Performance of a new transdermal nitroglycerin adhesive patch formulation

This two-period crossover study in 24 healthy men compared the transdermal absorption of nitroglycerin from a new 20-cm2 nitroglycerin adhesive transdermal patch applied for a single 24-hour period (q24hr) with that from one inch of 2% nitroglycerin ointment applied over a 50-cm2 area every eight hours (q8hr) during a single 24-hour period. The observed differences in pharmacokinetic parameters were expected, based on product design (q24hr vs q8hr) and surface area (20 cm2 vs 50 cm2); however, when corrected for surface area, the mean plasma AUC ratios indicated that the patch delivered about 1.5 times more drug than the ointment. The patch delivery of nitroglycerin was confirmed by patch residual results, which indicated nitroglycerin was released at a rate of 0.75 mg/cm2/24 hrs. The patch exhibited good skin adhesion throughout the 24-hour application period.

Preparation and characterization of monoclonal antibody specific for alpha-bungarotoxin and localization of the epitope

We prepared a monoclonal antibody (mAb) specific for alpha-bungarotoxin (alpha-BuTX) which can neutralize the lethal toxicity of the toxin and inhibit the binding of [3H]-alpha-BuTX to the nicotinic acetylcholine receptor. The radiolabelled toxin has a high affinity for the mAb. alpha-BuTX was digested with acid protease A and the resulting peptide fragments were isolated by reverse-phase HPLC. The epitope recognized by the mAb has been localized on the basis of competition radioimmunoassay between [3H]-alpha-BuTX and the peptide fragments of alpha-BuTX towards the antibody. The epitope specific for the mAb may be located in the second loop of alpha-BuTX, probably involving residues 34-41.

Pharmacokinetics of flecainide in patients with cirrhosis of the liver

The pharmacokinetics of flecainide were studied in six patients with cirrhosis of the liver and in six healthy subjects after a single 2 mg/kg intravenous dose. Hepatic biotransformation capability before flecainide dosing was assessed by antipyrine challenge. The mean plasma antipyrine t1/2 for patients (42.2 hours) was longer (p less than 0.01) than that for subjects (11.7 hours). For control subjects, the plasma t1/2 of flecainide (9.5 hours) was shorter (p less than 0.01), plasma clearance (9.1 ml/min/kg) was faster (p less than 0.01), and volume of distribution (7.5 L/kg) was smaller (p less than 0.05) compared with corresponding values in patients. Renal clearance did not differ (p greater than 0.05) between the two groups. The mean ratio of renal clearance to plasma clearance for subjects (0.4) was smaller (p less than 0.05) than that for patients. The slower rate of flecainide elimination from plasma in patients is likely due to reduced hepatic biotransformation. In patients with cirrhosis, plasma levels of flecainide may accumulate to unacceptably high levels with usual dosage regimens.

Pharmacokinetics and bioavailability of hydromorphone: effect of various routes of administration

The pharmacokinetics and bioavailability of hydromorphone following various routes of administration, i.e., intravenous, oral, intranasal, and transdermal, were investigated in rabbits. Hydromorphone plasma concentrations were determined by reverse-phase high-performance liquid chromatography (HPLC). Comparison of area under the concentration versus time curve (AUC) between intravenous and oral administrations showed a low bioavailability of hydromorphone after oral administration. The nasal absorption of hydromorphone was studied by the in situ nasal recirculation technique, and the results showed that hydromorphone is well absorbed from the nasal mucosa. The transdermal permeation of hydromorphone was also evaluated for 24 hr and a steady-state plasma concentration (0.135 micrograms/ml) was achieved during the 6- to 24-hr periods following the application of a transdermal patch on the inner pinna of the rabbit's ear.

Urethane-acepromazine: a novel method of administering parenteral anesthesia in the rabbit

Stable long-term anesthesia in the rabbit (greater than 8 hr) has been achieved by the administration of urethane and acepromazine. Twenty-five healthy male New Zealand white rabbits weighing 2 to 4 kg were used for this study. Two groups of animals were studied. The first group of 11 rabbits received urethane (1.0 g/kg) and acepromazine (1 mg/0.46 kg). This resulted in stable light plane anesthesia for 13.5 +/- 4.5 hr (mean + S.D.). The second group of 14 rabbits received urethane (1.3 g/kg) and acepromazine (1 mg/0.46 kg) which resulted in deep plane anesthesia for 23.0 +/- 4 hr. Heart rate and respiratory rate remained stable throughout the entire period and all animals were alert and without any observable side effects by 48 +/- 3 hr. This study indicates that the combination of urethane-acepromazine is a safe and reproducible parenteral anesthetic that may be used in studies of long duration in rabbits.

