The role of platelet-rich plasma in androgenetic alopecia: A systematic review

BACKGROUND

Androgenetic alopecia (AGA), also referred to as male or female pattern hair loss, is the commonest cause of chronic hair loss and affects up to 80% of men by the age of 70. Despite a high prevalence, there are few approved therapies, which show minimal efficacy.

OBJECTIVES

This systematic review aims to evaluate the efficacy of platelet-rich plasma (PrP) in the treatment of AGA in male patients.

METHODS

MEDLINE, EMBASE, Cochrane (CENTRAL), CINAHL, clinicaltrials.gov, Google Scholar and the Science Citation Index database were searched to identify eligible studies. All randomized controlled trials (RCTs) and prospective cohort studies related to PrP use in AGA were included. Primary outcomes included changes in hair density and hair count. Methodological quality was assessed using bias assessment tools.

RESULTS

Eight RCTs and one cohort study were included in the review with a total of 291 participants. Six studies reported a statistically significant increase in hair density in the PrP group versus the control. Five studies reported a statistically significant increase in hair count with PrP. Seven studies showed moderate risk and two showed low risk of bias.

CONCLUSION

In a methodologically robust review on the effectiveness of PrP on male AGA, PrP demonstrated some potential to be used therapeutically. However, the low quality of evidence, moderate risk of bias, and high heterogeneity of included studies limit inferences and call for more robust designs to investigate this further.

Siriraj I Gγ(Aγδβ)0-thalassaemia causing severe thalassaemia intermedia in compound heterozygous state with IVS1-1(G→T) mutation

The Siriraj I ^Gγ(^Aγδβ)⁰-thalassaemia is a novel mutation involving a 118kb deletion of the β-globin gene cluster. It was first reported in 2012 in two unrelated families from the southern part of Thailand. The carriers in the heterozygous state are clinically asymptomatic. Nonetheless, its complex interaction with other β-thalassaemia could give rise to different clinical phenotypes, ranging from mild thalassaemia intermedia to thalassaemia major. We report here a case of a six-year-old Malay boy, presented with pallor, growth failure and hepatosplenomegaly. His haemoglobin at presentation was 9.2g/dL with a mean cell haemoglobin of 22.6pg and a mean cell volume of 69.9fl. His peripheral blood smear showed features of thalassaemia intermedia. Haemoglobin (Hb) analysis revealed markedly raised Hb F (83%), normal HbA2 levels and absent HbA. Deoxyribonucleic acid (DNA) analysis showed compound heterozygous IVS1-1 (G→T) β-globin gene mutation and Siriraj I ^Gγ(^Aγδβ)⁰-deletion (genotype β^IVS1-1/ β ^{Siriraj I deletion}). Both his father and elder sister are carriers of Siriraj I ^Gγ(^Aγδβ)⁰-thalassaemia while his mother carries IVS1-1 (G→T) gene mutation. Clinically, the patient is transfusion dependent on six weekly regime. To the best of our knowledge, this is the first reported case in Malaysia involving unique Siriraj I ^Gγ(^Aγδβ)⁰-thalassaemia and IVS1-1 (G→T) in a compound heterozygous state. In summary, detection of Siriraj I ^Gγ(^Aγδβ)⁰-thalassaemia is essential as this deletion can lead to severe disease upon interaction with a β-thalassemia point mutation as demonstrated in our case. The establishment of effective carrier screening and genetic counselling is important to prevent its adverse consequences.

Factors influencing patients' hypertension self-management and sustainable self-care practices: a qualitative study

OBJECTIVE

The objective of this study was to explore factors influencing patients with hypertension to participating in a hypertension self-management education (HSME) programme and challenges of sustaining the learnt self-care practices.

STUDY DESIGN

This was a qualitative study with focus group discussions.

METHODS

Focus group discussions using a semistructured moderator guide were conducted among participants who had attended the HSME programme. Data were audio recorded, transcribed verbatim and analysed using a thematic analysis approach.

