Treatment Outcome of MDR/RR TB in a Resource-Constrained Setup: A Four-Year Retrospective Analysis

Introduction

The emergence of drug resistance in TB treatment is a major public health threat. However, there are limited studies which are directed towards identifying factors that explain the gap in achieving treatment targets.

Objective

: This study aimed to assess the treatment outcome and its associated factors among patients with MDR/RR-TB in Dilchora Hospital Treatment Initiation Center from January 2014 to December 2018.

Method

: A retrospective cross-sectional study was conducted on patients with MDR/RR TB who initiated treatment between January 2014 and December 2018. Data were extracted from patient medical charts using a structured questionnaire. SPSS version 26 was used for analysis. Reports are presented using percentages and frequency. Independently associated factors for unfavorable outcome were identified using binary logistic regression model. Adjusted and crude odds ratio with 95% CI was used. P-value less than 0.05 was used to declare statistical significance.

Result

: A total of 146 patients were included in this study. The overall prevalence of unfavorable outcomes in this study for those with known outcomes was 8.6%. People living with HIV had a 6.47 times (95% CI: 1.14–36.68) increased odds of death as compared to those who are HIV negative. For every 1kg/m² increment in BMI, there was a 35.3% (AOR = 0.647; CI: 0.44–0.95) reduction in the odds of death as compared to those who had a 1kg/m2 lower BMI. Each additional month without culture conversion also increased the odds of death 2.24 times (95%CI: 1.08–4.66).

Conclusion & Recommendation

: The findings of our study showed an appreciably low poor treatment outcome for this outpatient program. HIV screening and early initiation of HAART, early identification and treatment of those who are underweight and a critical follow-up to the time of sputum culture conversion could help in further improving the outcomes.

Mortality and its predictors among patients treated for acute exacerbations of chronic obstructive respiratory diseases in Jimma Medical Center; Jimma, Ethiopia: Prospective observational study

Background

Chronic obstructive pulmonary disease (COPD) and asthma exacerbations are associated with ill health, increased mortality, and health care costs. However, there is limited evidence regarding mortality and its predictors among patients treated for COPD and asthma exacerbations in low-income nations, particularly in Ethiopia.

Methods

A-6 month prospective observational study was conducted from April 20-September 20, 2019. Data were collected on socio-demographic, baseline clinical characteristics and outcomes of asthma and COPD exacerbations. Data were entered into Epi-Data version 4.02.01 for cleaning and exported to STATA 14.0 for analysis. Kaplan-Meier (Log-rank test) was used to compare the baseline survival experience of the study participants and Cox proportional hazard regression analysis was conducted to determine the predictors of mortality. Adjusted hazard ratios (AHRs) with two-sided p-value <0.05 were considered statistically significant.

Results

A total of 130 patients (60% males) were included. The median (interquartile range (IQR)) age of the study participants was 59(50–70) years. The median (IQR) survival time to death was 17.5 (10–26) days. The total proportion of in-hospital mortality was 10.78% (14/130), and the incidence rate of mortality was 2.56 per 1000 person-years. The duration of oxygen therapy ≥16hours/day (AHR = 6.330, 95% CI [1.092–36.679], and old age (AHR = 1.066, 95% CI [1.0001–1.136] were the independent predictors of in-hospital mortality.

Conclusion

In this study, the in-hospital mortality rate was very high. Moreover, prolonged oxygen therapy (≥16hours/day) and old age were independently associated with in-hospital mortality. Therefore, special attention should be given to recipients of prolonged oxygen therapy and the elderly during hospital stay.

Disseminated Coccidioidomycosis in Africa

Background

Coccidioidomycosis is an endemic disease in the Americas. No cases have been reported in Africa.

Patient

A 23-year-old HIV seronegative Ugandan man was referred to Mulago National Referral Hospital in Kampala, Uganda with a 10-month history of haemoptysis and difficulty breathing, and a 6-month history of localized swellings on the extremities. He had associated weight loss and drenching sweats, but no fevers. He had taken anti-tuberculosis medicine for 2 months with no improvement. He had never travelled out of Uganda. On physical examination, he had cystic swellings and ulcerated lesions on the extremities. He had tachypnoea, crackles in the chest and mild hepatomegaly. Bronchoscopic examination showed two masses occluding the right main bronchus. Bronchoscopic biopsy showed findings consistent with coccidioidomycosis. The patient improved with antifungal treatment and was discharged.

Conclusion

We report the first case of disseminated coccidioidomycosis with pulmonary and cutaneous manifestations in Africa.

LEARNING POINTS

Predictors and short-term outcomes of recurrent pulmonary tuberculosis, Uganda: a cohort study

INTRODUCTION

Recurrent tuberculosis (TB) occurring >2 years after completing treatment for a prior TB episode is most often due to reinfection with a new strain of M. tuberculosis.

OBJECTIVES

We determined the prevalence and outcome of late recurrent TB among hospitalized patients in Kampala, Uganda.

METHODS

We conducted a retrospective analysis of patients admitted to Mulago Hospital who had cough of >2 weeks' duration and completed TB treatment >2 years prior to admission. All patients had mycobacterial culture performed on two sputum specimens and vital status ascertained 2-months post-enrollment. We performed modeling to identify predictors of recurrent TB and of survival.

RESULTS

Among 234 patients, 84 (36%) had recurrent TB. Independent predictors included younger age (aOR=0.64, 95% CI=0.42-0.97, p=0.04), chest pain >2 weeks (aOR=3.32, 95% CI=1.38-8.02, p=0.007), severe weight loss ≥5 kilograms (aOR=4.88, 95% CI=1.66-14.29, p=0.004) and presence of ≥1 WHO danger sign of severe illness (aOR=3.55, 95% CI=1.36-9.29, p=0.01). Two-month mortality was 17.8% (95% CI=10.5-29.2%), and was higher among patients not initiated on TB treatment (aHR=16.67, 95% CI=1.18-200, p=0.04), not on ART if HIV-positive (aHR=16.99, 95% CI=1.17-246.47, p=0.04) and with a history of smoking (aHR=1.20, 95% CI=1.03-1.40, p=0.02).

CONCLUSION

The high prevalence of late recurrent TB likely reflects high levels of TB transmission in Kampala. Increased use of empiric TB treatment and early ART treatment initiation if HIV-positive should be considered in patients with a prior history of TB, particularly if young, with weight loss ≥5kgs, chest pain >2 weeks or ≥1 WHO danger sign of severe illness.

Association of CXCL1 promoter polymorphism with ischaemic stroke in Korean population

This is a pilot study analysing association of chemokine gene polymorphisms (CXCL1, rs3117604; CXCL2, rs3806792; CCL2, rs2857656 and rs3760396; CCL5, rs2107538) in Korean patients with ischemic stroke (IS) (n = 120) and age-matched controls (n = 267). The CXCL1 gene and particularly T allele of rs3117604 was associated with IS.

Low prevalence of Pneumocystis pneumonia (PCP) but high prevalence of pneumocystis dihydropteroate synthase (dhps) gene mutations in HIV-infected persons in Uganda

Pneumocystis jirovecii pneumonia (PCP) is an important opportunistic infection in patients infected with HIV, but its burden is incompletely characterized in those areas of sub-Saharan Africa where HIV is prevalent. We explored the prevalence of both PCP in HIV-infected adults admitted with pneumonia to a tertiary-care hospital in Uganda and of putative P. jirovecii drug resistance by mutations in fungal dihydropteroate synthase (dhps) and dihydrofolate reductase (dhfr). In 129 consecutive patients with sputum smears negative for mycobacteria, 5 (3.9%) were diagnosed with PCP by microscopic examination of Giemsa-stained bronchoalveolar lavage fluid. Concordance was 100% between Giemsa stain and PCR (dhps and dhfr). PCP was more prevalent in patients newly-diagnosed with HIV (11.4%) than in patients with known HIV (1.1%; p = 0.007). Mortality at 2 months after discharge was 29% overall: 28% among PCP-negative patients, and 60% (3 of 5) among PCP-positive patients. In these 5 fungal isolates and an additional 8 from consecutive cases of PCP, all strains harbored mutant dhps haplotypes; all 13 isolates harbored the P57S mutation in dhps, and 3 (23%) also harbored the T55A mutation. No non-synonymous dhfr mutations were detected. PCP is an important cause of pneumonia in patients newly-diagnosed with HIV in Uganda, is associated with high mortality, and putative molecular evidence of drug resistance is prevalent. Given the reliability of field diagnosis in our cohort, future studies in sub-Saharan Africa can investigate the clinical impact of these genotypes.

