be effective in eradicating H. pylori in children. Amoxicillin 50 mg/kg/d plus bismuth subsalicylate (< 10 y, 262 mg; > 10 y, 525 mg qid) or bismuth subcitrate (< 12 y, 120 mg; > 12 y, 240 mg bid) can be used for 6 weeks. The bismuth dosages represented above were those used in various studies. It should be realized, however, that a definitive dosage of bismuth subsalicylate for children in the treatment of H. pylori has not been established. The adult dosage of bismuth subsalicylate for the eradication of H. pylori is the same as that used for prophylaxis in diarrhea (525 mg qid). When dosage of this agent is unknown (particularly for the treatment of very young children), the use of established dosages for prophylaxis in diarrhea may be considered for treating H. pylori. Additionally, bismuth subsalicylate should be used with caution in children with suspected viral infections (i.e., to prevent Reye's syndrome) or those receiving concurrent therapy with interacting drugs. If available, tinidazole 20 mg/kg/d can be used with amoxicillin 50 mg/kg/d for 6 weeks to treat children infected with H. pylori.

Oral terbinafine: a new antifungal agent

OBJECTIVE

To review the pharmacology, pharmacokinetics, efficacy, adverse effects, drug interactions, and dosage guidelines of terbinafine. Available comparative data of terbinafine and other antimycotic agents are described for understanding the potential role of terbinafine in patient care.

DATA SOURCES

A MEDLINE search restricted to English language during 1966-1996 and extensive review of journals was conducted to prepare this article. MeSH headings included allylamines, terbinafine, SF 86-327, dermatophytosis, dermatomycosis.

DATA EXTRACTION

The data on pharmacokinetics, adverse effects, and drug interactions were obtained from open-label and controlled studies and case reports. Controlled single- or double-blind studies were evaluated to describe the efficacy of terbinafine in the treatment of various fungal infections.

DATA SYNTHESIS

Terbinafine is the first oral antimycotic in the allylamines class: a fungicidal agent that inhibits ergosterol synthesis at the stage of squalene epoxidation. Terbinafine demonstrates excellent in vitro activity against the majority of dermatophyte species including Trichophyton rubrum, Trichophyton mentagrophytes, and Epidermophyton floccosum; less activity is seen against Dematiaceae and the filamentous fungi. It is least active against the pathogenic yeast and this correlates with the relatively poor efficacy against these organisms in vivo. High concentrations of terbinafine are achieved in keratinous tissues, the site of superficial infections, and these concentrations are maintained for up to 3 months. The clinical efficacy of terbinafine against a number of dermatophyte infections exceeds that of the current standard of therapy, griseofulvin. The efficacy of terbinafine may be as good or better than that of the azole antifungals. Additional studies are required to confirm these observations. Terbinafine demonstrates a good safety profile, and relatively few drug interactions have been identified.

CONCLUSIONS

Terbinafine is more effective than the gold standard, griseofulvin, in the treatment of tinea pedis and tinea unguinum, with considerably shorter treatment duration in the latter. It has been proven as effective as griseofulvin in the treatment of tinea capitis, tinea corporis, and tinea cruris. Terbinafine does not appear to offer any advantage in the treatment of nondermatophyte infections; its utility in the treatment of systemic infections has yet to be established. Depending on individual institutional costs, terbinafine may be a front-line drug for some superficial infections responding poorly to the current standard of therapy.

Response to initial griseofulvin therapy in pediatric patients with tinea capitis

OBJECTIVE

To estimate the response rate to initial griseofulvin therapy in pediatric patients with tinea capitis and to determine whether clinical or epidemiologic variables differed between patients responding positively and negatively to therapy.

METHODS

A review of patients' medical records with a confirmed diagnosis of tinea capitis was performed retrospectively over a 2-year period. Patients were included only if a positive dermatophyte culture was obtained and the initial prescription for griseofulvin was filled at our pharmacy. Responders were children not returning to the clinic or returning without signs or symptoms of infection. Nonresponders were those returning within 8 months with signs and symptoms of disease, requiring additional therapy.

RESULTS

During July 1993-June 1995, 479 positive fungal cultures were confirmed in 474 patients, and 857 prescriptions for griseofulvin were filled for 765 patients at our institution. Of 122 evaluable patients meeting both criteria, 60.7% were classified as responders to initial prescribed therapy. The remaining 39.3% returned to the clinic within 8 months of initial therapy, requiring additional treatment. An additional 10.7% had a recurrence at a later date. There was no correlation between clinical response and dosage, age, race, or gender, although there was a trend toward longer treatment duration among responders.

CONCLUSIONS

It is evident that tinea capitis persists in the urban pediatric population. Our data suggest that griseofulvin, the current drug of choice, may be ineffective in at least one-third of pediatric patients with tinea capitis.

Treatment of tinea capitis

OBJECTIVE

To review the epidemiology, pathogenesis, mycology, clinical presentation, and pharmacotherapy of tinea capitis, and describe the role of newer antimycotic agents.

