Adenocarcinoma of the rat esophagus in the presence of a proton pump inhibitor: a pilot study

This study examines the effects of a proton pump inhibitor on a rat model of duodenogastric reflux. Duodenoesophageal reflux was induced in 60 rats by performing a duodenesophagostomy. The study group received daily intraperitoneal injections of a proton pump inhibitor for 6 months and the control group received an equivalent injection of saline. Rats were examined at death for macroscopic tumor, dysplasia, adenocystic changes, papillomatosis, and adenocarcinoma. Five out of 19 rats in the study group and three out of 20 rats in the control group developed dysplastic/adenocarcinomatous changes. Ten of the rats in the study group died before the end of the study, as opposed to one in the control group (this is not statistically significant). There was no difference in the number of cancers that developed in the two groups. However, there was an insignificant trend to earlier appearance of detectable disease in the study group.

Loss of purinergic P2X(3) and P2X(5) receptor innervation in human detrusor from adults with urge incontinence

Activation of purinergic P2X receptors associated with the parasympathetic nerves that supply the human bladder smooth muscle (detrusor) is implicated in control of detrusor contractility. The relative abundance of all seven subtypes colocalized with synaptic vesicles on parasympathetic nerves was examined in specimens from normal adult bladder, infants, and in adults with overactive detrusor contractility and a diagnosis of idiopathic detrusor instability (IDI) to determine whether receptor distribution varied with age or in patients with incontinence. Alteration in control of detrusor innervation was examined with P2X subtype-specific antibodies and an antibody against synaptic vesicles, using immunofluorescence and confocal microscopy. Detrusor samples were taken from: controls, at cystectomy for cancer or cystoscopic biopsy for hematuria (n = 22; age 33-88), child bladder, at surgical correction of vesico-ureteric reflux (n = 21; age 4 months to 2 years), and adults with detrusor instability at cystoscopy-cystodistension (n = 18; age 30-81). Adult specimens contained muscle with large varicosities (1.2 microm) along parasympathetic nerves with colocalized patches of all P2X(1-7) subtypes. Infant bladder revealed little evidence of P2X at age <9 months but approached adult levels at 2 years. Detrusor from IDI patients revealed selective absence of P2X(3) and P2X(5) beneath all the varicosities. This specific lack of P2X(3) and P2X(5) may impair control of detrusor contractility and contribute to the pathophysiology of urge incontinence.

Pharmacokinetics of zidovudine and lamivudine in neonates following coadministration of oral doses every 12 hours

A phase I, repeat-dose, open-label study was conducted to determine the pharmacokinetics and safety of zidovudine and lamivudine, coadministered orally every 12 hours, in 16 neonates whose mothers were infected with human immunodeficiency virus type 1 (HIV-1). The prospective mothers had been stabilized on a zidovudine/lamivudine regimen since week 36 of pregnancy to prevent mother-to-child transmission of HIV. During 1 week postpartum, the mothers received zidovudine 300 mg plus lamivudine 150 mg every 12 hours and breastfed. Neonatal treatment was initiated 12 hours following birth with 4 mg/kg of zidovudine suspension plus 2 mg/kg of lamivudine solution every 12 hours; this regimen was continued for 1 week. Between days 1 and 7 of neonatal treatment, the neonatal oral clearance (CL/F) of zidovudine and lamivudine increased by 2-fold (p < 0.001) and 1.6-fold (p = 0.004), respectively, possibly reflecting maturation of intestinal hepatic and renal function occurring during the first week of life. Day 7/day 1 ratios for exposure (area under the serum concentration-time curve [AUC]) and maximum observed serum concentration (Cmax) were 0.48 and 0.63, respectively, for zidovudine and 0.64 and 0.73, respectively, for lamivudine. At the time of delivery, the geometric mean cord/maternal concentration ratio was 1.24 for zidovudine and 1.12 for lamivudine, indicating free passage of each drug across the placenta. The maternal and neonatal treatment regimens were well tolerated. The results of this study confirm that in the neonate, a convenient regimen combining zidovudine 4 mg/kg and lamivudine 2 mg/kg, administered orally every 12 hours, provides zidovudine serum exposure very similar to that reported with the standard neonatal zidovudine regimen of 2 mg/kg every 6 hours, as well as lamivudine serum exposure within the range reported in adults receiving lamivudine 150 mg twice a day and children receiving 4 mg/kg twice a day.

Thymoma: trends over time

BACKGROUND

This is a review of a series of patients who presented with thymoma over the most recent 20-year period. Changes and trends in disease patterns were documented.

METHODS

Data were collated retrospectively but all pathology slides were reviewed. Survival functions were estimated using the Kaplan-Meier method.

RESULTS

Seventy-one patients had a partial or total thymectomy during this period for a thymoma. Average age was 55 years. Twenty-three patients (32%) had myaesthenia gravis. Eighteen patients (25%) were asymptomatic. Thirty-three patients (47%) had stage 1 disease. Complete resection was achieved in 60 patients (85%). Five-year survival was 88%. Fifty percent of patients with myesthenia gravis showed improvement in symptoms.

