UGT2B17 genetic polymorphisms dramatically affect the pharmacokinetics of MK-7246 in healthy subjects in a first-in-human study

MK-7246, an antagonist of the chemoattractant receptor on T helper type 2 (Th2) cells, is being developed for the treatment of respiratory diseases. In a first-in-human study, we investigated whether genetic polymorphisms contributed to the marked intersubject variability in the pharmacokinetics of MK-7246 and its glucuronide metabolite M3. Results from in vitro enzyme kinetic studies suggested that UGT2B17 is probably the major enzyme responsible for MK-7246 metabolism in both the liver and the intestine. As compared with those with the UGT2B17*1/*1 wild-type genotype, UGT2B17*2/*2 carriers, who possess no UGT2B17 protein, had 25- and 82-fold greater mean dose-normalized values of area under the plasma concentration–time curve (AUC) and peak concentration of MK-7246, respectively, and a 24-fold lower M3-to-MK-7246 AUC ratio. The apparent half-life of MK-7246 was not as variable between these two genotypes. Therefore, the highly variable pharmacokinetics of MK-7246 is attributable primarily to the impact of UGT2B17 genetic polymorphisms and extensive first-pass metabolism of MK-7246.

Lack of pharmacokinetic interaction between rofecoxib and methotrexate in rheumatoid arthritis patients

Rofecoxib is a highly selective and potent inhibitor of cyclooxgenase-2 (COX-2). Methotrexate is a disease-modifying agent with a narrow therapeutic index frequently prescribed for the management of rheumatoid arthritis. The objective of this study was to investigate the influence of clinical doses of rofecoxib on the pharmacokinetics of methotrexate in patients with rheumatoid arthritis. This was a randomized, double-blind, placebo-controlled study in 25 rheumatoid arthritis patients on stable doses of methotrexate. Patients received oral methotrexate (7.5 to 20 mg) on days -1, 7, 14, and 21. Nineteen patients received rofecoxib 12.5, 25, and 50 mg once daily on days 1 to 7, 8 to 14, and 15 to 21, respectively. Six patients received placebo on days 1 to 21 only to maintain a double-blinded design for assessment of adverse experiences. Plasma and urine samples were analyzed for methotrexate and its major although inactive metabolite, 7-hydroxymethotrexate. The AUC(0-infinity) geometric mean ratios (GMR) and their 90% confidence intervals (90% CI) (rofecoxib + methotrexate/methotrexate alone) for day 7/day -1, day 14/day -1, and day 21/day -1, for rofecoxib 12.5, 25, and 50 mg, were 1.03 (0.93, 1.14), 1.02 (0.92, 1.12), and 1.06 (0.96, 1.17), respectively (p > 0.2 for all comparisons to day -1). All AUC(0-infinity), GMR and Cmax GMR 90% CIs fell within the predefined comparability limits of (0.80, 1.25). Similar results were observed for renal clearance of methotrexate and 7-hydroxymethotrexate at the highest dose of rofecoxib tested (50 mg). It was concluded that rofecoxib at doses of 12.5, 25, and 50 mg once daily has no effect on the plasma concentrations or renal clearance (tested at the highest dose of rofecoxib) of methotrexate in rheumatoid arthritis patients.

Simvastatin does not affect CYP3A activity, quantified by the erythromycin breath test and oral midazolam pharmacokinetics, in healthy male subjects

Potential for inhibition of CYP3A activity by simvastatin, an HMG-CoA reductase inhibitor, was evaluated in 12 healthy male subjects who received placebo or 80 mg of simvastatin, the maximal recommended dose, once daily for 7 consecutive days. On day 7, an intravenous injection of 3 microCi [14C N-methyl]erythromycin for the erythromycin breath test (EBT) was coadministered with a 2 mg oral solution of midazolam. The values for percent 14C exhaled during the first hour (for EBT) and the pharmacokinetic parameters of midazolam (AUC, Cmax, t1/2) were not affected following multiple once-daily oral doses of simvastatin 80 mg. The 95% confidence interval was 0.97 to 1.18 for EBT and 0.99 to 1.23 for midazolam AUC. In addition, the total urinary recoveries of midazolam and its 1'-hydroxy metabolites (free plus conjugate) obtained from both treatments were not statistically different (p > 0.200). These data demonstrate that multiple dosing of simvastatin, at the highest recommended clinical dose, does not significantly alter the in vivo hepatic or intestinal CYP3A4/5 activity as measured by the commonly used EBT and oral midazolam probes.

