When is a phaeo not a phaeo? Depression in an adolescent leading to a phaeochromocytoma-like biochemical profile

A pheochromocytoma was suspected in a 14 year old boy. Elevated urinary and plasma catecholamines as well as clonidine test were consistent with the diagnosis. However, imaging studies were negative, and biochemical abnormalities normalized with treatment of concomitant depression. It is important to consider an array of confounders, including psychiatric conditions, when testing for pheochromocytoma.

[Analysis of clonidine in biological fluids using gas chromatography with an electron capture detector]

The method of clonidine identification in blood and urine is described. It is based on liquid-liquid extraction and purification with toluol, subsequent derivation with pentafluobenzoylchloride and test on gas chromatograph with a detector of electron capture. The method is proposed for expert examinations.

Munchausen syndrome by proxy (MSBP): an extreme form of child abuse with a special forensic challenge

Munchausen syndrome by proxy (MSBP) is a special form of child abuse in which an adult repeatedly produces symptoms of illness in a person under his/her care. In most cases the perpetrators are mothers who repeatedly and in different ways produce or feign symptoms of illness in their children in order to obtain medical treatment for them. MSBP is thus a special form of child abuse that is also of importance in the field of forensic medicine and a particular challenge to the medicolegal expert. We report two cases of poisoning with different substances (clozapine and clonidine) detected by toxicological investigations at our Department of Legal Medicine. The relevance of the problem for the medicolegal expert and the importance of an interdisciplinary co-operation are pointed out.

Isotachophoretic determination of bisoprolol, clonidine, disopyramide and tolazoline in human fluids

Separation and determination of bisoprolol, clonidine, disopyramide and tolazoline in control serum and in human urine was investigated by capillary isotachophoresis. The drugs were separated by using the cationic electrolyte system. viz., sodium acetate buffer (pH 4.64) (c1 = 10 mM)-beta-alanine. The compounds were almost totally isolated from serum by solid-phase extraction using a Sep-Pak C18 cartridge. The recovery of compounds varied from 87 to 99%. The linear calibration range was studied to apply the method to real human fluids. The limit of determination of the drugs was 40.0 micrograms/ml serum. The limit of determination by direct sampling for bisoprolol is 3 micrograms/ml urine.

Radioimmunoassay for clonidine in human plasma and urine using a solid phase second antibody separation

A reliable, sensitive, and specific radioimmunoassay (RIA) procedure for the quantitation of clonidine in plasma and other biological fluids was developed. The detection limit of the assay is 2 pg based on a 200 microliters sample. Nine commonly used drugs were found not to interfere with the RIA. The utility of the assay was demonstrated in a bioavailability study of clonidine conducted with 24 healthy subjects. Clonidine was readily quantitated in plasma over 4 half-lives. This assay is suitable for pharmacokinetic and bioavailability studies as well as therapeutic drug monitoring of patients.

Pharmacokinetics of transdermally delivered clonidine

We detail a series of pharmacokinetic investigations to determine the dose linearity, the effect of site of application, the duration of steady-state plasma concentrations, and the effect of chronic application when clonidine is administered transdermally. Dose linearity was assessed in six subjects with normotension after application of increasing sizes of transdermal clonidine systems (3.5, 7.0, and 10.5 cm2 size) to the upper outer arm. Of the six subjects studied, five had linear relationships between clonidine plasma concentrations at steady state and system size of greater than 0.975; in the sixth subject the correlation was greater than 0.90. The mean steady-state plasma concentrations with 3.5, 7.0, and 10.5 cm2 systems were 0.39, 0.84, and 1.12 ng/ml, respectively. The influence of site and duration of application on the absorption of transdermal clonidine was studied in eight subjects with normotension by use of the 3.5 cm2 system. The mean steady-state plasma concentration over the time interval from 3 to 7 days after application to the arm or to the chest did not significantly differ. When a system was left on the chest or arm for a total of 11 days (4 days beyond the recommended time to change systems), the plasma concentrations of seven of eight subjects with application to the arm and of six of eight subjects with application to the chest remained constant through day 11. The influence of consecutive applications of 3.5 cm2 transdermal clonidine systems on steady-state plasma clonidine concentrations was also studied in eight subjects with normotension over an 11-day period.(ABSTRACT TRUNCATED AT 250 WORDS)