CONCLUSIONS

Five- and 10-year survival rates in this study are better than in other series. We attribute this to an increasing number of patients with stage 1 and stage 2 disease, particularly those with myasthenia gravis who now have screening computer tomography, and also to the surgical intent of aiming to achieve complete resection even if excision of adjacent tissue is required.

GW420867X administered to HIV-1-infected patients alone and in combination with lamivudine and zidovudine

PURPOSE

GW420867X is a nonnucleoside inhibitor of HIV-1 reverse transcriptase. The primary objective was to assess the safety of GW420867X in HIV-1-infected patients. The secondary objectives were to assess the effect of GW420867X on plasma HIV-1 RNA and viral genotype and phenotype and to examine the pharmacokinetics of GW420867X in HIV-1-infected patients.

METHOD

HIV-1-infected patients were randomized to GW420867X 50 mg/day, 100 mg/day, or 200 mg/day from days 1-28 (n = 15 per group). Lamivudine (3TC) plus zidovudine (ZDV) was added from days 8-28. A control group (n = 15) received GW420867X, 3TC, and ZDV placebos.

RESULTS

Plasma HIV-1 RNA and CD4+ counts improved in the GW420867X groups at days 8 and 28. No significant development of drug resistance was detected. Median observed peak GW420867X concentration (C(max)) generally occurred at 2 hours. The area under the curve over the dosing interval (AUCtau)on day 14 increased less than proportionally to dose, suggesting there was increased clearance and/or decreased absorption. Mean trough GW420867X concentrations were many fold above the in vitro IC(50) in the presence of human serum proteins. Seven of 15 patients on 50 mg GW420867X, 8/15 on 100 mg GW420867X, 12/15 on 200 mg GW420867X, and 8/15 on placebo reported drug-related adverse events.

CONCLUSION

GW420867X was well tolerated and has potent antiretroviral activity alone and in combination with 3TC plus ZDV.

Metabolic disposition and pharmacokinetics of [14C]-amprenavir, a human immunodeficiency virus type 1 (HIV-1) protease inhibitor, administered as a single oral dose to healthy male subjects

The objective of this study was to determine the metabolic profile, routes of elimination, and total recovery of amprenavir and its metabolites after a single oral dose of [14C]-amprenavir. Six healthy male subjects each received a single oral 630 mg dose of amprenavir containing 95.76 microCi of [14C]-amprenavir in this Phase I mass balance study. The metabolic disposition of amprenavir was determined through analyses of radiocarbon in whole blood, plasma, urine, and stool samples, collected for a period of 10 to 17 days postdosing. Cerebral spinal fluid (CSF) sampling was conducted on day 1. The ratio of unchanged amprenavir AUC0-->infinity to plasma radiocarbon was 27%, suggesting that most of the radiocarbon was metabolites. The median total recovery of the administered dose of radiocarbon was 89% (range: 66%-93%), with 75% (range: 56%-80%) recovered in the feces and 14% (range: 10%-17%) in the urine. Most of the recovered radiocarbon in the feces and urine was excreted within 240 and 48 hours postdose, respectively. Of the 75% of the radiocarbon dose recovered in the feces, 62% was identified as a metabolite resulting from dioxidation of the tetrahydrofuran ring (GW549445X) and 32% as a metabolite resulting from subsequent oxidation of the p-aniline sulfonate group (GW549444X). Unchanged amprenavir was below the limit of quantitation in feces and urine. Therefore, approximately 94% of the dose excreted in the feces was accounted for by these two metabolites. Concentrations of radiocarbon in the CSF were below the limit of quantitation in 5 of 6 subjects sampled. In summary, oral amprenavir is extensively metabolized in humans, with concentrations of unchanged drug below the limits of quantitation in urine and feces. The majority (75%) of administered radiocarbon was excreted in feces.

Use of the Dowell Bryant Incontinence Cost Index as a post-treatment outcome measure after non-surgical therapy

The aim of this study was to use the previously validated Dowell Bryant Incontinence Cost Index (DBICI) as a post-treatment outcome measure after non-surgical therapy and to determine whether the magnitude of reduced leakage would correlate with the magnitude of reduced personal cost. A simple urethral occlusive device (Femassist) was employed in 57 women with stress, urge, or mixed incontinence for 1 month. The DBICI was administered at baseline and after device use, along with a visual analogue scale (VAS) for severity of incontinence impact, a 3-day frequency volume chart (FVC) that documented leaks per 24 hours and pad usage, a 1-hour ICS pad test at standard volume, and two disease-specific quality of life measures (Urogenital Distress Inventory [UDI] and Incontinence Impact Questionnaire [IIQ]). The severity of leakage was significantly reduced on all parameters, and the median personal costs of incontinence fell from AU$6.52 per week (IQR 1.50-10.59) to a median of AU$ 1.57 per week (IQR 0-4.89). A significant correlation (Kendall's rank, tau) was observed between reduction in personal costs and reduction in VAS (tau = 0.24, P= 0.01), leaks/day (tau = 0.20, P = 0.03), pad test loss (tau = 0.29, P = 0.002), and quality of life scores (UDI, tau = 0.23, P = 0.01; IIQ, tau = 0.26, P = 0.005). The personal costs subset of the DBICI appears to be a useful outcome measure for urinary incontinence research and could be widely employed to assess the impact of continence treatments on the patient's economic burden.