Comparative inhibitory activity of rofecoxib, meloxicam, diclofenac, ibuprofen, and naproxen on COX-2 versus COX-1 in healthy volunteers

Steady-state inhibitory activity of rofecoxib (Vioxx) on COX-2 versus COX-1 was compared with that of commonly used nonsteroidal anti-inflammatory drugs (NSAIDs) in 76 healthy volunteers randomized to placebo, rofecoxib 12.5 mg qd, rofecoxib 25 mg qd, diclofenac 50 mg tid, ibuprofen 800 mg tid, sodium naproxen 550 mg bid, or meloxicam 15 mg qd. All of these doses include the high end of the approved clinical dose range. Ex vivo whole-blood assays were used to determine the effect on COX-2 and COX-1 activity, respectively. Urinary prostanoids were also measured. Mean inhibition of COX-2 (measured as the weighted average inhibition [WAI] of lipopolysaccharide [LPS]-induced PGE2 generation over 8 hours on day 6 vs. baseline) was -2.4%, 66.7%, 69.2%, 77.5%, 93.9%, 71.4%, and 71.5% for placebo, rofecoxib 12.5 mg, rofecoxib 25 mg, meloxicam, diclofenac, ibuprofen, and naproxen, respectively. Corresponding values for mean inhibition of COX-1 (measured as TXB2 generation in clotting whole blood) were -5.15%, 7.98%, 6.65%, 53.3%, 49.5%, 88.7%, and 94.9%. Rofecoxib had no significant effect on urinary excretion of 11-dehydro TXB2, a COX-1-derived product. These data support the contention that rofecoxib is the only drug of the regimens tested that uniquely inhibits COX-2 without affecting COX-1.

Effect of montelukast on the pharmacokinetics and pharmacodynamics of warfarin in healthy volunteers

Montelukast, a cysteinyl leukotriene receptor antagonist, is being developed for the treatment of asthma and related diseases. This study was designed to evaluate whether montelukast at clinically used dosage levels would interfere with the anticoagulant effect of warfarin. In a two-period, double-blind, randomized crossover study, 12 healthy male subjects received a single oral dose of 30 mg warfarin on the 7th day of a 12-day treatment with montelukast, 10 mg daily by mouth, or a placebo. Montelukast had no significant effect on the area under the plasma concentration-time curves and peak plasma concentrations of either R- or S-warfarin. However, slight but statistically significant decreases in time to peak concentration of both warfarin enantiomers and in elimination half-life of the less potent R-warfarin were observed in the presence of montelukast. These changes were not considered as clinically relevant. Montelukast had no significant effect on the anticoagulant effect of warfarin, as assessed by the international normalized ratio (INR) for prothrombin time (AUC0-144 and INR maximum). The results of this study suggest that a clinically important interaction between these drugs is unlikely to occur in patients requiring concomitant administration of both drugs.

Retrieval of undeployed intracoronary Palmaz-Schatz stents

Two patients undergoing stent placement with the Palmaz-Schatz coronary stent delivery system experienced intracoronary stent embolization. Using a two-wire technique, the stents were successfully removed from the coronary circulation, and this allowed completion of the percutaneous revascularization procedure without any clinical sequelae. These two cases represent the first report of successful percutaneous retrieval of undeployed, retained intracoronary Palmaz-Schatz stents.