The effect of flecainide acetate, a new antiarrhythmic, on plasma digoxin levels

The possible effect of oral flecainide acetate on steady-state digoxin levels was assessed in 15 healthy men. Each volunteer received digoxin 0.25 mg daily (8 AM) for 22 consecutive days and flecainide 200 mg bid (8 AM and 8 PM) on days 11 through 15. Plasma digoxin and flecainide levels were measured by radioimmunoassay and gas-liquid chromatography methods, respectively. Flecainide levels were within the range associated with suppression of premature ventricular contractions in patients. Mean plasma digoxin levels just before the 8 AM dose were 0.46 ng/mL on days 9 and 10 (baseline), 0.57 ng/mL (P less than .05) on day 13, and 0.49 ng/mL (not significant [NS]) on day 15. Compared with a mean six-hour postdose baseline digoxin level of 0.58 ng/mL, postdose levels were 0.62 ng/mL (NS) and 0.65 ng/mL (P less than .05) on days 13 and 15, respectively. On an average for each subject, predose and six-hour postdose digoxin levels increased by 24 +/- 35% and 13 +/- 19%, respectively, during coadministration. The changes in electrocardiographic intervals and vital signs that occurred during concomitant drug administration were not clinically significant although a slight prolongation of the PR interval was noted in some subjects. Unless plasma digoxin levels are in the upper end of the therapeutic range, changes in magnitude as observed in this study should be clinically inconsequential for most patients.

Theophylline and dyphylline pharmacokinetics in the horse

The pharmacokinetics of theophylline and dyphylline were determined after IV administration in horses. In a preliminary experiment, the usual human dosage (milligram per kilogram) of each drug was given to 1 horse. Results were used to calculate dosages for a cross-over study, using 6 horses for each drug. Theophylline plasma concentrations decreased triexponentially in 5 of 6 healthy horses after IV infusion of 10 mg of aminophylline/kg of body weight for 16 to 32 minutes. In the 6 horses, total body elimination rate constants were variable, and the half-life of theophylline was 9.7 to 19.3 hours. Clearance was 42.3 to 69.2 ml/hr/kg. The initial distribution phase was rapid (t1/2 approx 3.5 to 4 minutes); a 2nd distribution phase was slower (t1/2 approx 1.5 to 2 hours). Plasma concentrations of theophylline were in the assumed effective range (10 to 20 micrograms/ml) from 15 minutes until 40 minutes after time zero. The mean apparent volume of distribution was 1.02 L/kg. After bolus IV injection of dyphylline (20 mg/kg), pharmacokinetics were best described by a 2-compartment open model in 2 horses and by a 3-compartment open model in 4 horses. In the 6 horses, elimination half-life of dyphylline was 1.9 to 2.9 hours, and clearance was 200 to 320 ml/hr/kg. Plasma concentrations (approx 50 micrograms/ml) were observed at 10 minutes after injection without adverse effects. Concentrations greater than 10 micrograms/ml were observed from time zero to about 1.5 hours after injection. Theophylline induced significant increases in heart rate, but dyphylline did not affect heart rate significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of salsalate (nonacetylated salicylate) and aspirin on serum prostaglandins in humans

Prostaglandin E2 (PGE2), thromboxane B2 (TXB2), and salicylic acid were measured in blood samples from 10 healthy men after administration of antiinflammatory doses of aspirin (3.9 g/day) or salsalate (3.0 g/day). Each medication was given for 3 days, followed by an observation period of 13 days. Plasma salicylate concentrations were slightly, but generally insignificantly, higher during aspirin dosing, although both drugs produced salicylic acid levels in the antiinflammatory range. Serum levels of PGE2 and TXB2, which reflected synthesis of cyclo-oxygenase products by platelets, were minimally affected by salsalate but profoundly suppressed by aspirin. When medication was discontinued, the effects of salsalate on serum PGE2 and TXB2 were readily reversible within 36 h, whereas the recovery from aspirin was still incomplete after 13 days of observation. These results indicate that the two orally administered salicylates have differential effects on prostaglandin synthesis in platelets and may also differ in their therapeutic and adverse effects.