Surgical resection for pulmonary metastases from colorectal cancer

BACKGROUND

Isolated pulmonary metastases from colorectal cancer are rare. The present study reports on the 15-year experience of the Royal Prince Alfred Unit and discusses means of improving survival outcomes.

METHODS

This was a retrospective review, over a 15-year period, of 41 patients who had resectable pulmonary metastases of colorectal origin.

RESULTS

Most were asymptomatic at the time of diagnosis. Seventy-two per cent had solitary metastases. The most common procedure performed was a lobectomy. Median follow up was 21 months. Five-year survival was 24%. There were no significant prognostic indicators except for the ability to achieve clear surgical margins.

CONCLUSION

Morbidity and mortality have not altered significantly over time. But an improved selection process such as the use of preoperative positron emission tomography will potentially improve survival outcomes.

Inadequate repeatability of the one-hour pad test: the need for a new incontinence outcome measure

OBJECTIVE

To assess the reproducibility of two one-hour pad tests performed within one week using serial ultrasound scanning to obtain identical bladder volumes, and to measure the effect of patient anxiety upon test reproducibility.

DESIGN

Prospective observational study.

SETTING

Tertiary urogynaecological unit.

SAMPLE

Fifty-six incontinent women undergoing 112 pad tests.

METHOD

Two one-hour pad tests were performed with natural diuresis one week apart prior to treatment. At the second test, serial ultrasound scans were performed until bladder volume reached that of the first test, followed by identical provocation.

MAIN OUTCOME MEASURES

One-hour pad loss, bladder volumes (Vol1, Vol2), anxiety VAS questionnaire.

RESULTS

Despite serial scanning, bladder volumes differed significantly. Median volume before second pad test was 541 mL, compared with 433 mls before first test (P < 0.001). The second pad test was also significantly larger than first (median 16g vs 4g, P = 0.017), and 13/56 (23%) women were dry on the first test but incontinent on the second. In 26 women (46%) both bladder volumes were similar, but the second pad loss was still significantly greater (median 14g vs 4g, P = 0.037). The mean difference between tests was 10g and the limits of agreement were wide (ranging from -44 to +66 g difference for the test result). Women were more anxious about leaking during the first test (Median VAS during the first test was 2.8cm, compared with 0.6cm during the second test, P = 0.008). 42.5% found the second test to be more typical.

CONCLUSION

In women with similar bladder volumes, the test-retest reliability of the one-hour pad test was judged to be clinically inadequate, as the first and second pad test could differ by -44 to +66g. Lower anxiety levels at the second test may account for this finding. The one-hour pad test is a useful baseline measure of incontinence, but the poor repeatability suggests that is not an optimal measure of post-treatment change.

Phosphorylation of nucleoside analog antiretrovirals: a review for clinicians

Nucleoside analogs (zidovudine, didanosine, zalcitabine, stavudine, abacavir, lamivudine) have been administered as antiretroviral agents for more than a decade. They undergo anabolic phosphorylation by intracellular kinases to form triphosphates, which inhibit human immunodeficiency virus replication by competitively inhibiting viral reverse transcriptase. Numerous methods are used to elucidate the intracellular metabolic pathways of these agents. Intracellular and extracellular factors affect intracellular phosphorylation. Lack of standardization and complexity of methods used to study phosphorylation in patients limit interpretation of study results and comparability of findings across studies. However, in vitro and in vivo studies give important insights into mechanisms of action, metabolic feedback mechanisms, antiviral effects, and mechanisms of toxicity, and have influenced dosing regimens of nucleoside analogs.

Pharmacokinetics and safety of escalating single and repeat oral doses of GW420867X, a novel non-nucleoside reverse transcriptase inhibitor

OBJECTIVE

To assess the pharmacokinetics, safety and tolerability of escalating oral doses of GW420867X, a non-nucleoside reverse transcriptase inhibitor, was investigated in healthy male volunteers in a randomized, double-blind placebo-controlled study.

METHODS

Study subjects were divided into four groups of 12 subjects (10, 50, 100 and 200-mg dose groups) with eight subjects from each group receiving active treatment and the remaining four matched placebo. Subjects were initially administered a single dose of GW420867X or placebo, and following a 24- to 28-day washout period, re-exposed to the same treatment for 14 consecutive days. Safety measurements including clinical laboratory evaluations, ECG and vital signs were performed before, during and after dosing.