Bronchoalveolar lavage enzyme-linked immunospot for diagnosis of smear-negative tuberculosis in HIV-infected patients

Background

Peripheral blood interferon-gamma release assays (IGRAs) have sub-optimal sensitivity and specificity for diagnosis of active pulmonary tuberculosis (TB). However, assessment of local immune responses has been reported to improve the accuracy of TB diagnosis.

Methods

We enrolled HIV-infected adults with cough ≥2 weeks’ duration admitted to Mulago Hospital in Kampala, Uganda and referred for bronchoscopy following two negative sputum acid-fast bacillus smears. We performed an ELISPOT-based IGRA (T-SPOT.TB®, Oxford Immunotec, Oxford, UK) using peripheral blood and bronchoalveolar lavage (BAL) fluid mononuclear cells, and determined the accuracy of IGRAs using mycobacterial culture results as a reference standard.

Results

94 HIV-infected patients with paired peripheral blood and BAL IGRA results were included. The study population was young (median age 34 years [IQR 28–40 years]) and had advanced HIV/AIDS (median CD4+ T-lymphocyte count 60 cells/µl [IQR 22–200 cells/µl]). The proportion of indeterminate IGRA results was higher in BAL fluid than in peripheral blood specimens (34% vs. 14%, difference 20%, 95% CI 7–33%, p = 0.002). BAL IGRA had moderate sensitivity (73%, 95% CI 50–89%) but poor specificity (48%, 95% CI 32–64%) for TB diagnosis. Sensitivity was similar (75%, 95% CI 57–89%) and specificity was higher (78%, 95% CI 63–88%) when IGRA was performed on peripheral blood.

Conclusions

BAL IGRA performed poorly for the diagnosis of smear-negative TB in a high HIV/TB burden setting. Further studies are needed to examine reasons for the large proportion of indeterminate results and low specificity of BAL IGRA for active TB in high HIV/TB burden settings.

Low prevalence of Pneumocystis jirovecii lung colonization in Ugandan HIV-infected patients hospitalized with non-Pneumocystis pneumonia

Pneumocystis jirovecii is an important opportunistic infection in human immunodeficiency virus (HIV)-infected patients. In the developed world, P. jirovecii epidemiology is marked by frequent colonization in immunosuppressed patients, but data on the prevalence of colonization are very limited in sub-Saharan Africa, where the majority of persons living with HIV reside. Our objective was to describe the epidemiology of P. jirovecii colonization among HIV-positive patients in a cross-sectional, hospital-based study of patients admitted with suspected pneumonia in Kampala, Uganda. P. jirovecii was detectable in bronchoalveolar lavage fluid from 7 (6%) of 124 consecutive patients with non-Pneumocystis pneumonia. Colonization was not associated with patient demographic or clinical information. This prevalence is substantially lower than in published studies in the developed world and suggests that there is a limited reservoir of organisms for clinical infections in this Ugandan population. These findings may partially explain the low incidence of Pneumocystis pneumonia in Uganda and other sub-Saharan African countries.

Clinical significance of normal chest radiographs among HIV-seropositive patients with suspected tuberculosis in Uganda

BACKGROUND AND OBJECTIVE

The frequency, aetiologies and outcomes of normal chest radiographs (CXRs) among HIV-seropositive patients with suspected pulmonary tuberculosis (TB) have been infrequently described.

METHODS

Consecutive HIV-seropositive adults hospitalized for cough of ≥2 weeks duration at Mulago Hospital (Kampala, Uganda), between September 2007 and July 2008, were enrolled. Baseline CXRs were obtained on admission. Patients with sputum smears that were negative for acid-fast bacilli (AFB) were referred for bronchoscopy with bronchoalveolar lavage (BAL). BAL fluid was examined for mycobacteria, Pneumocystis jirovecii and other fungi. Patients were followed for 2 months after enrolment.

RESULTS

Of the 334 patients, 54 (16%) had normal CXRs. These patients were younger (median age 30 vs 34 years, P = 0.002), had lower counts of CD4+ T lymphocytes (median 13 vs 57 cells/µL, P < 0.001), and were less likely to be smear positive for AFB (17% vs 39%, P = 0.002) than those with abnormal CXRs. Pulmonary TB was the most frequent diagnosis (44%) among those with normal CXRs, followed by unknown diagnoses, pulmonary aspergillosis and pulmonary cryptococcosis. The frequency of normal CXRs was 12% among pulmonary TB patients. There was a trend towards increased 2-month mortality among patients with normal CXRs compared to those with abnormal CXRs (40% vs 29%, P = 0.15).

CONCLUSIONS

Normal CXR findings were common among HIV-seropositive patients with suspected TB, especially those who were young, those with low CD4+ T cell counts and those with sputum smears that were negative for AFB. Mortality was high among those with normal CXRs. Normal CXR findings should not preclude further diagnostic evaluation in this population.

The role of speciation in positive Lowenstein-Jensen culture isolates from a high tuberculosis burden country

Objective

To determine the need for routine speciation of positive Lowenstein-Jensen mycobacterial cultures in HIV-infected patients suspected of having pulmonary tuberculosis at Mulago Hospital in Kampala, Uganda.

Methods

Sputum and bronchoalveolar lavage Lowenstein-Jensen mycobacterial culture isolates from consecutive, HIV-infected patients admitted to Mulago Hospital with 2 weeks or more of cough were subjected to IS6110 PCR and rpoB genetic analysis to determine the presence of Mycobacterium tuberculosis complex (MTBC) and non-tuberculous mycobacteria (NTM).

Results

Eighty (100%) mycobacterial cultures from 65 patients were confirmed to be members of MTBC. Subsequent analysis of the cultures from 54 patients by PCR and sequence analyses to identify co-infection with NTM confirmed the presence of MTBC as well as the presence of Micrococcus luteus (n = 4), Janibacter spp. (n = 1) and six cultures had organisms that could not be identified.

Conclusions

Presumptive diagnosis of tuberculosis on the basis of a positive Lowenstein-Jensen culture is sufficient in HIV-infected Ugandans suspected of having tuberculosis. Routine molecular confirmation of positive Lowenstein-Jensen cultures is unnecessary in this low resource setting.

Intranasal delivery of PEGylated salmon calcitonins: hypocalcemic effects in rats

To evaluate the hypocalcemic effect of polyethylene gtycol-conjugated salmon calcitonins (PEG-sCT) in rats, mono-PEGylated sCTs (mono-PEG-sCTs) and unmodified sCT were administered via the intranasal route and serum calcium levels were measured by colorimetric assay using o-cresolphthalein. Mono-PEG-sCTs were prepared with different sizes of succinimidyl succinate monomethoxy PEG molecules (PEG2K), PEG5K, PEG12K) and characterized by HPLC and MALDI-TOF mass spectrometry. Nasal instillation of mono-PEG2K-sCT at a dose of 2 IU/kg resulted in sustained reduction in serum calcium levels over 8 hr, with a maximum reduction (% maxd) of 13% after 6 hr of application. Whereas unmodified sCT showed a transient decrease in serum calcium levels with the maximum reduction (5%) observed after 30 min of administration. The overall reductions in serum calcium levels expressed as the net change in AUC relative to control in 8 hr were 11.9 +/- 0.2, 4.6 +/- 0.7, and 2.6 +/- 0.7% for mono-PEG2K-, mono-PEG5K-, and mono-PEG12K-sCT, respectively, compared to 3.2 +/- 0.6% for unmodified sCT. The relative bioavailability of nasally administered 2 IU/kg of mono-PEG2K-sCT was approximately 4-fold higher than nasally administrated unmodified sCT, and the absolute bioavailability was approximately 91% of intravenously injected sCT in 8 hr. It can be concluded that the intranasal absorption of mono-PEG-sCTs was inversely related to the molecular weights of the PEG attached. Of the PEGylated sCTs examined, mono-PEG2K-sCT showed the most pronounced hypocalcemic effect. Therefore the intranasal application would probably be an alternative route of administration for mono-PEG-sCTs in achieving sustained calcium-lowering effects.