Analysis of cheese for histamine, tyramine, tryptamine, histidine, tyrosine, and tryptophane

A method is described for determining the content of selected biologically active amines (histamine, tyramine, tryptamine) and amino acids (histidine, tyrosine, tryptophane) in cheeses by high performance liquid chromatography. The amines and amino acids were quantified by employing a counter ion-containing mobile phase and by comparing peak areas of high performance liquid chromatography charts for sample cheeses versus standard cheeses containing known amounts of added amines based on dual injections of samples and standards. Recovery of amines and amino acids varied from 87.5 to 111%. Histamine, which has been associated with food poisoning in concentrations of 185 mg/100 g in Swiss cheese and 180 to 500 mg/100 g in fish, was found in concentrations above 500 mg/100 g in Swiss cheese. The high performance liquid chromatography analytical method should be useful for screening to detect cheese samples containing toxic amounts of histamine and for research studies designed to determine the cause and effect relationships for histamine production in cheese.

High-performance liquid chromatographic method for the quantitation of a meta-O-dealkylated metabolite of flecainide acetate, a new antiarrhythmic

A simple, sensitive and selective high-performance liquid chromatographic method has been developed to analyze meta-O-dealkylated flecainide, a major metabolite of flecainide acetate, in human biological fluids. Sample preparation is accomplished through the use of bonded-phase extraction columns and the samples are chromatographed on a reversed-phase system with fluorescence detection. An external calibration method is used for quantitation and the inter-day and intra-day precision and accuracy are good. The method has been used to determine metabolite levels in samples from healthy subjects and patients with arrhythmias or renal impairment.

Quantitation of flecainide acetate, a new antiarrhythmic agent, in biological fluids by gas chromatography with electron-capture detection

A sensitive and selective gas chromatographic (GC) method for the quantitation of flecainide acetate, a new antiarrhythmic agent, was developed. The unchanged drug and internal standard were separated from biological fluids by a sequence of solvent extractions and then the drug was derivatized. The pentafluorobenzamide derivatives were chromatographed on a 3% SP-2250 glass column and detected with a nickel-63 electron-capture detector. By this method, greater than or equal to 12.5 ng of flecainide/mL can be quantitated in a 1-mL sample of plasma, saliva, or urine. The intraday precision, expressed as the RSD, at plasma levels of 12.5, 25, 50, 100, 200, 300, 400, and 600 ng/mL was 3.4, 6.2, 5.3, 6.4, 1.0, 1.6, 2.0, and 0.5%, respectively; the accuracy, expressed as relative error at these levels was -24.6, -6.9, -6.0, +0.6, +3.8, -0.3, +2.4, and -1.4%, respectively. The interday precision at these levels was 13.8, 13.0, 5.7, 7.6, 8.3, 6.1, 9.0, and 5.4%, respectively. Several other antiarrhythmic agents and one beta-blocker, which might be administered concurrently with flecainide acetate, do not interfere with the assay.

Biotransformation and elimination of 14C-flecainide acetate in humans

The metabolism of 14C-flecainide acetate, a new antiarrhythmic, was investigated in four healthy human subjects, after a single, 200-mg oral dose. The cumulative recovery of radioactivity ranged from 81 to 90% (mean, 86%) in urine and from 4 to 6% (mean, 5%) in feces; thus, flecainide does not appear to undergo extensive biliary excretion, unless reabsorption occurs after biliary elimination. The cumulative excretion in urine of unchanged flecainide ranged from 35 to 50% (mean, 42%) of the dose and was essentially complete by 72 hr postdose. Peak plasma levels of radioactivity (524 to 848 ng eq/ml) and of unchanged flecainide (214 to 281 ng/ml) were attained at 2 to 3 hr postdose. The average half-life for the disappearance of unchanged flecainide from plasma was about 16 hr; disappearance of total metabolites from plasma was only slightly slower. Radiomonitored TLC analysis showed that urine contained two major metabolites and two or three minor ones; both major metabolites were extensively conjugated. By TLC, NMR, and mass spectral comparisons to reference compounds, the two major urinary metabolites were shown to be meta-O-dealkylated flecainide and the meta-O-dealkylated lactam of flecainide. Most of the radioactivity in urine was accounted for by flecainide and the two major metabolites.