RESULTS

Geometric mean GW420867X peak plasma concentrations (Cmax) following single oral doses of 10, 50, 100 and 200 mg were 160, 608, 1,000 and 1,662 ng/ml, respectively. Time to Cmax (tmax) increased from a median value of 1 h following the 10-mg dose, to 3 h after the 200-mg dose. Geometric mean plasma areas under the curves (AUC) were 4,325 (10 mg), 17,862 (50 mg), 35,295 (100 mg) and 62,338 ng/ml per hour (200 mg) and were proportionally less than the increase in the administered dose. Apparent terminal elimination half-life (t1/2) was approximately 50 h. Following repeat dosing, accumulation ratios based on plasma AUC were: 3.0+/-1.0 (10mg), 2.6+/-0.9 (50mg), 1.8+/-0.3 (100 mg) and 1.9+/-0.8 (200 mg) after 14 days of dosing compared to the corresponding single dose. In general, oral clearance (CL/F) was greater after 14 days and greater with higher doses except for the 10-mg dose group. Steady-state CL/F was 2.2, 3.4, 4.2, and 5.1 l/h for 10, 50, 100, and 200 mg, respectively. Steady-state was generally achieved within 7-10 days. Comparison of single and repeat dosing with GW420867X showed that Cmax increased by a factor of between 1.4 to 1.8, after 14 days of daily dosing to 288 (10 mg), 1,006 (50 mg), 1,401 (100 mg) and 2,613 (200 mg) ng/ml. These increases were proportionally less than the increase in the administered dose. GW420867X was well tolerated by subjects both after single and repeated dosing. Adverse effects reported by subjects on the active drug were similar to those receiving placebo. All episodes were rated as mild to moderate in severity and resolved spontaneously without further intervention.

CONCLUSION

The pharmacokinetic findings of this study imply that systemic exposure to GW420867X decreases with increasing dose and displays time-variant pharmacokinetics, which suggests decreased absorption and/or increased clearance of GW420867X. The relatively long plasma half-life, of approximately 50 h, makes it suitable for once-daily dosing.

Localization of messenger ribonucleic acid for adrenomedullin and adrenomedullin receptor in the human placenta in normal pregnancies and pregnancies complicated by oligohydramnios

OBJECTIVE

The purpose of this study was to identify the placental expression of adrenomedullin and adrenomedullin receptor messenger ribonucleic acid and compare them between placentas from pregnancies associated with oligohydramnios as a result of uteroplacental insufficiency and placentas from normal pregnancies.

STUDY DESIGN

Total ribonucleic acid was extracted from the amnion, chorion, cotyledon, umbilical vein, and umbilical artery in 5 normal placentas and 3 placentas from pregnancies complicated by oligohydramnios. A cell line known to express messenger ribonucleic acid of adrenomedullin and its receptor was used to optimize the polymerase chain reaction and served as a positive control preparation in all experiments. Semiquantitative reverse transcriptase-polymerase chain reaction results for adrenomedullin and adrenomedullin receptor were compared between tissues as densitometric ratios of adrenomedullin or adrenomedullin receptor messenger ribonucleic acid to beta(2)-microglobulin messenger ribonucleic acid. Results were analyzed with a Kruskal-Wallis 1-way analysis of variance. Immunohistochemical staining with an antibody to human adrenomedullin was used to localize adrenomedullin in all tissue types.

RESULTS

Messenger ribonucleic acid sequences for adrenomedullin and adrenomedullin receptor genes were identified in all tested placental tissue components. Within the normal placentas the expressions of adrenomedullin and adrenomedullin receptor messenger ribonucleic acid sequences did not differ statistically between the tissue components. Within placentas from patients with oligohydramnios the expressions of adrenomedullin and adrenomedullin receptor messenger ribonucleic acid did not differ statistically between the tissue components. When normal placentas were compared with placentas from pregnancies complicated by oligohydramnios, however, a 5-fold increase in adrenomedullin messenger ribonucleic acid and a 3-fold increase in adrenomedullin receptor messenger ribonucleic acid were seen in placentas from patients with oligohydramnios. Adrenomedullin immunoreactivity was present in all tissues studied.

CONCLUSION

The expression of messenger ribonucleic acid for both adrenomedullin and its receptor in these tissue components implies that placental tissues function in both synthesis and action of adrenomedullin. The increased adrenomedullin messenger ribonucleic acid expression in the umbilical artery and the elevated adrenomedullin receptor messenger ribonucleic acid expression in the cotyledons of placentas from patients with oligohydramnios may represent a local fetoplacental physiologic adaptive response to vascular compromise.

Angiotensin II in child urinary bladder: functional and autoradiographic studies

OBJECTIVES

To investigate the receptors for angiotensin II (AII, reported to be a potent contractile agent in human urinary bladder), using functional and autoradiographic techniques in child and adult bladder specimens. Materials and methods Bladder specimens were obtained from 61 children (aged 4 months to 12 years) undergoing ureteric reimplantation for vesico-ureteric reflux, and from 10 adults undergoing cystectomy. After overnight storage, the mucosa was removed and isometric contractions obtained from detrusor muscle strips in the presence of phosphoramidon (10 micromol/L). Only one concentration of AII was added to each preparation because of tachyphylaxis. The response to KCl (124 mmol/L) was 43% of that to carbachol (100 micromol/L). Sections of child bladder were radio-labelled with the ligand [125I]Sar1,Ile8-AII and binding sites visualized using emulsion autoradio- graphy.

