Iodine-123-iodo-lisuride SPECT in Parkinson's disease.

UNLABELLED: Recently, [123I]iodo-lisuride was synthesized for possible applications in SPECT studies. The purpose of this investigation was to compare the striatal binding and kinetics of this radioligand in patients with Parkinson's disease and normal controls. METHODS: Six patients with Parkinson's disease and three normal controls were examined. After intravenous injection of 111 MBq [123I]iodo-lisuride, sequential SPECT examinations at 20, 40, 80 and 120 min were performed. For each SPECT series the basal ganglia-to-cerebellum ratio of tracer accumulation was calculated. In one patient a repeat SPECT examination was undertaken under identical conditions to test the reproducibility of the procedure. In two other patients a second SPECT examination was performed after injection of cold lisuride as a receptor saturation study. In addition, the time course of the radioactivity was measured in the plasma and red blood cells in each individual. RESULTS: In both patients and controls, the highest tracer accumulation was found within the striatum. The basal ganglia-to-cerebellum ratio was 1.182 and 1.303 at 20 min, 1.353 and 1.450 at 40 min, 1.490 and 1.533 at 80 min, 1.550 and 1.583 at 120 min for patients and controls, respectively, which was not statistically different. In the saturation study, 50 micrograms and 100 micrograms cold lisuride led to a 28% and 33% reduction, respectively, of the basal ganglia-to-cerebellum ratio at 120 min. The ligand showed a rapid decline in plasma and red blood cells. The percent injected dose per liter was calculated to be 1.6 and 0.9, respectively, for plasma and red blood cells at 20 min. CONCLUSION: Iodine-123-iodo-lisuride SPECT seems useful for imaging intact striatal dopamine D2 receptors in patients with Parkinson's disease and may provide clinically relevant information for quantitative assessment of the availability and integrity of dopamine D2 receptors.

[Brain SPECT with 123I-lisuride in patients with Parkinson's disease and controls]. / Hirn-SPECT mit 123I-Lisurid bei Morbus-Parkinson-Patienten und Kontrollen.

The goal was to visualize cerebral dopamine-D2 receptors in 6 patients with Parkinson's disease and in 3 healthy controls using iodine-123-Lisuride-SPECT. In addition, we performed receptor-replacement studies using 123I-Lisuride and cold Lisuride as competitive ligands. The highest uptake of 123I-Lisuride was observed in the striatum, a region with known high dopamine receptor density. In two patients premedication with cold Lisuride displaced 123I-Lisuride from the dopamine receptor. 123I-Lisuride is valuable as a radiotracer in cerebral dopamine-D2 receptor scintigraphy. Whether or not it is possible to determine dynamic changes of dopamine receptor density or function by receptor replacement studies needs further evaluation in larger patient populations.

Progestin receptor cells in mouse cerebral cortex during early postnatal development: a comparison with preoptic area and central hypothalamus using autoradiography with [125I]progestin.

The distribution of progestin target cells in the cerebral cortex and the effect of estrogen treatment was assessed during the critical period of brain development and compared with the preoptic/central hypothalamic regions. [125I]progestin was injected into 0, 2, 8, and 12 day postnatal mice pretreated for 3 days with oil, 5 micrograms/100 g b, wt., or 100 micrograms/100 g b. wt. of estradiol dissolved in oil. Two hours after injection of radiolabeled ligand, brains were frozen and processed for thaw-mount autoradiography. At birth, labeled cells were detected in the deep (lamina VI) and intermediate (lamina V) layers of the lateral cortical regions, increased in laminae V-VI of the lateral cortex and laminae II-VI of the cingulate/paracingulate cortex at days 2 and 8, and decreased throughout the cortex by day 12. Pretreatment of animals with estradiol had no noticeable effect on the nuclear concentration of [125I]progestin in cortical cells, while estrogen weakly enhanced labeling in preoptic/central hypothalamic regions at day 2 and markedly augmented labeling in the 8 and 12 day brain. The results demonstrated that progestin receptor cells are present in the postnatal dorsal cortex, preoptic area, and hypothalamus and that the topography of cortical progestin target cells differs in part from that of estrogen target cells reported earlier.