Application of a bonded-phase extraction column for rapid sample preparation of flecainide from human plasma for high-performance liquid chromatographic analysis--fluorescence or ultraviolet detection

A simple, rapid, selective, and sensitive procedure for the monitoring of flecainide levels in human plasma is described. The drug and the internal standard--a positional isomer of flecainide--are separated from plasma by the use of a disposable extraction column packed with reversed-phase sorbent. The drug and internal standard which are selectively retained on the extraction column are eluted. An aliquot is injected onto a mu-Bondapak phenyl column and eluted with a mixture of acetonitrile and 0.06% phosphoric acid (40:60, vol/vol) at a flow rate of 2 ml/min. The eluted drug and internal standard are measured by a fluorescence detector with excitation and emission wavelengths of 300 and 370 nm, respectively. The linear range is 3-2,000 ng/ml, and the sensitivity limit is 3 ng/ml with 1 ml of plasma. The within-day coefficient of variation was 1.1-4.6% at concentrations ranging from 3 to 1,600 ng/ml. Many drugs given concomitantly with flecainide acetate do not interfere with the assay. The method compares favorably to a well-documented gas-liquid chromatographic method and is suitable for use in plasma drug level monitoring for patient management as well as in pharmacokinetic studies. Similar results were obtained using an alternate detection method (ultraviolet detection at 298 nm).

Analysis of theophylline by automated multidimensional high-performance liquid chromatography involving direct plasma injection

A procedure of direct injection of whole plasma for the analysis of theophylline by an automated multidimensional high-performance liquid chromatographic (HPLC) technique is described. The procedure requires as little as 30 microliters of plasma sample and has a linear range of 0.25-30 micrograms/ml. Unknown plasma samples, after the addition of internal standard, are directly injected into the HPLC system. The chromatographic procedure is fully automated, thus the attention and time required from the analyst is reduced to a minimum. About 70 samples can be analyzed per day with approximately 3 hr of analyst time.

High-performance liquid chromatographic method for the quantitation of flecainide, a new antiarrhythmic, in human plasma and urine

A simple, selective, sensitive, and accurate high-performance liquid chromatographic method for the quantitation of flecainide in human plasma and urine is described. The method is based on initially washing the sample with hexane followed by a single extraction with hexane. The extracted drug and internal standard are chromatographed on a Zorbax TMS column with a mobile phase consisting of acetonitrile-1% acetic acid in 0.01 M pentanesulfonate (45:55, v/v). The eluent is monitored at 308 nm. This method can routinely quantitate plasma or urine flecainide concentrations as low as 22 ng/ml with a 1-ml sample and 11 ng/ml with a 2-ml sample with no interference from endogenous substances and many drugs and their metabolites. The standard curve is linear over a concentration range of 22-1746 ng/ml. The precision and accuracy of the described method are suitable for monitoring flecainide levels in therapeutic, tolerance, and pharmacokinetic studies in humans.

Quantitative determination of nefopam in human plasma, saliva and cerebrospinal fluid by gas-liquid chromatography using a nitrogen-selective detector

A sensitive and selective gas-liquid chromatographic method for the determination of nefopam in human plasma, saliva and cerebrospinal fluid has been developed. The method includes the selective extraction of nefopam and the internal standard, orphenadrine, from biological fluids by a double extraction procedure. The extracted nefopam and internal standard are analyzed by a gas chromatograph equipped with a 3% OV-17 glass column and a nitrogen-phosphorus flame ionization detector (NPFID) operated in the nitrogen mode. The detector provides the needed high sensitivity and also selectivity due to the inherent characteristics of NPFID to discriminate against non-nitrogen containing materials. Five nanograms nefopam per ml plasma or saliva are routinely quantitated with a 1-ml sample or as little as 2 ng per ml cerebrospinal fluid with a 3-ml sample. The intra-day reproducibilities, expressed as the relative standard deviation, are 5, 2 and 3% at 10, 35 and 75 ng/ml plasma levels, respectively. The accuracies expressed by relative error at these levels are 12, -4 and -2%, respectively. The inter-day reproducibility is demonstrated by the small relative standard, deviation, 2%, of the slopes from ten plasma standard curves run on ten different days. In various clinical studies in humans the method has been successfully applied to the study of single-dose pharmacokinetics of nefopam and the monitoring of nefopam concentrations in saliva and cerebrospinal fluids.

Oral flecainide acetate for the treatment of ventricular arrhythmias

The antiarrhythmic efficacy and safety of oral flecainide acetate were assessed during a controlled, short-term dosage-maintenance study. Thirteen patients with chronic ventricular ectopy entered a placebo control period, and 11 with persistent, frequent (greater than 600 per 12 hours) premature ventricular complexes (PVCs) advanced to drug therapy. Of 10 patients completing a trial of different doses, nine responded completely, with a mean PVC suppression of 98,3 per cent. Repetitive PVCs were eliminated. The mean effective dose was 189 mg per 12 hours, and the effective plasma concentration before administration of a dose averaged 635 ng per milliliter. One patient responded partially (68 per cent of PVCs suppressed). Flecainide continued to be effective and well tolerated at the end of a two-week outpatient trial in the nine complete responders, maintaining an average PVC suppression of 94.6 per cent. The PR and QRS intervals were mildly prolonged. The echocardiographic ejection fraction was unchanged during treatment. The elimination half-life was long - 18.8 +/- 3.8 hours. Flecainide thus appears to be a highly effective and well-tolerated antiarrhythmic agent with favorable pharmacokinetics.