RESULTS

The potency of AII was similar in child and adult detrusor strips, with mean (SEM) pD2 values of 6.9 (1.0) (n = 25) and 6.7 (0.2) (n = 9) respectively, and the maximum responses (to 10 micromol/L AII) rather low (39% and 49%, respectively, P > 0.05), compared with carbachol (100 micromol/L). There were no age- or gender-related differences. Responses to AII in strips from children under 3 years old were antagonized by the AT1 receptor antagonist losartan (1 micromol/L) but not by the AT2 receptor antagonist PD 123319 (1 micromol/L), indicating interaction with the AT1 receptor. Sections of child bladder radiolabelled with [125I]Sar1,Ile8-AII showed moderate specific binding over detrusor muscle and arterioles, with denser specific binding over subepithelial blood vessels. Specific binding was inhibited by co-incubation with losartan (10 micromol/L) but not with PD 123319 (10 micromol/L).

CONCLUSION

AII was a weak contractile agent of detrusor strips, with no significant differences in potency between child and adult bladder samples. These data show the presence of functional AT1 but not AT2 receptors in child detrusor smooth muscle.

The relative incidence of detrusor instability and bacterial cystitis detected on the urodynamic-test day

OBJECTIVE

To determine whether patients with detrusor instability (DI) were more likely to have bacterial cystitis or significant bacteriuria on the urodynamic-test day than were women with a stable bladder.

PATIENTS AND METHODS

A catheter specimen of urine was cultured (overnight in air) from 862 consecutive women at the time of urodynamic testing. The upper urinary tract was imaged, with cystoscopy when indicated, to exclude upper tract lesions or malignancy. The percentage of patients with pure idiopathic DI and those with mixed DI/genuine stress incontinence (GSI), in whom the urine culture was positive, was compared with the percentage who had a stable bladder (pure GSI or urodynamically normal) and a positive urine culture, both for the entire dataset and for women aged > or <65 years. Data were also analysed to detect the converse relationship; in those women found to have bacterial cystitis, the relative risk of being found urodynamically unstable or stable was determined.

RESULTS

The likelihood of bacterial cystitis occurring in patients with idiopathic DI (5.6%) was significantly greater than that in patients with GSI (1.1%; P = 0.009, Fisher's exact test). The proportion of patients with DI and significant bacteriuria (15. 4%) was significantly greater than that in patients with GSI (7.9%; P = 0.02). In patients with combined pure and mixed DI, bacterial cystitis was significantly more likely to occur (6.3%) than in GSI (P < 0.001), but bacteriuria was no more likely (12.5%, P = 0.09). Conversely, of those women found to have bacterial cystitis, the relative risk of having an unstable bladder was increased (+1.56), but for those with bacteriuria the relative risk of detrusor instability was not increased.

CONCLUSION

There was a significant association between idiopathic DI and bacterial cystitis, and we suggest that in some women with an unstable bladder, urinary infection may enhance detrusor contractility. Nevertheless, large-scale studies are needed of the temporal relationship between the onset of bacterial cystitis and the onset of DI.

Attitudes to vaginal/urethral touching and device placement in women with urinary incontinence

Because of recent development of a number of intravaginal and urethral occlusive devices for the treatment of urinary incontinence, we aimed to develop a linear analog scale that measured women's attitudes to becoming familiar with their genital anatomy and to placing devices into or upon the vagina or urethral orifices. We also investigated whether such attitudes were affected by previous tampon or diaphragm use, or were age dependent. After pilot studies, a 10-item questionnaire was given to 104 consecutive incontinent women, only 30% of whom were quite comfortable about the concept of touching their genitalia: this attitude was age dependent. Only 21% were quite willing to insert a continence device into their vagina: this attitude varied weakly with age but was significantly affected by previous tampon or diaphragm usage. Only 15% felt very comfortable about placing a continence device on to their urethra, but the likelihood of a positive response to this concept was not at all affected by age and was only slightly more common in previous tampon users. Thus older women are less likely to understand the anatomy of their genitalia or to be comfortable about the idea of exploring it, but age is no barrier to willingness to employ urethral or vaginal continence devices per se. We suggest that such a linear analog questionnaire may help gynecologists determine which patients might respond well to the use of vaginal or urethral continence devices.

Conservative management for urinary incontinence

Gynaecologists have become increasingly aware of the need to offer conservative therapy for genuine stress incontinence. There is good objective evidence from randomized controlled trials to support the use of supervised pelvic floor exercises. The efficacy of biofeedback therapy, vaginal cone weights and electrostimulation therapy is variable and requires further study to identify those women who will benefit the most. The mainstay of therapy for detrusor instability/sensory urgency remains bladder training, which has proven objective efficacy, but new treatments such as transcutaneous electrical nerve stimulation (TENS) offer promise. Finally, for certain groups of women with mixed stress and urge leak, a new range of vaginal and urethral devices provide useful additional options. The specific requirements for future research are discussed.