DATA SOURCES

A MEDLINE search restricted to English-language articles published from 1966 through 1996 and journal references were used in preparing this review.

DATA EXTRACTION

The data on mycology, pharmacokinetics, adverse effects, and drug interactions were obtained from controlled studies and case reports appearing in the literature. Both open-label and comparative studies were evaluated to assess the efficacy of antimycotics in the treatment of this infection.

DATA SYNTHESIS

Griseofulvin is the drug of choice in the treatment of tinea capitis. Newer agents with greater efficacy or shorter treatment durations continue to be explored. Ketoconazole, the first azole studied for efficacy in tinea capitis, has not demonstrated any clinical advantage over griseofulvin in several controlled clinical trials. Itraconazole is effective, but the available data are limited to case reports and a single uncontrolled study. Terbinafine similarly has shown promise in the treatment of tinea capitis, but the oral formulation was only recently approved in the US. Existing studies reflect the results in infection with pathogens not seen in the US. Both itraconazole and terbinafine achieve high concentrations in the hair and stratum corneum that persist for several weeks following drug administration. This may enable shorter courses of therapy; however, comparative studies need to be conducted in the US.

CONCLUSIONS

Tinea capitis remains the most common dermatophyte infection in young urban children. Oral antifungal therapy is required for effective treatment, often for several months. The combination of griseofulvin with a selenium sulfide shampoo continues to be the mainstay of therapy until more experience is gained with the newer antimycotics.

Dirithromycin: a new macrolide

OBJECTIVE

To review the clinical microbiology and therapeutic use of dirithromycin, emphasizing comparative data between dirithromycin and the standard macrolide erythromycin, as well as clarithromycin and azithromycin.

DATA SOURCES

A MEDLINE search of English-language literature during the years 1966-1996, and an extensive review of journals were conducted to prepare this article.

DATA EXTRACTION

The data on pharmacokinetics, adverse effects, and drug interactions were obtained from open and controlled studies. Controlled single- or double-blind studies were evaluated to assess the efficacy of dirithromycin in the treatment of various upper and lower respiratory tract infections, as well as skin and soft tissue infections.

DATA SYNTHESIS

The spectrum of activity of dirithromycin is similar to that of erythromycin, clarithromycin, or azithromycin, with some notable exceptions. Dirithromycin was more active in vitro against Campylobacter jejuni and Borrelia burgdorferi than was erythromycin or clarithromycin, but in general demonstrated less activity than erythromycin, clarithromycin, or azithromycin against a majority of microorganisms. The pharmacokinetic profile of dirithromycin offers the advantages of once-daily dosing and high and prolonged tissue concentrations; dosing adjustments are not needed in the elderly or in patients with renal or mild hepatic impairment. Clinical efficacy and bacteriologic eradication rates with dirithromycin and erythromycin are comparable for the treatment of respiratory and skin and soft tissue infections due to susceptible pathogens. Dirithromycin appears to have adverse effect profiles similar to those of the other macrolides, with reported problems most often related to the gastrointestinal tract. Dirithromycin does not seem to cause clinically important interactions with drugs such as theophylline, oral contraceptives, cyclosporine, or terfenadine.

CONCLUSIONS

Dirithromycin offers some attractive pharmacokinetic properties. The long elimination half-life of dirithromycin allows once-daily dosing and higher and more prolonged tissue concentrations than are achievable with erythromycin. The spectrum of activity, adverse effect profile, clinical efficacy, and bacteriologic eradication rate of dirithromycin may be similar to those of erythromycin. No significant drug interactions with dirithromycin have been reported. Based on available data, dirithromycin may not offer any unique clinical advantage over clarithromycin or azithromycin. Future clinical trials may reveal a special role for dirithromycin in patient care.

Protein-bound pyrroles in rat hair following subchronic intraperitoneal injections of 2,5-hexanedione

Studies were initiated to ascertain whether body hair could be used to develop a biological marker for chronic exposure to industrial neurotoxicants that yield the metabolite 2,5-hexanedione (2,5-HD), that is, n-hexane and methyl n-butyl ketone. Rats were injected daily with a 50 mg/kg ip dose of 2,5-HD for 45 d. At intervals, body hair and individual vibrissae were removed (under general anesthesia) and tested for the presence of pyrrole substances with p-N,N-dimethylaminobenzaldehyde (DMAB, Ehrlich's reagent). Vibrissae and body hair were stained a reddish color that was distinctly different from that observed with the hair taken from control animals. Solubilized body hair protein from the treated animals gave a positive Ehrlich's test, while that from control animals was negative. Spectral analysis of the DMAB-treated hair from experimental animals disclosed a maximum absorbance at 530 nm, which indicated the presence of pyrrole substituents. Serial analysis of individual nose hairs taken during 2,5-HD administration showed a progression with time of the region staining positively for pyrroles, thus indicating that the process can proceed in growing hair. These findings suggest the potential utility of hair as an indicator for chronic exposure to this class of industrial chemicals possessing neurotoxicity potential. This could complement urinary analysis, which is now used to confirm recent exposure.