Causes of lower respiratory infection in HIV-infected Ugandan adults who are sputum AFB smear-negative

SETTING

Mulago national referral and teaching hospital.

OBJECTIVE

To assess the etiology of lower respiratory infections in HIV-infected Ugandan adults who are sputum acid-fast bacilli (AFB) smear-negative.

DESIGN

A descriptive cross-sectional study. Participants included consecutive adult patients admitted to medical wards with respiratory symptoms of at least 3 weeks and infiltrates on chest radiograph. Those who were sputum AFB smear-negative and HIV-positive underwent bronchoscopy and bronchoalveolar lavage (BAL). BAL fluid was obtained and stained for AFB and Pneumocystis carinii, and cultured for bacteria and fungi.

RESULTS

Of 198 patients screened, 48 were sputum smear-positive for AFB. Sixty-seven were excluded for various reasons, leaving 83 patients who met the inclusion criteria and underwent bronchoscopy: 32 (38.6%) patients had P. carinii infection, 20 (24%) had pulmonary tuberculosis, nine (11%) had pulmonary Kaposi's sarcoma and pyogenic bacteria were identified in seven (8%). No aetiological diagnosis was found in 24 (30%) patients.

CONCLUSION

P. carinii and Mycobacterium tuberculosis were the commonest causes of disease among sputum AFB smear-negative, HIV-positive adults presenting to Mulago Hospital. Pulmonary Kaposi's sarcoma and pyogenic bacteria occurred with less frequency.

Bioavailability and mammary excretion of bisphenol a in Sprague-Dawley rats

This study reports the absolute oral bioavailability and mammary excretion of bisphenol A in rats. The oral bioavailability was determined after administration of relatively low iv (0.1 mg/kg) and oral (10 mg/kg) doses of bisphenol A to rats. After iv injection, serum levels of bisphenol A declined biexponentially, with the mean initial distribution and terminal elimination half-lives being 6.1 +/- 1.3 min and 52.5 +/- 2.4 min, respectively. The systemic clearance (Cls) and the steady-state volume of distribution (Vss) averaged 107.9 +/- 28.7 m/min/kg and 5.6 +/- 2.4 L/kg, respectively. Upon oral administration, the maximum serum concentration (Cmax) and the time to reach the maximum concentration (Tmax) were 14.7 +/- 10.9 ng/ml and 0.2 +/- 0.2 h, respectively. The apparent terminal elimination half-life of bisphenol A (21.3 +/- 7.4 h) after oral administration was significantly longer than that after iv injection, indicating the flip-flop of the absorption and elimination rates. The absolute oral bioavailability of bisphenol A was low (5.3 +/- 2.1%). To determine the extent of mammary excretion, bisphenol A was given by simultaneous iv bolus injection plus infusion to steady state at low, medium, and high doses. The steady-state serum levels of bisphenol A were linearly increased with higher dosing rates. The systemic clearance (mean range, 119.2-154.1 ml/min/kg) remained unaltered over the dosing rate studied. The levels of bisphenol A in milk exceeded those in serum, with the steady-state milk to serum concentration ratio being 2.4-2.7.

Potential estrogenic effects of bisphenol-A estimated by in vitro and in vivo combination assays

The potential estrogenic activities of bisphenol-A were investigated in vitro (E-screen and estrogen receptor competitive binding bioassays) and in vivo (uterotrophic assay). Uterotrophic responses were evaluated using mature ovariectomized Sprague-Dawley female rats treated subcutaneously with bisphenol A (1, 5, 10, 50, and 100 mg/kg/day), E2 (0.3 microgram/kg), and DES (0.3 microgram/kg) for 3 consecutive days. In a MCF-7 cell proliferation assay, E2 and DES used as positive estrogens induced maximum proliferation of MCF-7 cells at 1.0 nM, whereas BPA slightly induced MCF-7 cell proliferation at a higher level of 0.1 microM and maximum proliferation at 10 microM. In a competitive binding assay, E2 and DES showed inhibition of 17 beta-[3H]estradiol binding to the rat uterus ER with an IC50 of 1.0 nM and 0.5 nM, respectively. However, BPA had an IC50 of 5 microM, which was approximately 5,000 or 10,000-fold greater than the IC50 of E2 and DES. In uterotrophic assays, uterus (wet and blotted) and vagina weights were significantly increased at the dose of BPA 100 mg/kg/day in OVX Sprague-Dawley rats. These studies demonstrate that BPA exhibits weak estrogenic activity in all experimental systems, and thus its migration from epoxy resins or polycarbonate products should be controlled not to exceed a safety levels for humans.

Determination of growth hormone-releasing hexapeptide by reversed-phase high-performance liquid chromatography with electrochemical detection

A novel HPLC method with electrochemical detection is described for the determination of a growth-hormone-releasing hexapeptide (GHRP-6). HPLC conditions, such as the column, mobile phase, and oxidation potential, were optimized for sensitivity and selectivity of analysis. GHRP-6 was separated on a reversed-phase CN column with 37% acetonitrile in 100 mM phosphate buffer (pH 7.0) as the mobile phase. The optimum electrochemical oxidation signal was obtained at 0.85 V vs. Ag/AgCl in a glassy carbon working electrode due to two electroactive tryptophans and a histidine residue. Solid-phase extraction using octadecyl cartridges was optimized for sample cleanup of GHRP-6 from serum samples and the method was successfully applied over the concentration range of 5 to 100 ng/ml of analyte. reserved.

Identification of the modifying sites of mono-PEGylated salmon calcitonins by capillary electrophoresis and MALDI-TOF mass spectrometry

A capillary electrophoretic method (CE) was developed for the determination of the PEG-modification sites of three positional isomers of mono-PEG modified salmon calcitonins (mono-PEG-sCTs). Resistance to proteolytic degradation on the PEG modification sites resulted in different patterns of CE electropherograms for the tryptic digested mono-PEG-sCTs isomers, and the PEG modification sites were assigned accordingly. The PEG-modification sites were also confirmed directly by determining the molecular masses of the tryptic digested PEG-modified fragments of respective mono-PEG-sCT by the matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry.

Pharmacokinetic disposition of polyethylene glycol-modified salmon calcitonins in rats

This study first reports the pharmacokinetic disposition of polyethylene glycol (PEG)-modified salmon calcitonin (sCT) based on the number of attached PEG molecules. PEG-modified sCT was prepared by covalent linkage with succinimidyl carbonate monomethoxy polyethylene glycol. Mono- and di-PEG-sCTs were separated by size exclusion and reverse phase HPLC, and radioiodinated by the chloramine-T method with Na125I. 125I-mono-PEG sCT, 125I-di-PEG-sCT and unmodified 125I-sCT were administered to rats by i.v. injection. Serial blood samples, urine and various tissue samples were taken for the determination of radioactivity. Di-PEG-sCT exhibited significantly reduced systemic clearance (2.3 vs. 11.1 ml/min/kg) and steady-state volume of distribution (229.9 vs. 603.1 ml/kg), while mono-PEG-sCT showed a prolonged elimination half-life (189.1 min vs. 59.8 min) compared with unmodified sCT. The extent of urinary excretion of the PEG-modified sCTs was higher than for the unmodified sCT, but all these chemicals were excreted in urine in small quantities (< or = 0.6%). There was a tendency toward reduced accumulation of PEGylated sCTs in tissues, with its reduction being inversely proportional to the molecular size. Accumulation of the total radioactivity of the unmodified and PEG-modified sCTs was highest in the liver, followed by kidneys, lungs, spleen, heart and thyroid. When expressed per tissue gram weight, however, the highest radioactivity was found in the kidneys. PEGylated sCTs may have greater therapeutic potential via reduced systemic clearance and prolonged elimination half-life over unmodified sCT.