Oral zidovudine during labor to prevent perinatal HIV transmission, Bangkok: tolerance and zidovudine concentration in cord blood. Bangkok Collaborative Perinatal HIV Transmission Study Group

OBJECTIVES

To evaluate tolerance for the oral administration of zidovudine (ZDV) during labor and measure the resulting ZDV concentrations in umbilical cord blood.

DESIGN

A cross-sectional study of women in a placebo-controlled trial of short-course ZDV (twice a day from 36 weeks' gestation until labor and every 3 h during labor) to prevent perinatal HIV transmission in Bangkok.

METHODS

Umbilical cord blood was collected. Sixty control specimens and specimens from 372 women (182 in the ZDV group, 190 in the placebo group) were tested for ZDV by radioimmunoassay (lower detection limit < 1 ng/ml).

RESULTS

All women in the ZDV group took one or more labor dose, 170 (93%) took their last dose within 3 h of delivery, and only five (3%) experienced nausea or vomiting, a proportion similar to the placebo group. The median concentration of ZDV in the cord blood in the ZDV group was 252 ng/ml (range, < 1-1133 ng/ml); 31 (17%) specimens were less than 130 ng/ml (0.5 microM), the concentration thought to be active against HIV in vitro. Median concentrations were 189 ng/ml in specimens from women taking one or two labor doses, 290 ng/ml in those taking three or four doses, and 293 ng/ml in those taking more than four doses (P < 0.01). The ZDV concentration was not associated with time since the last dose, body weight, or perinatal transmission.

CONCLUSION

Oral intrapartum ZDV was feasible and well tolerated. Most ZDV concentrations in the cord blood after oral dosing during labor were at therapeutic concentrations but were lower than those reported after continuous intravenous administration. Although concentrations were not associated with perinatal transmission, these data do not exclude the possibility that intrapartum and neonatal chemoprophylaxis is effective.

A population pharmacokinetic analysis of zanamivir in subjects with experimental and naturally occurring influenza: effects of formulation and route of administration

The pharmacokinetics of zanamivir were evaluated in subjects from three phase I single-center and two phase II multicenter, randomized, double-blind, multidose, placebo-controlled trials. A total of 96 phase I subjects received zanamivir (3.6 to 16 mg) intranasally two or six times daily for 4 to 5 days beginning 4 hours before or 1 to 2 days after inoculation with influenza virus. A total of 75 phase II subjects with influenza or a history of exposure to naturally occurring influenza virus were administered zanamivir as an intranasal spray (3.4 mg/nostril), inhaled powder (10 mg), or combination of intranasal and inhaled formulations twice daily for 5 days. Population parameters (including demographic factors, zanamivir formulation, infection-related variables, and concurrent medication use) were estimated by a nonlinear mixed-effect modeling software program (NONMEM) using a one-compartment model with first-order absorption and conditional estimation algorithm. Formulation and route of administration were the most significant factors affecting the pharmacokinetics of zanamivir. Relative bioavailability of the inhaled powder to the intranasal drops and spray was 2.3 and 1.6, respectively. No significant differences in pharmacokinetic parameters were observed when demographic variables, indices of infection, or concurrent medication use were considered in either phase I or phase II population analyses.

In vitro contractile responses of detrusor to carbachol and neurokinin A, in children with recurrent urinary tract infection or day wetting

OBJECTIVE

To investigate whether a history of recurrent urinary tract infection (UTI) and/or the presence of day-wetting/urge symptoms might influence the contractile responses to the cholinergic agonist carbachol or to the sensory neuropeptide neurokinin A (NKA) in the urinary bladder in children.

PATIENTS AND METHODS

Small detrusor strips were taken from the margin of the cystotomy incision of the bladder dome during surgery to correct vesico-ureteric reflux (VUR) in 62 children (aged 4 months to 12 years) or for unrelated bladder conditions in five controls (aged 3 months to 13 years). Concentration-response curves to carbachol and NKA were constructed using organ-bath techniques, and results compared for age, sex, weight of the detrusor strip, UTI history or day-wetting syndrome.

RESULTS

The contractile responses to NKA were no different for any of the features investigated. The contractile response to carbachol and NKA in detrusor from control and VUR patients was not significantly different. The children with a history of UTI were significantly older than those without. The contractility in response to carbachol was greater in older girls (aged 4-12 years) than younger girls (< 4 years) and than in all boys (< 4 years and 4-12 years; ANOVA P = 0.013). The mean (SEM) maximum contractile response to carbachol in the group of 20 young children (4-30 months) with previous UTI was 3.0 (0.3) g, whereas the maximum response in the age-matched group of 11 without UTI was 1.8 (0.3) g (P = 0.046). There were no significant differences in maximum responses between those with day-wetting and those without (aged > 4 years), although there was a significant difference in pD2 value, at 6.19 (0.13) and 5.58 (0.14), respectively (P = 0.018).