RESULTS

Three focus groups involving 19 participants were conducted. Four major themes emerged from the data collected. Most participants enjoyed the group-based HSME sessions because sharing experiences with those having similar health problems can reduce their sense of isolation. However, the participants highlighted the difficulty in sustaining self-care practices in the presence of friends and family influences.

CONCLUSION

A number of patient-, family- and community-level motivators and barriers to patients' hypertension self-management have been identified. Efforts to tailor behavioural interventions to sustain daily self-care activities during social and cultural events are imperative.

Short- and long-term cure rates of short-duration trimethoprim-sulfamethoxazole treatment in female dogs with uncomplicated bacterial cystitis

Background

Long‐duration beta‐lactam antibiotics are used for empirical treatment in female dogs with uncomplicated bacterial cystitis. However, women with bacterial cystitis are treated with short‐duration potentiated sulfonamides because longer courses of beta‐lactams result in lower cure and higher recurrence rates.

Hypothesis/Objectives

Short‐duration potentiated sulfonamide treatment is more efficacious than long‐duration beta‐lactam treatment in achieving clinical and microbiological cures in female dogs with uncomplicated bacterial cystitis.

Animals

Thirty‐eight client‐owned female dogs.

Methods

Randomized, double‐blinded, placebo‐controlled clinical trial. Dogs were treated with TMP‐SMX (15 mg/kg PO q12h for 3 days followed by a placebo capsule PO q12h for 7 days; Group SDS; n = 20) or cephalexin (20 mg/kg PO q12h for 10 days; Group LDBL; n = 18). Dogs were monitored for clinical and microbiological cure during treatment and at short‐ and long‐term follow‐up.

Results

No statistically significant differences were found between treatment groups in clinical cure rates after 3 days of treatment (89% SDS, 94% LDBL; P = 1.00) and 4 days (85% SDS, 72% LDBL; P = .44) or >30 days (50% SDS, 65% LDBL; P = .50) after conclusion of treatment or in microbiological cure rates 4 days (59% SDS, 36% LDBL; P = .44) or >30 days (44% SDS, 20% LDBL; P = .40) after conclusion of treatment.

Conclusions and Clinical Importance

We did not identify a difference in cure rates between short‐duration sulfonamide and long‐duration beta‐lactam treatments in female dogs with uncomplicated cystitis. Long‐term cure rates in both treatment groups were low. In some female dogs, “uncomplicated” bacterial cystitis may be more complicated than previously recognized.

Tears evaluation of one sample of keratoconus patients in kuala lumpur

OBJECTIVE

To evaluate tears of newly diagnosed keratoconus patients attending the Optometry clinic in Malaysia and to compare this with tears of normal myopic subjects.

METHODS

The ocular surface of newly diagnosed keratoconus patients were evaluated using tear break up time (TBUT) test, non invasive tear break up time test (NIBUT) and Schirmer test. Twenty keratoconus patients (40 eyes) and 40 normal subjects (80 eyes) participated in this study.

RESULTS

Significantly lower TBUT and NIBUT values were found in keratoconus patients than normal control subjects (p<0.05). Mean TBUT and NIBUT for keratoconus patients were 3.99±1.69s and 7.03±3.48s and for normal subjects were 7.24±4.39s and 13.67±10.81s respectively. However, no significant difference was detected in Schirmer test values. Mean values of Schirmer tests I and II for keratoconus patients were 20.52±10.66mm and 10.71±10.43mm and for normals were 23.83±11.34mm and 13.27±8.28mm accordingly.

CONCLUSION

It was concluded from this study that keratoconus patients have poor tear stability which need to be considered appropriately during management of the patients.

Antiinflammatory and antinociceptive activities of Zingiber zerumbet methanol extract in experimental model systems

OBJECTIVE

The present study was carried out to determine the antiinflammatory and antinociceptive activities of a methanol extract of Zingiber zerumbet rhizomes (MEZZ) using various experimental model systems.