Pharmacokinetic disposition and tissue distribution of bisphenol A in rats after intravenous administration

This study examined the dose-linearity pharmacokinetics of bisphenol A, a U.S. Environmental Protection Agency (EPA) classified endocrine disruptor, in rats following iv administration. Upon iv injection of 0.2, 0.5, 1, or 2 mg/kg, serum levels of bisphenol A declined biexponentially, with mean initial distribution and elimination half-life ranges of 4-8.2 min and 38.6-62.2 min, respectively. There were no significant alterations in the systemic clearance rate (mean range 90.1-123.6 ml/min/kg) and the steady-state volume of distribution (mean range 4.6-6.0 L/kg) as a function of the administered dose. In addition, the area under the serum concentration-time curve linearly rose as the dose was increased. In a second study, bisphenol A was given by simultaneous iv bolus injection plus infusion to steady state, and levels were measured in serum and various organs. When expressed in concentration terms (e.g., amount accumulated per gram organ weight), bisphenol A was found predominantly in the lung, followed by kidneys, thyroid, stomach, heart, spleen, testes, liver, and brain. Ratios of the organ to serum bisphenol A concentrations exceeded unity for all the organs examined (ratio range 2.0-5.8) except for brain (ratio 0.75). Given the high systemic clearance and short elimination half-life, bisphenol A is unlikely to accumulate significantly in the rat.

The inhibition of ERK/MAPK not the activation of JNK/SAPK is primarily required to induce apoptosis in chronic myelogenous leukemic K562 cells

In this study, the downstream signaling of Bcr-Abl tyrosine kinase responsible for apoptosis resistance was investigated. DNA fragmentation, a hallmark of apoptosis, was observed after 2 days of herbimycin A treatment with a peak on 3 day. During the apoptosis induced by the treatment of herbimycin A, stress-activated protein kinase (SAPK) and p38 kinase were activated time- and dose-dependently, while extracellular signal-regulated kinase (ERK) was inhibited. However, apoptosis was induced by the treatment of PD98059, a specific inhibitor of MEK (MAPK or ERK kinase), not by the treatment of sorbitol, a strong activator of SAPK and p38 kinase. Although K562 cells were very resistant to sorbitol-induced apoptosis, DNA fragmentation was induced rapidly in Jurkat, HL-60 and U937 cells after exposure to sorbitol, despite that these apoptosis-sensitive cells have similar or lower activities of JNK/SAPK and p38 kinase compared with K562 cells after treatment of sorbitol. K562 cells had a much higher basal activity of ERK/MAPK than other apoptosis-sensitive cell lines, which were very susceptible to apoptosis induced by low dose of PD98059 compared with K562 cells. In HL-60 cells, sorbitol-induced apoptosis was prevented by the treatment of phorbol myristate 13-acetate (PMA), which activates the ERK/MAPK pathway, and this was blocked by PD98059. From these results, it could be suggested that the inhibition of ERK/MAPK not the activation of JNK/SAPK is primarily required to induce apoptosis in K562 cells.

Absorption, first-pass metabolism, and disposition of itraconazole in rats

This study examined the pharmacokinetic disposition, oral absorption and hepatic extraction of itraconazole and its active metabolite, hydroxyitraconazole, in rats. After i.v. injection, serum itraconazole concentrations decreased biexponentially, with an average terminal elimination half-life, volume of distribution and systemic clearance of 4.9 h, 6.0 l/kg and 14.2 ml/min/kg, respectively. When given orally, its absorption was low, with a mean absolute bioavailability of 16.6%. The metabolite to parent drug area under the curve (AUC) ratio was higher after oral administration compared with i.v. injection (mean ratio, 2.7 vs. 0.9). The hepatic drug extraction ratio determined after femoral and portal vein administration averaged 18.5%. When hydroxyitraconazole was injected i.v., the elimination half-life, volume of distribution and systemic clearance of itraconazole averaged 10.0 h, 2.4 l/kg and 3.4 ml/min/kg, respectively. The fraction of the systemically available itraconazole that was metabolized to hydroxyitraconazole was 21.0% and 76.0% after i.v. and oral administration, respectively. In summary, this study is the first reporting the hepatic extraction of itraconazole and the i.v. disposition characteristics of hydroxyitraconazole in rats. Itraconazole is a drug with a low hepatic extraction ratio and its systemic clearance appears to be largely accounted for by hepatic metabolism.

Downregulation of JNK/SAPK activity is associated with the cross-resistance to P-glycoprotein-unrelated drugs in multidrug-resistant FM3A/M cells overexpressing P-glycoprotein

In the present study, cross-drug resistance in multidrug-resistant (MDR) cells, which overexpress P-glycoprotein (Pgp), a mdr1 gene product, against Pgp-unrelated drugs, and its relevance to c-Jun N-terminal kinase (JNK)/stress-activated protein kinase (SAPK) activity were examined. The multidrug-resistant FM3A/M cells overexpressing Pgp were resistant to apoptotic cell death induced either by Pgp-related drugs including vincristine and vinblastine, which are pumped out by Pgp, or by the Pgp-unrelated drugs including 5'-fluorouracil (5-FU) and bleomycin, which are not targets for Pgp, compared with the parental FM3A cells. Verapamil reversed the resistance of FM3A/M cells to apoptosis induced by the Pgp-related drugs but not that induced by the Pgp-unrelated drugs. Interestingly, FM3A/M cells have shown significantly lower basal and drug-stimulated JNK/SAPK activities than FM3A cells. After transfection with pEBG-SEK or pEBG-SAPK constructs, FM3A/M cells recovered the basal and Pgp-unrelated drug-stimulated activities of JNK/SAPK and the susceptibility to Pgp-unrelated drug-induced apoptotic cell death comparable to those of FM3A cells. Furthermore, FM3A cells became resistant to apoptotic cell death induced by vincristine and 5-FU after transfection with pEBG-SEK(K --> R), a dominant negative inhibitory mutant of SEK. These results suggest that downregulation of JNK/SAPK activity appears to confer on Pgp-associated FM3A/M cells a cross-resistance to Pgp-unrelated drugs.

Bioavailability of itraconazole in rats and rabbits after administration of tablets containing solid dispersion particles

A tablet dosage form containing solid dispersions of itraconazole (Asd tablets) was prepared by using the spray-drying and wet granulation methods. The dissolution rate of itraconazole from Asd tablets was fast, with more than 90% released within 10 min, compared to less than 20% for a marketed product, Sporanox capsules. The oral absorption of itraconazole from Asd tablets was determined in rats and rabbits and was compared with that for Sporanox capsules. In the rat, there was no difference between the Asd tablets and Sporanox capsules in the mean area under the curve (AUC) (3089.5 +/- 4332.8 ng.hr/ml and 3653.9 +/- 2348.9 ng.hr/ml, respectively) and Cmax (295.0 +/- 344.5 and 390.5 +/- 169.4 ng/ml, respectively). Also, in the rabbit, no difference was found between the two products in the mean AUC (AUMC; 19357.9 +/- 5117.5 ng.hr/ml and 23382.2 +/- 6236.5 ng.hr/ml, respectively) and Cmax (766.4 +/- 276.5 and 1127.5 +/- 577.9 ng/ml, respectively). Despite the rapid in vitro release characteristics of itraconazole from the Asd tablets, the in vivo absorption of itraconazole was comparable to that of Sporanox capsules, with no difference in Tmax in both animal species. Serum levels of the major active metabolite hydroxyitraconazole were also measured. Itraconazole was rapidly converted to hydroxyitraconazole in both rats and rabbits, but there were species-specific differences in their pharmacokinetics. It is concluded that, in addition to drug solubility and dissolution characteristics, other formulation factors such as the physical state of the drug and the granulation process, may also need to be considered in the prediction of the in vivo absorption of itraconazole based on in vitro data.

Increased bioavailability of clomipramine after sublingual administration in rats

This study examined the absorption and disposition of clomipramine in rats after sublingual (5 and 50 mg/kg), oral (50 mg/kg), and iv (5 mg/kg) administration. The mean oral bioavailability of clomipramine was 24.8% and 29.7%, respectively, in conscious rats and in rats anesthetized with ketamine/xylazine (30/3 mg/kg). When given sublingually in isotonic saline at a dose of 50 mg/kg, clomipramine was rapidly absorbed, and the mean absolute bioavailability (36.2%) was increased over oral dosing. The mean AUC values of clomipramine were 2258 +/- 1762 ng.h/mL and 1891 +/- 867 ng.h/mL after oral administration to conscious and anesthetized rats, respectively, and 3303 +/- 1576 ng.h/mL after sublingual administration to anesthetized rats. Sublingual administration (5 mg/kg doses) of clomipramine formulated with a permeation enhancer, 2-hydroxypropyl beta-cyclodextrin, further increased the sublingual bioavailability to 57.1%. The sublingual route may be an alternative route of administration of clomipramine, providing enhanced bioavailability.