Clinical application of a new Palmaz-Schatz coronary stent delivery system with a short (8 mm) nonarticulated stent

The standard Palmaz-Schatz coronary stent delivery system (SDS), with a 15 mm articulated stent and a 5F protective sheath, is relatively rigid and high in profile. Its use is contraindicated in vessels where there is severe tortuosity proximal to or in the lesion itself. Recently a new SDS, with a short (8 mm) nonarticulated stent, has become available. We present three patients with complex coronary anatomy solved with this new SDS. The first patient had a distal stenosis in an extremely tortuous and diffusely diseased right coronary artery (RCA). The second patient had a severe proximal RCA stenosis occurring at a bend of more than 90 degrees. The third patient had a very long stenosis of the left anterior descending coronary artery involving the ostium, requiring multiple tandem stenting. The availability of this short stent will greatly expand the clinical application of intracoronary stenting to patients with complex coronary anatomy.

Intracoronary stenting in acute myocardial infarction

Stent implantation into an infarct-related artery during acute myocardial infarction is generally contraindicated because of the risk of stent thrombosis. We report on 3 patients who had successful stenting for an acute occlusive dissection that developed during direct infarct coronary angioplasty and was refractory to conventional prolonged balloon dilatation, with good long-term clinical and angiographic results. The prerequisites for success include proper premedication, presence of only a minimal amount of thrombus in the infarct-related artery, liberal use of intracoronary thrombolytic therapy, as perfect an angiographic result as possible, as well as careful and aggressive post-stenting anticoagulation.

Two years experience with the Palmaz-Schatz coronary stent in a heterogeneous patient population

Between January 1991 and December 1992, 136 Palmaz-Schatz coronary stents were implanted in 113 native coronary arteries in 106 patients. Forty-seven patients presented with stable angina, 50 with unstable angina, 7 with congestive cardiac failure and unstable angina and 2 were asymptomatic. Stenting was carried out in 15 patients for restenosis after coronary angioplasty (PTCA), 32 for significant dissection during PTCA (with 19 acute and 13 threatened closure), 10 for suboptimal PTCA results and 56 for de novo lesions, 52 (92.9%) of which were either ACC/AHA type B or C. Successful delivery was achieved in 97.2% (103/106) of patients or 97.3% (110/113) of vessels. Percent diameter stenosis was reduced from 78 +/- 13% to 4 +/- 11%. There were two subacute stent thromboses (1.9%), resulting in Q-Wave myocardial infarction. Three deaths (2.9%) occurred, all from the group with congestive cardiac failure and unstable angina. Major bleeding/vascular complications occurred in 4 patients (3.9%). All patients were followed up for a mean of 18 months (6 months to 30 months). Eighty-five patients were asymptomatic. Three patients were angina-free but continued to have, albeit improved, congestive cardiac failure. Ten patients had recurrence of angina, all within 6 months of the stenting procedure. Four were treated medically and 4 had PTCA of whom one eventually had coronary bypass surgery. Two patients had new lesions, successfully treated by PTCA or stenting. In conclusion, a high rate of successful delivery of the Palmaz-Schatz coronary stent can be achieved in a wide spectrum of patients with few complications which are mostly related to anticoagulation. It offers very effective bailout for acute closure during PTCA. Despite the presence of unfavorable pre-procedure patient and lesion characteristics, the acute and long term clinical results are encouraging.

Study on the health hazards of scrap metal cutters

Scrap metal cutters seemed to be left out in most preventive programmes as the workers were mainly contract workers. The health hazards of scrap metal cutting in 54 workers from a foundry and a ship breaking plant were evaluated. Environmental sampling showed lead levels ranging from 0.02 to 0.57 mg/m3 (threshold limit values is 0.15 mg/m3). Exposure to lead came mainly from the paint coat of the metals cut. Metal fume fever was not reported although their main complaints were cough and rhinitis. Skin burns at all stages of healing and residual scars were seen over hands, forearms and thighs. 96% of the cutters had blood lead levels exceeding 40 micrograms/100 ml with 10 workers exceeding 70 micrograms/100 ml. None had clinical evidence of lead poisoning. The study showed that scrap metal cutting is a hazardous industry associated with significant lead exposure. With proper medical supervision, the blood lead levels of this group of workers decreased illustrating the importance of identifying the hazard and implementing appropriate medical surveillance programmes.

Recurrent meningitis of 5 years duration due to Cryptococcus neoformans

A patient with recurrent meningitis over five and a half years due to Cryptococcus neoformans is reported. The relapsing course and the unusual diagnostic features are emphasized.