MATERIALS AND METHODS

The MEZZ was prepared by macerating oven-dried (50 degrees C) powdered rhizomes (1.2 kg) of Z. zerumbet in 80% methanol in a ratio of 1:20 (w/v) for 48 h. The supernatant was collected, filtered and evaporated to dryness under reduced pressure (50 degrees C) yielding approximately 21.0 g of the crude dried extract. The crude dried extract was stored at -20 degrees C prior to use and was dissolved in normal saline (0.9% NaCl) immediately before administration at concentrations required to produce doses of 25, 50 and 100 mg/kg.

RESULTS

All dosages of MEZZ showed significant (p < 0.05) antiedema activity when assessed using the carrageenan-induced paw edema test and the cotton-pellet-induced granuloma test. The MEZZ exhibited significant (p < 0.05) antinociceptive activity when assessed by the writhing, hot plate and formalin tests. Pretreatment with naloxone (5 mg/kg) significantly decreased the latency of discomfort produced by the 100 mg/kg dose of MEZZ in the hot plate test.

CONCLUSION

MEZZ produced antiinflammatory and antinociceptive activities which may involve the inhibition of bradykinin-, prostaglandin-, histamine- and opioid-mediated processes.

Refractory thrombotic thrombocytopenic purpura and membranoproliferative glomerulonephritis successfully treated with rituximab: a case associated with hepatitis C virus infection

Plasmapheresis remains the main treatment modality for patients with thrombotic thrombocytopenic purpura. We report a patient who had simultaneous onset of membranoproliferative glomerulonephritis and thrombotic thrombocytopenic purpura. She did not improve after 48 plasmapheresis sessions. A 6-week course of weekly intravenous doses of rituximab was then given. This achieved complete remission of her nephrotic syndrome and improvement in her renal function, so plasmapheresis was ceased. She had a low ADAMTS13 antigen level and a positive ADAMTS13 antibody, both of which reverted to normal after treatment with rituximab. This coincided with a rise in her hepatitis C virus RNA and liver transaminases. Liver biopsies did not reveal active fibrosis. Her hepatitis C virus RNA titre dropped afterwards, and she had no relapses of her thrombotic thrombocytopenic purpura and nephrotic syndrome, for more than 2 years after remission. The simultaneous onset and successful outcomes of both the membranoproliferative glomerulonephritis and thrombotic thrombocytopenic purpura illustrate the usefulness of rituximab. We discuss its use and risks, in the context of chronic hepatitis C infection.

The neuropeptide Y (NPY) Y2 receptors are largely dimeric in the kidney, but monomeric in the forebrain

The neuropeptide Y(NPY) Y2 receptors are detected largely as dimers in the clonal expressions in CHO cells and in particulates from rabbit kidney cortex. However, in two areas of the forebrain (rat or rabbit piriform cortex and hypothalamus), these receptors are found mainly as monomers. Evidence is presented that this difference relates to large levels of G proteins containing the Gi alpha -subunit in the forebrain areas. The predominant monomeric status of these Y2 receptors should also be physiologically linked to large synaptic inputs of the agonist NPY. The rabbit kidney and the human CHO cell-expressed Y2 dimers are converted by agonists to monomers in vitro at a similar rate in the presence of divalent cations.

Transarterial ethanol ablation of unresectable hepatocellular carcinoma with lipiodol-ethanol mixture (LEM): A phase II study