Enhanced solubility and dissolution rate of itraconazole by a solid dispersion technique

The aim of the present study was to improve the solubility and dissolution rate of a poorly water-soluble drug, itraconazole, by a solid dispersion technique. Solid dispersion particles of itraconazole were prepared with various pH-independent and -dependent hydrophilic polymers and were characterized by differential scanning calorimetry, powder X-ray diffraction and scanning electron microscopy. Of the polymers tested, pH-dependent hydrophilic polymers, AEA and Eudragit E 100, resulted in highest increases in drug solubility (range, 141.4-146.9-fold increases). The shape of the solid dispersion particles was spherical, with their internal diameter ranging from 1-10 microm. The dissolution rate of itraconazole from the tablets prepared by spray drying (SD-T) was fast, with > 90% released within 5 min.SD-T prepared with AEA or Eudragit E 100 at a 1:1 drug hydrophilic polymer ratio (w/w) showed approximately 70-fold increases in the dissolution rate over a marketed product.

Stability and cytotoxicity of Fab-ricin A immunotoxins prepared with water soluble long chain heterobifunctional crosslinking agents

The effects of the hindered and non-hindered water soluble long-chain disulfide bonds on the stability and cytotoxicity of the ricin A chain (RTA) immunotoxin were examined. The RTA immunotoxins were prepared with the Fab fragments of anti-common acute lymphoblastic leukemia antigen (CALLA) monoclonal antibody (Fab-RTA) using sulfosuccinimidyl-6-[(-methyl-(-(2-pyridyldithio)toluamido]hexanoate (S-LC-SMPT) and sulfosuccinimidyl-6-[3-(2-pyridyldithio)-propionamido]hexanoate (S-LC-SPDP). The prepared Fab-RTA immunotoxins were evaluated for their conjugation yield, immunoreactivity, thermal and disulfide bond stability and cytotoxicity. The conjugation yield of the Fab-RTA immunotoxin from the water soluble long chain crosslinking agents, S-LC-SMPT and S-LC-SPDP, were comparable. Both Fab-RTA immunotoxins exhibited a similar immunoreactivity and thermal stability in aqueous solution. However, S-LC-SMPT -mediated Fab-RTA, sterically hindered, showed an enhanced disulfide bond stability in vitro over S-LC-SPDP mediated one. In the cytotoxicity against antigenic cell Daudi, the S-LC-SMPT -mediated RTA immunotoxin maintained a comparable cytotoxicity, compared with S-LC-SPDP mediated Fab-RTA immunotoxin.

Isolation, characterization, and stability of positional isomers of mono-PEGylated salmon calcitonins

PURPOSE

To separate and characterize the different positional isomers of mono-PEGylated salmon calcitonins (mono-PEG-sCTs) and to evaluate the effects of the PEGylation site on the stability of different mono-PEG-sCTs in rat kidney homogenate.

METHODS

Mono-PEG-sCTs were prepared using succinimidyl carbonate monomethoxy polyethylene glycol (5,000 Da) and separated by gel-filtration HPLC followed by reversed-phase HPLC. To characterize PEGylated sCTs, matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) and reversed-phase HPLC of the trypsin digested samples were performed. Mono-PEG-sCTs and sCT in rat kidney homogenates were measured by column-switching reversed-phase HPLC with on-line detection of the radioiodinated samples using a flow-through radioisotope detector.

RESULTS

Three different mono-PEGylated sCTs were separated by reversed-phase gradient HPLC. From the MALDI-TOF MS analysis, the average molecular weight of mono-PEG-sCTs was confirmed as around 8650 Da. The presence of PEG moiety in the mono-PEG-sCTs was also manifested by the fact that the distance between two adjacent mass spectum lines was 44 Da which corresponds to PEG monomer unit. Tryptic digestion analysis demonstrated that these mono-PEG-sCTs are 3 positional isomers of N-terminus, Lys18- and Lys11-residue modified mono-PEGylated sCTs. The degradation half-life of these 3 positional isomers in rat kidney homogenates significantly increased in order of the N-terminus (125.5 min), Lys11- (157.3 min), and Lys18 residue modified mono-PEGylated sCT (281.5 min) over the native sCT (4.8 min).

CONCLUSION

Three positional isomers of mono-PEGylated sCTs were purified and characterized. Of these, the resistance to proteolytic degradation was highest for the Lys18-residue modified mono-PEG-sCT. These studies demonstrate that the in vivo stability of PEGylated sCTs is highly dependent on the site of PEG molecule attachment.

Expression of 1-aminocyclopropane-1-carboxylate oxidase during leaf ontogeny in white clover

We examined the expression of three distinct 1-aminocyclopropane-1-carboxylic acid oxidase genes during leaf ontogeny in white clover (Trifolium repens). Significant production of ethylene occurs at the apex, in newly initiated leaves, and in senescent leaf tissue. We used a combination of reverse transcriptase-polymerase chain reaction and 3'-rapid amplification of cDNA ends to identify three distinct DNA sequences designated TRACO1, TRACO2, and TRACO3, each with homology to 1-aminocyclopropane-1-carboxylic acid oxidase. Southern analysis confirmed that these sequences represent three distinct genes. Northern analysis revealed that TRACO1 is expressed specifically in the apex and TRACO2 is expressed in the apex and in developing and mature green leaves, with maximum expression in developing leaf tissue. The third gene, TRACO3, is expressed in senescent leaf tissue. Antibodies were raised to each gene product expressed in Escherichia coli, and western analysis showed that the TRACO1 antibody recognizes a protein of approximately 205 kD (as determined by gradient sodium dodecyl sulfate-polyacylamide gel electrophoresis) that is expressed preferentially in apical tissue. The TRACO2 antibody recognizes a protein of approximately 36.4 kD (as determined by gradient sodium dodecyl sulfate-polyacylamide gel electrophoresis) that is expressed in the apex and in developing and mature green leaves, with maximum expression in mature green tissue. No protein recognition by the TRACO3 antibody could be detected in senescent tissue or at any other stage of leaf development.

Preparation and characterization of polyethylene-glycol-modified salmon calcitonins

The conjugation of salmon calcitonin (sCT) by covalent linkage of polyethylene glycol (PEG) was attempted to overcome several disadvantages of sCT as a therapeutic drug, namely its rapid clearance from blood circulation and enzymatic degradation. The polymer employed was succinimidyl carbonate monomethoxypolyethylene glycol (12 kDa). Superose HR size-exclusion chromatography was applied to separate the PEGylated sCTs (mono-PEG-sCT and di-PEG-sCT) from the unmodified sCT. The PEGylation of sCT was verified by an electrophoresis gel stained with iodine and by MALDI-TOF mass spectrometry. The molecular weights of mono-PEG-sCT and di-PEG-sCT were determined to be 16,094 and 29,077 Da, respectively. PEGylated sCTs showed a substantially improved stability in rat liver homogenates as compared to the intact sCT, indicating that PEG molecules protected sCT from various degrading enzymes. These PEGylated sCTs exhibited similar biological activity to the intact sCT by adenosine cyclic 3',5'-phosphate (cAMP) assay. In clearance studies in the rat, PEGylated sCTs had significantly longer circulating half-lives than the intact sCT (11.2 min for mono-PEG-sCT and 54.0 min for di-PEG-sCT versus 4.7 min for intact sCT).