Chromate allergy: total chromium and hexavalent chromate in the air

This is a study on atmospheric concentration of total chromium and hexavalent chromate and its role in chromate sensitivity. Air concentration of total chromium and hexavalent chromate in a construction factory, a busy city area, a suburban area, a residential area, and a heavy industrial area were measured by air sampling pumps. Hexavalent chromate was not detected in any sampled areas. Two (concreting areas) of 8 locations in the construction factory had total chromium of 0.2 and 2.3 micrograms/m3 in the atmosphere. It appeared that the atmospheric concentration of total chromium and hexavalent chromate was negligible. These findings indicate that unexplained chromate sensitivity, as so often seen in patients attending a contact dermatitis clinic, is not attributable to exposure to hexavalent chromate in the air.

Percutaneous transfemoral catheterization in aortic stenosis with a USCI Sones catheter curve A type 1 (7540)

We report our experience with the use of a USCI Sones catheter curve A type 1 (7540) to cross the aortic valves of 45 patients with clinically significant aortic stenosis. The technique was successful in all our patients with a fluoroscopic time of less than 3 min. A gradient of up to 200 mmHg across the aortic valve area was recorded, and the smallest valve area calculated was less than 0.2 cm2. The method obviated the need for a guidewire and satisfactory left ventriculograms were obtained. No major complication was observed. We conclude that the technique is a simple, rapid, and safe means of obtaining left ventricular hemodynamic and angiographic information in patients with aortic stenosis of various degrees of severity.

Familial occurrence of mitral valve prolapse: is this related to the straight back syndrome?

Familial prevalence of mitral valve prolapse in a Chinese population was determined in 22 propositi of whom 10 had straight back (group A), three had abnormally high metacarpal index (group B), and nine had neither (group C). Of 71 (32 male and 39 female subjects) first degree relatives screened, mitral valve prolapse was found in 19 (seven male and 12 female subjects) (26.8%). The familial prevalence among groups A, B, and C was 20%, 30%, and 38.5%, respectively. Our study indicates that the familial occurrence of mitral valve prolapse does not depend on its association with the straight back syndrome.

The first documented outbreak of trichinellosis in Hong Kong Chinese

An outbreak of trichinellosis occurred in a Chinese family after the ingestion of inadequately cooked pork. Diagnosis was established by the demonstration of antibodies against Trichinella spiralis larval antigen by crossed immunoelectrophoresis and enzyme-linked immunosorbent assays, and living larvae in muscle biopsy. The main presenting symptom of these patients was pyrexia. Typical clinical features of Trichinella infection such as periorbital edema and severe myalgia were either minimal or absent. A history of having eaten insufficiently cooked meat is thus extremely important for correct diagnosis. We believe that this is the first documented report of a Trichinella outbreak in Chinese living in Hong Kong.

Right aortic arch and Kommerell's diverticulum

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Acute intravascular hemolysis indicating thrombosis of Bjork-Shiley aortic prosthesis

A patient with a Bjork-Shiley aortic prosthesis inserted two years and four months prior to receiving adequate anticoagulant therapy suddenly had severe intravascular hemolysis develop as a result of thrombosis of her aortic prosthesis. There was no notable hemodynamic compromise. The mechanism of the intravascular hemolysis is discussed.

Intravenous ranitidine has no hemodynamic effects in subjects with normal lung function and patients with chronic obstructive airway disease

Ten patients with Chronic Obstructive Airway Disease (COAD) and five subjects with duodenal ulcers and normal lung function were given 50 mg ranitidine as a single intravenous bolus injection. Hemodynamic responses were continuously monitored. There were no significant alterations in systemic and pulmonary pressures, systemic and total pulmonary vascular resistances or cardiac output. Continuous ECG recordings did not reveal arrhythmias. Ranitidine does not appear to cause any significant disturbance of hemodynamic function in COAD patients. This contrasts with alterations in hemodynamics previously observed following administration of cimetidine.