Progestin receptor cells in the 8-day-old male and female mouse cerebral cortex: autoradiographic evidence for a sexual dimorphism in target cell number.

The present study examined the number and distribution of progestin receptor cells in the 8-day-old male and female cortex and compared cortical labeling with that in the preoptic area and central hypothalamus. Eight-day postnatal mice (four males and four females), treated with estradiol, were each sc injected with 0.32 micrograms/100 g BW [125I]progestin (SA, 2200 Ci/mM). Brains were frozen 2 h after injection of [125I]progestin, sectioned, and processed for thaw-mount autoradiography. Cells with a nuclear concentration of radioactivity were localized in lamina VI of the lateral cortical regions of the male and female brain, while only a few cortical cells were seen in laminae II, III, and V of the suprarhinal, lateral, and cingulate/paracingulate regions. Comparison of the number of labeled cells revealed that the female cortex contained significantly more labeled cells than the male at three of the four levels investigated. Similarly, the number of target cells was higher in the female medial preoptic nucleus, but not in the arcuate nucleus and ventromedial hypothalamic nucleus, while the distributions of labeled cells in the male and female preoptic/hypothalamic regions were comparable. Injection of unlabeled progesterone or R5020 1 h before [125I]progestin reduced the nuclear concentration of radioactivity in all target regions and verified the specificity of [125I]progestin for the progestin receptor. The results of these studies indicate that mouse 8-day-old cortex and preoptic area in the female animal have more progestin receptor cells than those in the male and demonstrate that progestin receptor cells are localized in a region of the cortex known to contain few estrogen target cells. These results further suggest that a sexual dimorphism in progestin cell number may result in a differential effect of progestin on the cortex and preoptic area of the mouse, perhaps establishing a dimorphism in development and function.

Distribution of progestin-binding cells in estrogen-treated and untreated neonatal mouse uterus and oviduct: autoradiographic study with [125I]progestin.

Progestin-binding sites in uteri and oviducts of estrogen-treated and untreated 8-day-old mice were studied by thaw-mount autoradiography with [125I]progestin. In the untreated uteri, nuclear concentration of radiolabelled progestin was observed in all tissues of the uterus, with strongest nuclear labelling in luminal and glandular epithelia and in stroma. In the estrogen-treated uteri, the degree of labelling was markedly augmented in stroma and muscle, but much reduced in the luminal and glandular epithelia, compared to untreated uteri. In untreated oviducts, nuclear labelling was observed in stroma and muscle in all regions and in epithelium in the isthmic and uterine regions. The epithelium in infundibular and ampullar regions was only scarcely labelled. The estrogen-treatment augmented the labelling in stroma and muscle of the oviduct as in the uterus, but the labelling in epithelium was not affected. These results indicate that estrogen-treatment induces progesterone receptor differentially among tissue compartments both in the uterus and oviduct.

Whole body autoradiographic distribution studies on nonionic x-ray contrast agents in pregnant rats.

The time course of the distribution of radioactive label in organs and tissues was investigated after intravenous administration of iotrolan, iopamidol, iopromide, and iohexol in a concentration of 60 mg I/ml (2.2 MBq 125I/mg I) as aqueous solution to pregnant rats (18th day after conception) by a whole-body autoradiographic technique. All contrast agents were rapidly distributed within the organism, showing equal distribution patterns of radioactivity, and were rapidly excreted, mainly by the kidney. Passage of radioactivity across the blood-brain and placental barriers could not clearly be shown. No specific and long-lasting retention of radioactivity could be seen in any organ or tissue with the exception of the thyroid.

Progestin receptors in brain and pituitary of 20-day-old fetal mice: an autoradiographic study using [125I]progestin.