Rapid and sensitive determination of paclitaxel in mouse plasma by high-performance liquid chromatography

This report describes a rapid, simple and sensitive isocratic high-performance liquid chromatography with diode array UV detection for micro-sample analysis of paclitaxel in mouse plasma. The analysis utilized a Capcell-pak octadecyl analytical column and a mobile phase consisting of acetonitrile--0.1% phosphoric acid in deionized water (55:45, v/v). Paclitaxel and n-hexyl p-hydroxybenzoic acid (internal standard) were extracted from plasma by one-step extraction with tert.-butyl methyl ether. Peak purity was determined over a UV wavelength range of 200 to 400 nm. Paclitaxel and the internal standard were eluted at 3.4 min and 5.4 min, respectively, at a mobile phase flow-rate of 1.3 ml/min. No interfering peaks were observed and the total run time was 10 min. The standard curve was linear (r = 0.9999) over the concentration range of 0.010-500 micrograms/ml. The extraction recovery was > 90% for both paclitaxel and n-hexyl p-hydroxybenzoic acid. The intra- and inter-day assay variabilities of paclitaxel ranged from 0.4 to 2.2% and 0.6 to 7.8%, respectively. The LOD and LOQ were 5 and 10 ng/ml, respectively, for paclitaxel using a plasma sample volume of 100 microliters. This highly sensitive and simple assay method was successfully applied to a pharmacokinetic study after i.v. administration of paclitaxel 20 mg/kg to mice.

Stability of albuterol in continuous nebulization

Due to the emergent nature of situations requiring continuous nebulization of albuterol a premixed albuterol solution would provide faster access to the therapy when required. The purpose of this study was to evaluate the stability of albuterol solutions at a concentration (200 micrograms/mL) used in continuous nebulization when stored in various containers of polyvinyl chloride bags, polyolefin bags, polypropylene syringes and tubes and borosilicate glass tubes. Solutions were prepared in triplicate in 0.9% sodium chloride stored under refrigerated and room temperatures for seven days. Samples were removed and analyzed using a stability-indicating high-performance liquid chromatrography assay method. Albuterol was found to be stable (greater than 90% of the initial concentration remaining) for at least seven days in all five types of containers under the conditions tested.

Kinetic interaction between fluoxetine and imipramine as a function of elevated serum alpha-1-acid glycoprotein levels

The effect of elevated serum alpha-1-acid glycoprotein (AAG) levels on the pharmacokinetic interaction between imipramine and fluoxetine has been examined by utilizing a novel strain of transgenic mice which express serum AAG levels several times greater than normal. Before fluoxetine treatment, serum imipramine levels were approximately three times greater in transgenic mice than in control mice. Despite higher serum imipramine levels in transgenic mice, brain drug levels were lower than those found in control mice. Fluoxetine pre-treatment (20 mg kg(-1) for 5 days) resulted in an increase in serum imipramine levels in both groups of mice and the extent of the increase was greater in transgenic mice than in control mice (4.5-fold increase compared with 3.1-fold). Similarly, fluoxetine pre-treatment resulted in an increase in brain levels of imipramine in both groups of mice and the extent of the increase was greater in transgenic mice than in control mice (3.0-fold increase compared with 2.0-fold). Similar trends were observed for levels of desipramine in the serum and brain. Serum imipramine and desipramine levels did not correlate with their respective brain levels in the presence of elevated serum AAG levels before and after pre-treatment. These findings indicate that the extent of increases in imipramine and desipramine serum and brain levels are greater during elevated serum AAG states than during normal AAG states when imipramine is co-administered with fluoxetine.

Pharmacokinetics and antidepressant activity of fluoxetine in transgenic mice with elevated serum alpha-1-acid glycoprotein levels

Fluoxetine, a novel selective serotonin reuptake inhibitor utilized in the treatment of depression, is avidly bound to serum albumin and alpha-1-acid glycoprotein (AAG). AAG is an acute phase protein, and its serum levels are elevated in a variety of pathophysiological conditions including inflammation, depression, cancer, and acquired autoimmune deficiency syndrome. Further, the pharmacokinetic disposition and pharmacological activity of several highly bound drugs have been reported to be significantly altered as a result of elevated serum AAG. We investigated the effects of elevated serum AAG levels on the pharmacokinetic disposition, antidepressant activity, and steady state profile of fluoxetine and its demethylated metabolite, norfluoxetine. This was approached utilizing a novel strain of transgenic mice that expressed genetically elevated serum AAG levels severalfold over those of control mice. Serum and brain drug concentrations were determined by HPLC after fluoxetine administration. In transgenic mice, the volume of distribution and the terminal elimination half-life of fluoxetine were significantly reduced. Further, significant reductions in brain-to-serum fluoxetine concentration ratios and antidepressant activity were observed in transgenic mice, despite having higher serum drug levels than control mice. This trend in the serum continued at steady state, and brain fluoxetine levels were significantly lower in transgenic mice. The results of this study provide valuable insights regarding the consequences of elevated serum AAG levels, often seen in several disease states, on the pharmacokinetic disposition of fluoxetine.

Quantification of fluoxetine and norfluoxetine serum levels by reversed-phase high-performance liquid chromatography with ultraviolet detection

A rapid and sensitive high-performance liquid chromatography assay method was developed to determine serum fluoxetine and norfluoxetine levels by single extraction of 0.1 ml of serum with sodium hydroxide. The mobile phase (55% acetonitrile-45% distilled water containing 10 mM aqueous triethylamine) was used to separate fluoxetine and norfluoxetine (25-1000 ng/ml, using clomipramine as the internal standard) by ultraviolet detection at 226 nm. The inter- and intra-day variabilities of fluoxetine and norfluoxetine were 13-18%, and the recoveries of both drugs exceeded 89%. This assay method was applied to a pharmacokinetic disposition study of fluoxetine in mice.

Mandrake toxicity. A case of mistaken identity

A 31-year-old man ingested an unknown amount of mandrake plant purchased at a local health food store and came to the emergency department with severe nausea and vomiting. He was hospitalized overnight but recovered uneventfully without obvious adverse systemic effects. This plant was almost certainly Podophyllum peltatum based on chromatographic identification of podophyllotoxin in a sample. However, the patient had mistakenly believed he was taking the anticholinergic and hallucinatory plant Mandragora officinarum, which is also known as mandrake. Other users of herbal substances and authors of the medical literature have also confused these 2 versions of mandrake. Given the growing popularity of alternative therapies, physicians should understand the distinction between these substances and should be aware of the medical effects of other commonly used herbal remedies.

In vitro evaluation of a series of N-dodecanoyl-L-amino acid methyl esters as dermal penetration enhancers

A series of N-dodecanoyl-L-amino acid methyl esters (1-10) and n-pentyl N-acetylprolinate (11) were evaluated for dermal enhancement properties using an in vitro diffusion cell technique. Methods of synthesis of these compounds were described. Enhancers were applied 1 h prior to drug treatment. Hydrocortisone was used as the model drug and was applied to excised hairless mouse skin as a saturated suspension in propylene glycol. Enhancement ratios (ER) were determined for permeability coefficient, 24 h diffusion cell receptor concentration (Q24), and 24 h full-thickness skin steroid content. Controls received no enhancer pretreatment of the skin. N-Dodecanoyl-L-proline (10) showed the highest Q24 value for total steroid (ER 13.7) while N-dodecanoyl-L-phenylalanine (5) showed the highest total steroid skin retention (ER 16.5).

Steady-state kinetics of imipramine in transgenic mice with elevated serum AAG levels

PURPOSE

The effect of elevated serum alpha-1-acid glycoprotein (AAG) concentrations on the steady-state serum and brain levels of imipramine and its metabolite desipramine was assessed. This was approached using a novel strain of transgenic mice whose basal endogenous serum AAG levels were 8.6-fold elevated over normal.

METHODS

Imipramine was administered by s.c. infusion or i.p., injection into transgenic and control mice. After drug administration, serum and whole brain were harvested and analyzed for imipramine and desipramine concentrations. Equilibrium dialysis was performed to determine the extent of imipramine protein binding in transgenic and control sera. Serum and brain samples were analyzed for imipramine and desipramine content by an established HPLC method with UV detection.

RESULTS

At steady-state, the mean serum imipramine concentration was significantly higher in transgenic mice than in control mice (859.0 vs. 319.9 ng/ml). In contrast, the mean steady-state brain imipramine concentration was significantly lower in transgenic mice (3,862.6 vs. 7,307.7 ng/g). Similarly, in transgenic mice, the mean steady-state serum desipramine concentration was significantly higher (176.7 vs. 39.0 ng/ml) while the mean brain desipramine concentration was lower (243.0 vs. 393.5 ng/g). The serum unbound fraction of imipramine was 3-fold lower in transgenic mice (0.03 vs. 0.09).

CONCLUSIONS

Elevated serum AAG impedes the transport of imipramine and desipramine into the brain. Further, in the presence of elevated serum AAG levels, imipramine and desipramine concentrations in the brain did not correlate with their respective concentrations in the serum.