Pear-shaped bladder caused by large iliopsoas muscles

A case of pear-shaped bladder resembling pelvic lipomatosis was shown to be caused by large iliacus and psoas muscles.

Borderlands in the diagnosis of regional enteritis: trends in overdiagnosis and value of therapeutic trial

Our regional experience in the state of Connecticut indicates that Crohn's disease is being overdiagnosed. Six patients with disorders mimicking regional enteritis are presented, one of whom had an atypical clinical course and the remainder had atypical therapeutic responses. The radiologist should be aware of clinical responses and make reassessments if necessary, in order not to overlook surgically treatable conditions.

The protean gastrointestinal manifestations of metastatic breast carcinoma

Metastatic breast carcinoma commonly remains silent for many years following initial diagnosis and mastectomy, and then appears as metastases at various locations. Gastrointestinal involvement is not uncommon and includes any site along the whole length of the gut, the liver, and the biliary tree; it occasionally simulates other diseases and causes difficulty in diagnosis. The radiographic features and differential diagnoses are discussed.

Determination of an anti-inflammatory methanesulfonanilide in plasma by high-speed liquid chromatography

A sensitive and chemically specific high-speed liquid chromatographic method was developed for the determination of 4-nitro 2-phenoxymethanesulfonanilide in plasma. The method includes selective extraction of the anti-inflammatory drug and an internal standard, 2-(4'-chlorophenoxy)-4-nitromethanesulfonanilide, into benzene from acidified plasma followed by reextraction into 0.2 N NaOH. The aqueous layer is acidified, and the drug is reextracted into benzene. The benzene is evaporated, and the residue is dissolved in a small volume of acetonitrile. A 10-microliter aliquot is analyzed on a reversed-phase column. The mean overall extraction recovery, after correction for aliquot factors, is 99%. The accuracy, expressed as the relative error, is 4, 0.3, and -3% at 0.60, 1.50, and 3.00 microgram/ml, respectively. Repeated analysis of reference standards indicates that the precision, expressed as the relative standard deviation, is 3% or less. The lower sensitivity limit is 0.2 microgram/ml with a 2-ml plasma sample. The method was applied successfully to the determination of plasma levels of 4-nitro-2-phenoxymethanesulfonanilide in humans and rats in metabolic experiments at pharmacological doses.

Studies on shigella isolated in southern Taiwan

During 1969, a total of 1,476 fecal and rectal swab specimens was collected from children with diarrhea and 249 strains of shigella were isolated. The incidence was 16.9%. The serotypes of 249 strains were: Shigella dysenteriae, 1.6% (4 strains); S. flexneri, 73.1% (182 strains); S. boydii, 3.2 (8 strains) and S. sonnei, 22.1% (55 strains). There was no marked difference of the isolation rate throughout the whole year. The susceptibility of shigella isolates to chemotherapeutic agents were also investigated. The percentage of the strains susceptible to gentamicin was 97.2%; to cephaloridine, 93.2%; to kanamycin, 91.9%; to colistin, 91.6%; to hetacillin, 88.4%; to ampicillin, 82.4% and to nalidixic acid, 79.9%. The other tested chemotherapeutic agents were less effective.

Loss of colonic haustration in progressive systemic sclerosis

Complete loss of colonic haustration was observed in six cases of progressive systemic sclerosis. Varying degrees of haustral loss or sacculation were noted in twelve others. An increase in colonic length was characteristic and, occasionally, there was slight to moderate generalized dilatation. Correlation of these findings with the microscopic appearance of the colon showed that muscular atrophy and fibrous replacement were consistent findings, varying in degree. Although the data are insufficient to permit definite conclusions, it is suggested that these changes may be responsible for colonic lengthening and loss of haustration. Attention is drawn to the importance of not confusing this appearance with other conditions, particularly chronic ulcerative colitis.

The wandering gallbladder

An unusual case of a hypermobile gallbladder and liver is presented. The liver and gallbladder, supported only by a long midline falciform ligament, rotated freely from the right to the left upper quadrant. Because of a long gastrohepatic ligament and mesocolon, intermittent volvulus of the stomach and colon were associated findings.