14054

Background: Transarterial ablation with lipiodol-ethanol mixture (LEM) induced potent dual embolization of arterioles and portal venules in preclinical studies, and extensive tumor necrosis in clinical studies. It is potentially an effective treatment and a better alternative to chemoembolization for unresectable hepatocellular carcinoma (HCC). The authors aim to study the safety and efficacy of this treatment. Methods: Unresectable HCC diagnosed by histology or viral serology + AFP > 500 ug/l + typical imaging; bilirubin ≤ 30 umol/l; hypervascular tumor on CT / angiogram, no vascular invasion or extrahepatic spread. LEM with Lipiodol and ethanol mixed in ratio of 2:1 by volume was infused transarterially into tumor vasculature by superselective catheterization of tumor feeders at a subsegmental level under fluoroscopy until flow stagnation. Adverse events (AE) graded by NCI-CTC V2.0. Tumor response monitored by CT scan q3m. LEM repeated for residual enhancing lesion or intrahepatic progression on CT scan. Primary endpoint was response rate. Secondary endpoints: toxicity and survival. Results: From 7/2001 to 4/2005, 77 pts enrolled. Age 28–85 (median 64). M:F=60:17. ECOG 0=68; 1=9. Cirrhosis 92%. HBV 77%, HCV 14%, alcohol 4%. Child A 88%, B 12%. Okuda A 73%, B 27%. Histology confirmed in 78%. 39% had previous treatment. Median tumor size 4.5cm (range 1.5–15cm); Number of lesions: One (58), Two (14), Three (5). Best tumor response (WHO criteria): CR 0%, PR 43%, MR 36%, SD 17%, PD 4%. Patients received 1 to 8 LEM treatments (mean 2.2). Mean hospital stay 2.7 days (range 2 -15). Significant AEs are shown in the table. Fever in 15% for mean duration of 3.1 days. After a median follow-up of 1.65 yr, 23 pts died. One year survival 77%. 3 pts had tumor resection after downstage by LEM. Conclusions: Transarterial ablation with LEM is a well tolerated and effective local regional treatment of unresectable HCC. The high tumor response and 1-year survival rate warrants further investigation in comparative study. [Table: see text]

No significant financial relationships to disclose.

Intravenous leiomyomatosis: computed tomography diagnosis

Intravenous leiomyomatosis is a rare neoplastic condition characterised by nodular masses of histologically benign smooth muscle growing within veins. In most cases, the disease is confined to the pelvic veins, but involvement may extend to the inferior vena cava and right heart chamber. We report the computed tomography features of a woman who developed extensive intravenous leiomyomatosis and lung metastases, and presented with acute-onset lower limb swelling.

The importance of the interpretation of urine catecholamines is essential for the diagnosis and management of patient with dopamine-secreting paraganglioma

Phaeochromocytoma or paraganglioma that exclusively secretes dopamine is very rare. This case illustrates its atypical presentation and the importance of interpretative reporting for urine catecholamines leading to the diagnosis and subsequent management of a patient with this condition. We report a 71-year-old Chinese woman with a large dopamine-secreting paraganglioma. She presented with low back pain for six months. On examination, a right abdominal mass was palpable incidentally. Her blood pressure was normal throughout. Serial 24-h urine collections for catecholamines showed enormous elevation of urine dopamine excretion to 80.7 micromol/day (normotensive:<2.6 m mol/day). However, the daily excretions of urine adrenaline and noradrenaline, as well as their metabolites were within their respective reference intervals. Good communication between chemical pathologists and physicians prompted the arrangement of the whole body 131I-meta-iodobenzylguanidine (MIBG) scintigraphy, which showed a large signal in the right upper quadrant of the abdomen corresponding to a large extra-adrenal tumour detected by both ultrasonography and computerized tomography (CT) of the abdomen. Histological section of the tumour tissue revealed paraganglioma, which stained positive for chromogranin and neuron-specific enolase. After four months, the patient presented with chest symptoms and CT of the thorax revealed multiple nodules. Lung metastases were suspected. However, follow-up urine catechola- mine and dopamine excretions were again within their respective normotensive reference intervals. A second MIBG scintigraphy was performed, but no specific uptake at either the thorax or the abdomen could be demonstrated. Fine-needle aspiration cytology using the thoracoscopic technique was performed and immunochemical staining of the biopsy specimen showed the presence of non- small-cell carcinoma of the lung.