Altered disposition and antidepressant activity of imipramine in transgenic mice with elevated alpha-1-acid glycoprotein

Imipramine is a tricyclic antidepressant known to be bound in the serum primarily by alpha-1-acid glycoprotein. The present study examined the effect of changes in serum alpha-1-acid glycoprotein levels on the pharmacokinetics and antidepressant activity of the drug by utilizing a novel set of transgenic mice in which the steady-state level of alpha-1-acid glycoprotein is significantly elevated over normal. The pharmacokinetic disposition was characterized after i.v. and i.p. injections in transgenic and control mice. In transgenic mice, there were significant decreases in the serum unbound fraction (0.62+/- 0.38 vs.2.48 +/- 0.43%), Vd (9.0 +/- 2.5 vs. 22.4 +/- 3.2 liters/kg), T1/2 (35.0 +/- 7.6 vs. 65.3 +/- 7.6 min) and fraction of dose excreted unchanged in urine (0.14 +/- 0.07 vs. 0.70 +/- 0.20%) with no significant alterations in systemic clearance (204.7 +/- 56.1 vs. 292.8 +/- 58.4 ml/min/kg) compared to control values. The antidepressant activity of imipramine was measured by a swimming-immobility test 30 min after either imipramine (30 mg/kg i.p.) or saline treatment. After saline treatment, there were no significant differences in the duration of swimming despair between transgenic (183 +/- 24 sec) and control (175 +/- 12 sec) mice. Imipramine treatment resulted in reductions in the duration of immobility in both transgenic (130 +/- 21 sec) and control (54 +/- 33 sec) mice. The extent of reduction was significantly less in transgenic animals than in control animals. These alterations in the antidepressant action appeared to correlate with the unbound drug concentration but not with the total drug concentration.

Rapid microsample analysis of imipramine and desipramine by reversed-phase high-performance liquid chromatography with ultraviolet detection

A rapid and highly sensitive HPLC assay method was developed to measure small amounts of imipramine and its major metabolite, desipramine. The assay involved simple extraction procedures using clomipramine as the internal standard. The mobile phase consisted of acetonitrile (60%) and 0.01 M triethylamine in distilled water (40%) with the pH adjusted to 3.0. Separations were achieved on a C18 column and the effluent measured for UV absorption at 260 nm. The chromatographic separation was excellent, with no interference from endogenous serum constituents. This assay was suitable for measuring drug concentrations in the range of 10-1000 ng/ml using a 0.1-ml serum sample. The method was applied to a drug disposition study in transgenic mice with increased plasma alpha 1-acid glycoprotein.

Mammary excretion of cannabidiol in rabbits after intravenous administration

The present study examined the distribution of cannabidiol into milk after an intravenous bolus injection (3 mg kg-1) to lactating rabbits. Drug concentrations in milk and serum were measured by HPLC. Cannabidiol was excreted into milk rapidly and the drug levels in milk increased over a 4-24-h period following the maternal injection. The mean milk to serum concentration ratio was 25.9, indicating a significant accumulation of the drug in milk.

Transplacental and nonplacental clearances of diphenhydramine in the chronically instrumented pregnant sheep

Pharmacokinetic studies of the histamine H1-receptor antagonist diphenhydramine were conducted in eight chronically instrumented pregnant sheep at 126-138 days of gestation. Diphenhydramine was administered by simultaneous intravenous bolus injection and infusion to steady state given 48 h apart, to the ewe and the fetus on separate occasions. Average steady-state drug concentration in plasma after maternal infusion was 212.1 +/- 67.8 ng/mL in the mother and 36.3 +/- 14.4 ng/mL in the fetus, resulting in a fetal-to-maternal concentration ratio of 0.19 +/- 0.10. Following fetal infusions, maternal and fetal steady-state drug concentrations were 31.1 +/- 11.6 and 447.6 +/- 185.2 ng/mL, respectively. The free fraction of diphenhydramine determined in the fetus (0.277 +/- 0.087) was significantly greater than that in the mother (0.141 +/- 0.079). Transplacental and nonplacental clearances were calculated at steady state according to a general two-compartment open model, with drug elimination occurring from both compartments. The total fetal clearance (472.7 +/- 215.7 mL/min) was relatively small compared with the total maternal clearance (3426.1 +/- 905.8 mL/min). The transplacental clearance from fetus to mother (264.4 +/- 138.7 mL/min) was approximately threefold higher than that from mother to fetus (82.4 +/- 40.5 mL/min). Maternal nonplacental clearance (3343.8 +/- 890.7 mL/min) accounted for 97.8 +/- 1.1% of the maternal total clearance, whereas fetal nonplacental clearance (208.4 +/- 80.4 mL/min) accounted for 45.1 +/- 4.7% of the fetal total clearance. It is concluded that in the fetus both the transplacental and nonplacental pathways are important for drug elimination.

Sustained bronchodilation with isoproterenol poly(glycolide-co-lactide) microspheres

An animal study was carried out to evaluate the in vivo bronchodilator action of isoproterenol (Iso) from poly(glycolide-co-lactide) (PGL) microspheres. Microspheres with a mean diameter of 4.5 microns and a drug load of 7% were administered intratracheally to Long-Evans rats. The microspheres released about 70% of the incorporated drug in the instillation medium before administration, which provided immediate action, and the remaining 30% was available for sustained release. A total of 120 animals was anesthetized, paralyzed, artificially ventilated, and divided into 15 groups (n = 8): 3 groups each for saline, blank microspheres, free Iso, blank microspheres with free Iso, and microencapsulated Iso. All instillations were made in a volume of 1 ml/kg and the dose of all Iso preparations was 0.1 mg/kg. At 3, 6, or 12 hr after the intratracheal instillation, a serotonin challenge (40 micrograms/rat) was administered intravenously to constrict the airways. Airway function tests were performed at each time interval on one group of animals by a maximal expiratory flow-volume maneuver. The heart rate in animals receiving Iso formulations was similar to that in the saline control group, indicating minimal systemic effect of the dose administered. The systemic serum levels were below 2 ng/ml in all the groups. Animals receiving encapsulated Iso resisted the serotonin challenge for at least 12 hr after intratracheal instillation, indicating that the drug was still present over this period of time. On the other hand, the serotonin-induced airway constriction observed in the animals receiving blank microspheres, free Iso, or free Iso with blank microspheres was similar to that in saline controls at all time points. The results clearly show that only a small fraction of the free dose is required in sustained-release form for a prolonged pharmacological effect, resulting in a 50- to 100-fold reduction in the total dose administered.

Pharmacokinetics of cimetidine during lactation: species differences in cimetidine transport into rat and rabbit milk

The disposition of cimetidine, including transfer into milk, was characterized in the rabbits and rats. Nursing rabbits and suckling offspring exhibited similar pharmacokinetics with a mean systemic disease (CL) in the adults and pups of 22.0 +/- 5.2 and 30.4 +/- 8.9 ml/min/kg, respectively. Cimetidine exhibited a distributional time lag and a prolonged T 1/2 in milk compared to serum (70 +/- 15 vs. 33 +/- 5 min), resulting in a time-dependent milk to serum (M/S) drug concentration ratio. The ratio of the area under the time curve of cimetidine in serum and milk was 1.49 +/- 0.37 and was comparable to a diffusional model predicted M/S ratio of 1.16 +/- 0.11. Unbound CL after a high cimetidine infusion regimen (16.6 +/- 7.3 ml/min/kg) was significantly less than that after two lower infusion rates (26.2 +/- 4.9 and 29.4 +/- 12.3 ml/min/kg, respectively). M/S determined at increasing steady-state serum concentrations were 1.03, 1.08 and 1.08, respectively, which agreed well with the corresponding predicted M/S (1.06, 1.14 and 1.13, respectively). Cimetidine was also administered to lactating rats and resulted in a concentration-dependent decrease in CL (11.2 +/- 1.5, 10.8 +/- 2.7 and 7.30 +/- 1.0 ml/min, respectively) after three increasing infusion rates. The steady-state M/S ratio decreased slightly from 31.9 +/- 9.0 to 26.5 +/- 9.5 and 24.6 +/- 6.4 with the increasing infusion rate. Steady-state M/S values were 6-fold higher than the predicted M/S value (4.19). Hence, cimetidine transport into rabbit milk appears to be governed by diffusion, whereas cimetidine transfer into rat milk may involve active transport.