CONCLUSION

Carbachol produced a larger contractile response in detrusor from children with a history of UTI than from those without, indicating possible alterations in muscarinic receptor characteristics. An increased sensitivity to muscarinic stimulation in day-wetting children was also suggested, whereas NKA is unlikely to be involved in any of these pathophysiological conditions.

Autoradiographic localization of tachykinin and calcitonin gene-related peptide receptors in adult urinary bladder

PURPOSE

In bladder, sensory afferent nerve fibers contain the "sensory neuropeptides" substance P (SP), neurokinin A (NKA) and calcitonin gene-related peptide (CGRP), which interact with tachykinin NK-1 and NK-2 receptors and CGRP receptors, respectively. The purpose of this study was to examine the autoradiographic distribution of these three receptor types in the human bladder, to determine whether the anatomic location of the receptors was consistent with their known functional roles.

MATERIALS AND METHODS

Specimens of urinary bladder from 9 patients (58-74 years) were obtained at cystectomy. Frozen sections of dome were labeled with [125I]-Bolton-Hunter [Sar9,Met(O2)11]-SP (NK-1 receptors), [125I]-[Lys5,Tyr(I2)7,MeLeu9,Nle10]-NKA(4-10) (NK-2 receptors) and [125I]-rat CGRP-I. Binding sites were visualized using emulsion autoradiography.

RESULTS

NK-1 receptors were found over the endothelium of arterial blood vessels within the detrusor muscle and lamina propria, and over small vessels in the subepithelium. NK-2 receptors were seen over the detrusor muscle and very sparsely over blood vessels, whereas CGRP receptors were expressed densely over the smooth muscle layer of arteries and arterioles, and weakly over collecting venules. NK-1 and CGRP receptors were not observed over the detrusor muscle.

CONCLUSIONS

Although the afferent nerves contain all three peptides, not all cell types express receptors for each peptide. The general distribution of receptors is in good agreement with the location of nerves, and with the known actions of SP and CGRP as vasodilator agents, and of NKA (but not SP or CGRP) in contracting the detrusor muscle.

Population pharmacokinetics of lamivudine in adult human immunodeficiency virus-infected patients enrolled in two phase III clinical trials

Lamivudine population pharmacokinetics were investigated by using nonlinear mixed-effect modelling (NONMEM) analysis of data from 394 human immunodeficiency virus (HIV)-infected patients treated with lamivudine (150 to 300 mg every 12 h) in two large, phase III clinical efficacy-safety trials, NUCA3001 and NUCA3002. Analyses of 1,477 serum lamivudine concentration determinations showed that population estimates for lamivudine oral clearance (CL/F; 25.1 liters/h) and volume of distribution (V/F; 128 liters) were similar to values previously reported for HIV-infected patients in phase I pharmacokinetic studies. Lamivudine CL/F was significantly influenced by the covariates creatinine clearance and weight and not affected by age, Centers for Disease Control and Prevention (CDC) classification, CD4(+) cell count, HIV type 1 (HIV-1) RNA PCR, or gender and race when CL/F was corrected for differences in patient weight. The population estimate for lamivudine V/F was not significantly influenced by the covariates gender, race, age, weight, renal function, HIV-1 RNA PCR, or CDC classification and CD4(+) cell count when creatinine clearance was included with CL/F in the model. Lamivudine disposition was significantly influenced by renal function. However, as only three patients had an estimated creatinine clearance of <60 ml/min, dosage adjustments for patients with impaired renal function should not be determined based on the population parameters derived in this analysis.

The pharmacokinetics of lamivudine phosphorylation in peripheral blood mononuclear cells from patients infected with HIV-1

OBJECTIVE

To assess the pharmacokinetics of lamivudine phosphorylation in peripheral blood mononuclear cells (PBMC) from patients infected with HIV-1.

DESIGN

Single-center, open-label, randomized, two-period, cross-over study in 10 asymptomatic, antiretroviral-experienced, HIV-1-infected patients who had a CD4+ lymphocyte count of 200-500 x 10(6)/l and had received combination treatment with lamivudine 150 mg twice a day plus zidovudine 600 mg a day (divided into two or three doses) for > or = 16 weeks prior to study entry.

METHODS

Patients were randomly assigned to receive lamivudine 150 mg twice a day or lamivudine 300 mg twice a day for 14 days, with at least a 48-h washout period between treatments. Serial blood samples were collected over 36 h for determination of lamivudine serum concentrations using liquid chromatography/mass spectrometry and intracellular phosphate PBMC concentrations using high performance liquid chromatography/radioimmunoassay methods. Pharmacokinetic parameters were calculated based on lamivudine and lamivudine anabolite concentration-time data.