Liver Resection after Irinotecan, 5-Fluorouracil, and Folinic Acid for Patients with Unresectable Colorectal Liver Metastases: A Multicenter Phase II Study by the Cancer Therapeutic Research Group

The main objectives of this study were to assess the use of irinotecan, 5-fluorouracil (5-FU), and leucovorin (FA) as neoadjuvant chemotherapy for patients with unresectable colorectal liver metastases and to determine the response rate and proportion of patients that could be down-staged to resectable tumors. Forty patients were treated with irinotecan (180 mg/m2 over 30 min) on d 1, FA (200 mg/m2 over 30 min) followed by 5-FU (400 mg/m2 bolus and continuous infusion of 600 mg/m2 over 22 h) on d 1 and 2 every 2 wk. The overall response rate was 55% (95% CI: 39.5-70.4%). The progression-free survival was 12.1 mo (95% CI: 11.4-14.8 mo). The median overall survival was 20 mo (95% CI: 17.7-26.6 mo). Four patients (10%) have undergone liver resection after a median of eight cycles. Those patients remained alive with a median follow up period of 33 mo. The principal grade 3-4 toxicity was neutropenia in 20 patients (50%). We conclude that the regimen of irinotecan/5-FU/FA was highly active in patients with colorectal cancer and liver metastases with limited toxicity. In a subgroup of patients with initial inoperable liver metastases, this regimen was able to down-stage the disease to an operable stage.

Immunosensor for the differentiation and detection of Salmonella species based on a quartz crystal microbalance

Immunosensors based on the microgravimetric quartz crystal microbalance (QCM) technique have been developed for the detection of Salmonella species from serogroups A, B and D. Salmonella serogroup-specific murine monoclonal antibodies, respectively, raised against these serogroups were immobilized onto the silver electrodes of piezoelectric (PZ) crystals by cross-linkage via glutaraldehyde (GA) to the electrode surfaces pre-coated with thin polyethyleneimine (PEI) layer. The specific immunosensors developed gave responses in linear ranges from 10(5) to 5x10(8) cells per ml with no significant interference from other strains of Salmonella and Escherichia coli up to 10(8) cells per ml. They showed good repeatability and excellent linear range, achieving detection limits down to 10(4) cells per ml with ability to distinguish different strains of Salmonella. These biosensors exhibited an exquisite specificity evidenced by their ability to discriminate antigens, the structures of which differ only by the isomeric form of di-deoxyhexose. The antibody-modified crystals showed no loss in activity over 4 days under storage at 4 degrees C.

Self-assembled monolayers as the coating in a quartz piezoelectric crystal immunosensor to detect Salmonella in aqueous solution

A new procedure based on the self-assembled monolayers (SAM) of alkanethiols was developed to immobilize antibodies onto gold electrodes of a quartz crystal microbalance (QCM) for detecting Salmonella paratyphi A. The procedure includes (1) chemisorption of 3-mercaptopropionic acid (MPA) at electrode surfaces to produce a carboxylic acid terminated monolayer, (2) activation by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydrosuccinimide (NHS) to generate a stable acyl amino ester intermediate, and (3) condensation of antibodies after aminolysis of the NHS adduct. Activation by two coupling agents (EDC and NHS) was shown to enhance the stability of the coating and facilitate the formation of a suitable intermediate to condense antibodies reproducibly and densely at the SAM, leading to high sensitivity and good precision of the developed immunosensor. With 50 min incubation under continuous monitoring, working ranges from 10(2) to 10(5) cells/mL with repeatability < 10% RSD were obtained. On the basis of S/N = 3, the detection limit was 1.7 x 10(2) cells/mL The MO2 piezoimmunosensor developed was specific to differentiate S. paratyphi A against Escherichia coli and other serogroups of Salmonella that are commonly present together.

The bioavailability of ginkgolides in Ginkgo biloba extracts

A new Ginkgo biloba leaf extract, BioGinkgo 27/7, was prepared using a method that enriches ginkgolide B. The bioavailability of ginkgolides in these extracts was assessed in rabbits in comparison with a commercially available standardized 24/6 extract. It was found that, after a single dose, a higher concentration of ginkgolides was maintained for a longer period of time with these extracts than was found with commercial extract prepared by existing methods.