Biotransformation of lofexidine in humans

1. Concentrations of unchanged drug and patterns of radioactive components in urine have been determined by h.p.l.c. following single oral doses of [14C]lofexidine hydrochloride (0.32 mg) to six human subjects. 2. A mean of 12% of the administered dose was excreted in urine as unchanged lofexidine, but the wide range (5-20% dose) indicated significant intersubject variation in the extent of biotransformation. This drug would appear to be metabolized more extensively than the related anti-hypertensive agent, clonidine. 3. The principal metabolite of lofexidine was 2,6-dichlorophenol, which was apparently excreted in urine as two O-glucuronic acid conjugates. The same two metabolites were also the main 14C components circulating in plasma at peak 14C concn. Formation of the phenol from lofexidine probably involved direct O-dealkylation rather than stepwise degradation of the side-chain. 4. Patterns of 3H components in the urine of rats and dogs after oral administration of [3H]lofexidine hydrochloride (0.1 mg/kg) were generally similar to those in human urine.

Tissue pharmacokinetics of clonidine in rats

The antihypertensive drug clonidine exhibits nonlinear pharmacokinetics in man and rats after intravenous injection. In order to define the basis of this nonlinearity, tissue kinetics of clonidine in rats were determined at three dose levels. It was found that tissue concentrations of clonidine were linearly related to dose increases in most organs with the exception of the heart, suggesting that there was a limited binding capacity in this organ. The rate of disappearance of clonidine from most tissues was best described by a monoexponential curve with half-lives of 30 to 120 min. An exception was the stomach, and clonidine accumulated in this organ, probably due to a pH partitioning effect of this weak base. Renal clearance of clonidine in rats was also examined and found to decrease by approximately 40% when the dose was increased from 50 microgram/kg to 250 microgram/kg. It was concluded that renal clearance and and possibly fecal clearance could explain the nonlinear pharmacokinetics of clonidine.

The measurement of clonidine in human plasma and urine by combined gas chromatography mass spectrometry with ammonia chemical ionization

The dimethyl derivatives of clonidine and [2H4]clonidine give good chemical ionization mass spectra when ammonia is used as reagent gas. A gas chromatographic mass spectrometric selected ion monitoring assay for the estimation of clonidine in plasma and urine using ammonia chemical ionization is described.

Proof of the linearity of the pharmacokinetics of alinidine in man

The pharmacokinetics of alinidine was investigated in two groups of volunteers: Group I (N=5) received on two occasions single doses of 14C-labelled drug given orally (40 mg) or intravenously (10 mg); Group II (N=6) received single oral doses 10, 30, or 90 mg dissolved in 20 ml water. The samples from Group I were analysed by two different and independent methods (RIA and counting total radioactivity). The results obtained by the two methods were identical, since the compound was not metabolized. The plasma concentrations and renal excretion data obtained from both groups were individually fitted to an open three compartment model. Independent of the route of administration and of the doses given, similar pharmacokinetic parameters were calculated for each group and each trial. The half lives of the distribution and elimination phases were t1/2 alpha: 36-41s, t1/2 beta: 9.9-11.1 min and t 1/2 gamma: 2.7-3.8h. There was a linear relationship between the dose administered and the resulting areas under the plasma concentration curves (AUC). Following a lag period (tau =0.19-0.22h), the peak plasma concentration was reached 0.6-1.2h after oral administration. Oral alinidine was 100% bioavailable.

Determination of submicrogram quantities of clonidine in biological fluids

A sensitive and specific GLC method using electron-capture detection was developed for clonidine in plasma and urine. Di-perfluoroacyl derivatives of both clonidine and the 4-methyl analog of clonidine (used as an internal standard) were formed, and an extraction process was developed for the removal of excess derivatization reagent and endogenous biological compounds; the assay permitted quantification of 25 pg of clonidine/ml in a 4-ml plasma sample. The assay was used to elucidate the time course of plasma concentrations in a normotensive subject following oral administration of 50, 100, and 200 microgram of clonidine hydrochloride and also to determine unchanged drug excreted in the urine.