Pharmacokinetics of caffeine and its demethylated metabolites in lactating adult rabbits and neonatal offspring. Predictions of breast milk to serum concentration ratios

The purpose of this study was to assess the pharmacokinetics of caffeine and its metabolites in the lactating rabbit and suckling pup. The ability of a diffusional model to predict milk-to-serum drug concentration ratios (M/S) observed in vivo from in vitro experiments was established. The distribution into milk of caffeine, paraxanthine, theobromine, and theophylline was measured in lactating New Zealand White rabbits following an iv bolus dose of caffeine (5 mg/kg). M/S ratios were determined in vivo (M/Sobs; caffeine = 0.875 +/- 0.052; paraxanthine = 0.358 +/- 0.019; theobromine = 0.829 +/- 0.038; and theophylline = 0.412 +/- 0.054) under single dose conditions using area under the milk and serum concentration-time profiles. Predicted M/S values (M/Spred; caffeine = 0.797 +/- 0.040; paraxanthine = 0.316 +/- 0.029; theobromine = 0.692 +/- 0.062; and theophylline = 0.385 +/- 0.039) were calculated from in vitro measurements of the unbound fractions of drug in skim milk and serum (fm and fs, respectively), the skim-to-whole milk drug concentration ratio (S/W), milk and serum pH, and the pKa of the model compound. The pharmacokinetic profile of caffeine in the suckling pup following iv bolus administration (5 mg/kg) was more prolonged compared with adult rabbits. The mean systemic clearance of total caffeine (CIs) in the adults and the pups was 3.83 +/- 1.94 and 1.14 +/- 0.80 ml/min/kg, respectively. The mean unbound systemic clearance (CIs,u) for caffeine was 5.09 +/- 2.60 ml/min/kg in the adults and 1.41 +/- 0.71 ml/min/kg in the pups.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of acetaminophen, antipyrine, and salicylic acid in the lactating and nursing rabbit, with model predictions of milk to serum concentration ratios and neonatal dose

The rabbit was utilized for examining the pharmacokinetics of three compounds (acetaminophen, AC; antipyrine, AN; and salicylic acid, SA) in nursing adults and their suckling offspring and for assessing the ability of a diffusional model to predict milk to serum drug concentration ratios (M/S) from in vitro experiments. AC, AN, and SA serum concentration time profiles declined monoexponentially for both adults and their pups. The mean systemic clearance (Cls) for AC in the adults and pups was 16.1 and 13.7 ml/min/kg, respectively. The mean half-lives of AC (t1/2) were 25.5 and 33.3 min in the adult and pup groups, respectively. AN declined in parallel for adult rabbits and an older group of suckling pups (23-25 days old). In a younger group of pups (18-21 days old) it declined with a longer t1/2 (97.5, 95.1, and 347.6 min in the adults, older pups, and younger pups, respectively). The mean AN Cls in the adults, the older pups, and the younger pups was 5.34, 6.30, and 1.91 ml/min/kg, respectively. The time course of SA was prolonged in the suckling pups (t1/2 of 633 min in the pups vs 78.7 min in the adult). The mean Cls values in the adults and the pups were 1.05 and 0.27 ml/min/kg, respectively. The mean systemic clearance of unbound drug (Clu) for SA was 11.2 ml/min/kg in the adults and 0.92 ml/min/kg in the pups. The serum protein binding of AC and AN was limited, whereas the mean free fraction for SA was 9.7% in adult serum and 32.5% in pup serum. AC and AN in milk paralleled serum drug profiles; a time lag was noted for milk SA. M/S ratios were determined in vivo (M/Sobs; AN = 0.885, AC = 0.580, and SA = 0.125) using area under the milk and serum concentration time profiles. Predicted M/S values (M/Spred; AN = 0.779, AC = 0.578, and SA = 0.085) were calculated from in vitro measurements of the unbound fractions of drug in skim milk and serum, the skim to whole milk drug concentration ratio, milk and serum pH, and the pKa of the model compound. Mean values for M/Sobs were highly correlated with M/Spred values (r2 = 0.976) when the present data were combined with previous data for propranolol, phenobarbital, phenytoin, and diazepam (Fleishaker, J.C., and McNamara, P.J., J. Pharmacol. Exp. Ther. 244, 919, 1988). These results support the usefulness of the diffusional model for predicting M/S in vivo, provided that the distributional process is governed by passive diffusion.(ABSTRACT TRUNCATED AT 400 WORDS)

Pharmacokinetics of diphenhydramine after dose ranging in nonpregnant ewes

Studies were conducted to characterize the pharmacokinetics of diphenhydramine in nonpregnant ewes after iv administration of 25-, 50-, 100-, and 200-mg doses of diphenhydramine hydrochloride on a crossover basis. Plasma drug concentration versus time data exhibited multiexponential characteristics. The initial distribution half-life increased from 5 to 9 min and the elimination half-life from 34 to 68 min as the dose was increased. There was also an increase in the volume of distribution (from 3 to 6 L/kg) with increasing dose. The elimination half-life and the volume of distribution after a 200-mg dose were significantly greater than after a 25-mg dose. There was, however, a linear increase in AUC0 infinity as dose was increased. The average total body clearance (approximately 5 L/h/kg) remained unchanged regardless of dose. The free fraction of diphenhydramine determined by equilibrium dialysis averaged 0.229 +/- 0.080, and the extent of drug binding to plasma protein was independent of the drug concentrations encountered (30-780 ng/mL) in the nonpregnant sheep in vivo. Concentration-independent binding of the drug was also confirmed by in vitro binding studies over the drug concentration range 10-2000 ng/mL. Therefore, it appears that changes in the volume of distribution are likely to be a result of changes in tissue uptake or binding of the drug as a function of dose.

Effects of diphenhydramine in the fetal lamb after maternal or fetal administration

The effects of diphenhydramine on fetal behavioral states, breathing activity, blood gas status, arterial pressure and heart rate have been investigated in the fetal lamb after maternal or fetal drug administration to steady state in chronically instrumented pregnant sheep. During maternal drug infusion there were declines in the percentage of low voltage electrocorticographic (ECoG) pattern 55-46%), the percentage of low voltage ECoG activity containing rapid eye movements (80-55%), the overall incidence of fetal breathing (42-21%) and in the amount of breathing during low voltage ECoG activity (67-36%). These sedative like effects occurred at fetal plasma drug concentrations (approximately 36 ng/ml) lower than those resulting in discernable central nervous system effects in adults. Drug infusion to fetus achieved higher fetal plasma drug levels (approximately 448 ng/ml) and resulted in a transient decline in arterial Po2 and pH, associated with transient tachycardia and vigorous breathing movements during the initial portion of the infusion. There was also a significant fall in the amount of low voltage ECoG pattern (51-26%) and marked increases in the amount of intermediate voltage pattern (8-46%), and an increase in the occurrence of rapid eye movements during this intermediate voltage pattern (8-63%). In summary, diphenhydramine elicits significant effects in the fetal lamb, the precise nature of which varies with drug concentration.

Drug accumulation in lung fluid of the fetal lamb after maternal or fetal administration

The pharmacokinetic characteristics of the antiemetic drug metoclopramide and the antihistamine diphenhydramine have been determined in a chronically catheterized pregnant sheep preparation. Metoclopramide and diphenhydramine were administered by separate maternal and fetal intravenous infusions to a steady state as well as by maternal intravenous bolus dosing. Drug concentrations in the maternal and fetal plasma and the amniotic and tracheal fluids were measured by means of capillary gas-liquid chromatographic assay techniques. Both metoclopramide and diphenhydramine were excreted into tracheal fluid in substantial quantities. Tracheal metoclopramide concentrations were found to exceed fetal plasma levels by about fifteen-fold while diphenhydramine attained maximal excretion in tracheal fluid of about five times that seen in fetal plasma. Drug levels were observed to accumulate slowly in amniotic fluid and eventually to exceed tracheal concentrations. The markedly elevated concentrations of these drugs in fetal lung fluid suggests that the fetal lung may be an important route of drug distribution, elimination, and excretion.