Preventive and promotive medicine in ambulatory clinical practice: a prospective simulated patient study

OBJECTIVE

This study examines the extent to which preventive and promotive advice is integrated into the clinical practice of doctors.

STUDY DESIGN

Using a cross-sectional descriptive survey design, the study compares the performance of doctors in giving healthy lifestyle advice for five clinical conditions, their perceived practice and their rating on the importance of disseminating selected key lifestyle messages.

DATA EXTRACTION METHODS

A total of 28 volunteers were trained to simulate the five clinical conditions which required related health advice and to rate the doctors' performance with the use of a prepared checklist. Simulated patient ratings of 343 doctor-patient encounters provided the data on doctors' health promotion efforts for the selected clinical conditions. A post-visit self-administered questionnaire survey of a sub-sample of 100 doctors gave an insight into their opinions and perceived practice.

PRINCIPAL FINDINGS

Only in 49% of the instances was a health promotion message given. The doctors' encouraging interest in health education and health promotion and their positive perceptions of their volume of healthy lifestyle counselling were not borne out in actual clinical practice.

CONCLUSIONS

The results indicate that the extent of preventive and promotive health education in both the public and private health sectors is unacceptably low. The matter needs to be addressed through training programmes as well as the formulation of clear health promotion priorities and strategies in Malaysia.

Steady-state fluctuation and variability of betaxolol and atenolol plasma levels

Twenty-four nonsmoking male volunteers took 50 mg atenolol or 10 mg betaxolol orally once a day for 9 days in a two-period, four-sequence, randomized, crossover study. Plasma concentrations reached steady state after day 5. Percent fluctuation in plasma concentration defined as (Cmax-Cmin)/Cavg (% fluctuation 1) was 97% on day 9 for betaxolol and 343% for atenolol; thus atenolol fluctuation was more than threefold that of betaxolol. A 10-fold difference in plasma level fluctuation was observed when fluctuation was defined as (Cmax-Cmin)/Cmin (% fluctuation 2). The intersubject variances for % fluctuation 1 and % fluctuation 2 were 4.1 and 85.5 times greater for atenolol than for betaxolol; these differences were marginally statistically significant for % fluctuation 1 and significant for % fluctuation 2. The intrasubject variabilities for area under the curve and plasma level fluctuations were statistically greater for atenolol than for betaxolol. Atenolol intrasubject variances were 25 and 271 times greater than for betaxolol for % fluctuation 1 and % fluctuation 2, respectively. Thus, betaxolol exhibited less fluctuation in plasma levels with substantially less intersubject and intrasubject variability. These factors would be expected to provide a more consistent therapeutic response and more dependable dosage adjustment.

Changing use patterns of plasma volume expanders through educational intervention

Use patterns of the plasma volume expanders albumin and hetastarch were evaluated before and after an educational program promoting the preferential use of hetastarch was implemented in a 700-bed teaching hospital. The high acquisition cost and periodic shortages of 5% albumin injection prompted the implementation in March 1985 of a target drug program that would encourage the use of 6% hetastarch injection in place of albumin whenever possible. Purchases of albumin and hetastarch were monitored from August 1984 to March 1985 and again from April to November 1985 to determine how much and where these agents were being used. Criteria and guidelines for the use of plasma volume expanders were developed by the pharmacy with physician input. Senior attending physicians who had been identified as primary decision makers in the clinical use of albumin were asked to abide by the guidelines; also, pharmacists conducted inservice educational programs on the use of hetastarch. Patterns of albumin and hetastarch use changed significantly (p less than 0.05) after the educational program was implemented. From August 1984 to March 1985, the mean number of units of albumin and hetastarch purchased monthly were 325.5 and 0.4, respectively. These numbers changed to 195.3 and 163.1 units, respectively, from April to November 1985. The monthly cost avoidance associated with this change was $5127, which extrapolates to $61,526 annually. An educational program can be effective in controlling hospital expenditures for plasma volume expanders. However, clinicians should be aware of the potential adverse effects of hetastarch and should avoid using it in excessive amounts or in patients with underlying coagulopathies.