RESULTS

Intracellular pharmacokinetic parameters were highly variable between patients (coefficient of variations approximately 50%). The two regimens produced lamivudine-total phosphate (totP) values of a similar magnitude. Although the 300-mg regimen tended to produce higher lamivudine-monophosphate (MP) and -triphosphate (TP) values, differences from values produced by the 150-mg regimen were not statistically significant. As lamivudine diphosphate (DP) was the predominant anabolite, accounting for 50-55% of lamivudine-totP (compared with 30-35% for lamivudine-MP and 15-20% for lamivudine-TP), the conversion of lamivudine-DP to lamivudine-TP can be regarded as the rate-limiting step. The median lamivudine-TP intracellular half-life (t1/2) for the 150-mg and 300-mg regimens did not differ significantly (15.3 and 16.1 h, respectively). Serum lamivudine pharmacokinetic parameters were consistent with those observed in previous studies in HIV-1-infected patients. No apparent linear relationships were observed between lamivudine intracellular anabolite and serum data.

CONCLUSIONS

The intracellular pharmacokinetics of lamivudine phosphorylation in PBMC from asymptomatic HIV-1-infected patients are highly variable and do not differ statistically between the 150- and 300-mg twice a day regimens. The variations in intracellular lamivudine-TP concentrations following these two lamivudine dosage regimens are unlikely to result in differences in clinical effect. This was confirmed by the results of a large phase III study in HIV-1-infected patients which showed no differences in HIV-1 RNA or CD4+ lymphocyte counts between the 150- and 300-mg lamivudine regimens in combination with zidovudine.

Efficacy and user acceptability of the urethral occlusive device in women with urinary incontinence

PURPOSE

We determine the efficacy and user acceptability of the urethral occlusive device (FemAssist) for incontinence for 1 month and identify factors that may predict successful use of the device.

MATERIALS AND METHODS

Baseline and posttreatment outcome measures included a 1-hour pad test, frequency volume chart (leakage, voiding and number of pads per 24 hour), visual analog scale for incontinence impact and quality of life (Urogenital Distress Inventory). The last 36 consecutive women also completed a linear analog scale about attitudes toward touching the genitalia.

RESULTS

The device was offered to 100 consecutive incontinent women of whom 3 did not enroll in the study and 57 (57%) completed the 1-month trial. Age, incontinence type or severity and attitudes about touching the genitalia were not significantly different between dropouts and participants. Only 13% of recruits were disinclined to place the device on the urethra. Significant reduction of incontinence was observed for all outcome measures with the device in situ. Pad testing revealed that 47% of the patients became continent and 33% had more than 50% benefit, while 9% had worse leakage. Those with severe baseline leakage were equally likely to respond as those with mild or moderate pad test loss. Women with stress, urge or mixed incontinence appeared to respond equally well.

CONCLUSIONS

The urethral occlusive device provides a further nonsurgical treatment option which is useful for a range of incontinence types.

Lamivudine/zidovudine as a combined formulation tablet: bioequivalence compared with lamivudine and zidovudine administered concurrently and the effect of food on absorption

A single-center, open-label, three-way crossover study was conducted in 24 healthy subjects to assess (1) the bioequivalence of a combined lamivudine 150 mg/zidovudine 300 mg tablet relative to the separate brand-name components administered concurrently and (2) the effect of food on the bioavailability of the drugs from the combination tablet. The subjects were randomly assigned to receive each of the following three treatments, separated by a 5- to 7-day washout period: one lamivudine/zidovudine combination tablet after an overnight fast, one lamivudine 150 mg tablet and one zidovudine 300 mg tablet simultaneously after an overnight fast, or one lamivudine/zidovudine combination tablet 5 minutes after completing a standardized high-fat breakfast (67 g fat, 58 g carbohydrate, and 33 g protein). Serial blood samples were collected up to 24 hours postdose for the determination of lamivudine and zidovudine plasma concentrations. Standard pharmacokinetic parameters were estimated. Treatments were considered bioequivalent if 90% confidence intervals for the ratio of least squares (LS) means for the lamivudine and zidovudine area under the plasma concentration-time curve (AUC infinity) and maximum observed plasma concentration (Cmax) fell entirely within 0.80 to 1.25 for log-transformed parameters. The combined lamivudine/zidovudine tablet was bioequivalent in the extent (AUC infinity) and rate of absorption (Cmax and time of Cmax [tmax]) to the individual brand-name drug components administered concurrently under fasted conditions. Geometric LS mean ratios and 90% confidence intervals for AUC infinity and Cmax were 0.97 (0.92, 1.03) and 0.94 (0.84, 1.06), respectively, for lamivudine and 0.99 (0.91, 1.07) and 0.97 (0.82, 1.15), respectively, for zidovudine. The extent of absorption of lamivudine and zidovudine from the combination tablet was not altered by administration with meals, indicating that this formulation may be administered with or without food. However, food slowed the rate of absorption, delayed the tmax, and reduced the Cmax of lamivudine and zidovudine. These changes were not considered clinically important. All formulations were well tolerated under fasted and fed conditions.