Skeletal abnormalities in mitral-valve prolapse

One hundred and fifteen Chinese patients with mitral-valve prolapse were evaluated for skeletal abnormalities, to determine their prevalence and interrelation. Measurements of thoracic dimensions from radiographs differed significantly from the normal population. The commonest thoracic abnormality was the straight back, being present in 37.5% of the male and 26.9% of the female patients. Accurate quantitation of thoracic kyphosis was difficult. Either the ratio between antero-posterior and transverse thoracic diameters or a vertebral index characterised the straight back. Other abnormalities included scoliosis, sternal and rib deformities. The mean of metacarpal indices for the patients was also significantly higher than the normal mean. An abnormal metacarpal index was present in 20.9%. There was dissociation between peripheral and thoracic skeletal abnormalities. The diagnostic, aetiological and prognostic implications of associated skeletal abnormalities were discussed.

Aortic catheterisation via percutaneous left ventricular puncture

When retrograde catheterisation and angiography of the ascending aorta from the brachial or femoral approach is not possible, this can be accomplished by direct percutaneous left ventricular puncture. The haemodynamic and angiographic information obtained was essential to surgical correction of aortic arch anomalies as illustrated in two patients.

Echocardiographic assessment of the Hall Kaster mitral prosthesis

To study the effect of the Hall Kaster prosthesis on left ventricular filling characteristics after mitral valve replacement, postoperative M-mode echocardiograms of the left ventricle from sixteen patients were digitized to determine the peak rate of dimension (D) increase of the left ventricle during diastole (peak dD/dt) and the rapid filling period (RFP). These were compared with fourteen normal controls, thirty patients with Starr Edwards and thirty patients with Bjork Shiley mitral prosthesis. Results suggest that the Hall Kaster mitral prosthesis is less obstructive than either the Starr Edwards or the Bjork Shiley prosthesis, and tends to approximate the normal mitral valve.

Is cardiac catheterisation necessary before valvular surgery?

The results of 269 patients who had undergone valvular operations during and 18-month period (January 1, 1980, to June 30, 1981) were analysed. One hundred and seventy-four patients referred for surgery had undergone routine cardiac catheterisation elsewhere, and these, together with four electively catheterised patients, constituted a group representing the conventional approach. Ninety-one patients were assessed only by clinical and non-invasive methods, including echocardiography, and were subjected to surgery without catheterisation. The two groups were comparable in their major clinical characteristics including age, sex ratio, functional class, previous history of closed mitral valvotomy, aetiology of valve lesions, and type of operative procedure performed. There was no discordance between operative finding and preoperative assessment, except in two patients of the catheterised group. Hospital mortality was acceptably low and was comparable between the two groups. Cardiac catheterisation is, thus, no longer necessary in the majority of patients undergoing surgery for valvular heart diseases.

Mitral valve prolapse and pre-excitation

Two out of 118 patients with mitral valve prolapse were found to have pre-excitation. The presence of mitral valve prolapse in one patient with Lown-Ganong-Levine syndrome and the persistence of prolapse in the presence and absence of pre-excitation in another patient with intermittent type B Wolff-Parkinson-White syndrome suggest that mitral valve prolapse in pre-excitation syndrome may not be secondary to the abnormal activation pattern of the left ventricle, which has been suggested as a possible mechanism by some investigators.

Percutaneous left ventricular angiography

Recurrence of persistence of heart failure in patients after mitral and aortic valve replacement is a difficult diagnostic problem. Clinical evaluation and noninvasive tests cannot always distinguish poor left ventricular function from paraprosthetic leak or persistent pulmonary vascular disease. Full evaluation by cardiac catheterisation may then be necessary but is difficult because of the inaccessibility of the left ventricle. Under these circumstances, left ventriculography by direct transapical puncture is an alternative to crossing the prosthesis by a catheter and may be the only way of obtaining diagnostic information. We describe our experience of left ventriculography by percutaneous transapical passage of a flexible angiographic catheter (as distinct from a rigid angiographic needle) in 15 such patients (on 16 occasions). Non-fatal complications occurred in three patients. The information thus obtained allowed a clinical decision to be made and distinguished the inoperable from the operable group. Surgery was subsequently performed in seven patients with beneficial results.