Severe thrombocytopenia associated with phenytoin and cimetidine therapy

A 67-year-old man developed a sudden onset of severe isolated thrombocytopenia (platelet count, 1000/mm3) after 10 days of phenytoin administration as a prophylactic measure prior to craniotomy. The patient had also been taking cimetidine for 2 months prior to admission. No other hematological complications were noted, and an extensive hematologic investigation was otherwise unremarkable. Rapid resolution of the thrombocytopenia upon discontinuation of phenytoin and cimetidine strongly suggests a drug-induced adverse reaction.

Plasma protein binding of warfarin: methodological considerations

Recent theoretical work has suggested that radiochemical impurities can significantly alter the binding results for highly protein-bound drugs. We compared protein binding of warfarin by ultrafiltration and equilibrium dialysis with 98% radiochemically pure [14C]warfarin. Ultrafiltration and equilibrium dialysis were performed at 37 degrees C and pH 7.45 on the plasma of patients receiving chronic warfarin therapy. Binding to plasma from seven patients were measured in duplicate by both a nonspecific radioisotopic technique and a specific HPLC technique. The nonspecific technique gave percentage of free warfarin values of 1.84 +/- 0.11 (mean +/- SD) and 1.59 +/- 0.14 for ultrafiltration and equilibrium dialysis, respectively. The HPLC procedure yielded a percentage of free warfarin by ultrafiltration of 0.969 +/- 0.203 and a value of 0.690 +/- 0.095 by equilibrium dialysis (p less than 0.05). The HPLC procedure for protein binding was performed on plasma samples from 12 additional patients and yielded a percentage of free warfarin of 1.01 +/- 0.69 by ultrafiltration and 0.44 +/- 0.34 by equilibrium dialysis (p less than 0.05). It can be concluded that radiochemical impurities may lead to significant overestimation of the percentage of free warfarin. Ultrafiltration yielded a higher percentage of free warfarin than did equilibrium dialysis, but the ability to distinguish binding differences among patients was similar.

Effect of erythromycin on carbamazepine kinetics

Two recent reports of carbamazepine-induced intoxication during concurrent therapy with macrolide antibiotics prompted us to perform a carefully controlled two-way cross-over study in eight healthy male nonsmokers. Treatment A was 250 mg erythromycin every 6 hr for 5 days before and 3 days after 400 mg carbamazepine. Treatment B was 400 mg of carbamazepine alone. One half of the subjects received treatment A, then B, while the other half received treatment B, then A. There was a 4-wk washout period between treatments. Plasma samples obtained at various times up to 72 hr after the carbamazepine dose were assayed in duplicate by HPLC. The data were fit to a one-compartment open model with first-order absorption and elimination. Clearance of oral carbamazepine was lower in the presence of erythromycin (mean +/- SD, 0.290 +/- 0.074 and 0.360 +/- 0.072 1 X kg-1 X day-1). There were no differences in apparent volume of distribution (1.01 +/- 0.20 and 1.04 +/- 0.12 1 X kg-1), elimination rate constant (0.302 +/- 0.113 and 0.348 +/- 0.079 day-1), or absorption rate constant (14.5 +/- 8.7 and 15.5 +/- 16.6 day-1) between the two treatment groups. The decrease in clearance of oral carbamazepine secondary to erythromycin indicates that further clinical studies are warranted.

Propranolol plasma concentrations and plasmapheresis

Propranolol plasma concentrations were determined in a patient with hemolytic-uremic syndrome undergoing plasmapheresis before and after the procedure on three occasions. The mean half-life and elimination rate constant during plasmapheresis were estimated to be 25.6 percent of the values obtained without plasmapheresis. These changes suggest that plasmapheresis may influence propranolol disposition.