The distribution of progestin target sites in the brain and pituitary of estrogen-primed 20-day-old fetal mice was investigated by thaw-mount autoradiography. Three pregnant mice were each implanted sc with a Silastic tube containing estrogen on day 17 and ovariectomized on day 19 of gestation. Twenty-four hours after ovariectomy 10 fetuses (5 males and 5 females) were collected and each injected sc with 0.33 microgram/100 g BW [125I]progestin (SA, 2200 Ci/mM). For competition, two additional fetuses were injected with 20 micrograms R5020 1 h before (Z)-17 beta-hydroxy-17 alpha-(2[125I]iodovinyl)4-estren-3-one [( 125I]Progestin) to demonstrate that nuclear uptake and retention of radioactivity were specific for progestin. Two hours after injection of [125I]Progestin all fetuses were mounted, frozen, and sectioned in a cryostat. After 1-37 days of exposure, sections were developed and scanned for labeled cells. Cells with nuclear concentration were found in the male and female preoptic area, within certain nuclear groups in the basal hypothalamus, in the central gray of the midbrain, and in the pituitary. No labeling was detected in the cortex or amygdala. The results indicate that cells in certain regions of the brain and pituitary express progestin receptors at the end of gestation and suggest that progesterone is important for the normal development of these cells.

(Z)-17 beta-hydroxy-17 alpha-(2-[125I]iodovinyl)-4-estren-3-one: a new specific gamma-emitting ligand for determination of progesterone receptor.

An iodine-125 labeled ligand for progesterone receptor determination was synthesized: (Z)-17 beta-hydroxy-17 alpha-(2-[125I]iodovinyl)-4-estren-3-one ([125I]SH-D 510). The ligand is stable chemically as well as under the conditions of a receptor assay. The relative binding affinity of the nonradioactive compound towards human uterine progesterone receptor was 7.0 for the Z-isomer (promegestone (R5020) 1.0) and 0.95 for the E-isomer. 4 S and 8 S receptor forms were obtained on sucrose density gradient analysis. Progesterone receptors were assayed in 103 human mammary tumour cytosols, using either [3H]promegestone or [125I]SH-D 510. The coefficient of correlation was r = 0.951.

Whole-body autoradiographic studies in rats with gadolinium-diethylenetriaminepentaacetic acid, a new contrast agent for magnetic resonance imaging.

The time course of the distribution of radiolabel in organs and tissues was investigated after intravenous administration of 0.5 mmol/kg of 14C-labelled gadolinium-diethylenetriaminepentaacetic acid (Gd-14C-DTPA) and of 153Gd-DTPA to pregnant rats (18th day p.c.) and after intragastric administration of 30 mumol/kg of Gd-14C-DTPA to male rats by whole-body autoradiographic technique. After intravenous administration Gd-DTPA was rapidly distributed within the organism. The distribution pattern was similar to that of classical X-ray contrast agents like diatrizoate and iotalamic acid. Gd-DTPA was not able to pass blood-brain and placental barriers. There was no indication of a dissociation of Gd-DTPA complex. 24 h after i.v. injection most of the radiolabel left the body. Only very small amounts were found in the kidney, the placenta and in the contents of the intestine. No specific and long-lasting retention of radioactivity was observed in any organ and tissue. After intragastric administration Gd-DTPA was not absorbed.

Development of antibody-mediated extraction followed by GC/MS (antibody/GC/MS) and its application to iloprost determination in plasma.

A new analytical principle has been developed combining the features of both radioimmunoassay and GC/MS. Its application in eicosanoid analysis was tested with the prostacyclin analogue, iloprost. The iloprost antibody, generally employed in RIA measurements, was coupled to Sepharose 4B and used as stationary phase for extraction of the drug. Variations in recovery were corrected by using deuterated iloprost as an internal standard. The samples were derivatized and quantitated by negative-ion chemical ionization-mass spectrometry. Reproducibility was 2.3 % at the 50 pg/ml level and the limit of detection was 5 pg for 1 ml samples. With plasma volumes of up to 20 ml, 0.25 pg/ml could be determined. Antibody/GC/MS proved superior to radioimmunoassay due to its higher specificity and sensitivity and superior to GC/MS with conventional clean-up procedures because of a higher sample capacity.

Pharmacokinetics of the stable prostacyclin analogue, nileprost, in the rat.

The synthesis of radioactive nileprost, tritium-labelled at positions 18 and 19, and its application to the pharmacokinetics and biotransformation of this chemically stable prostacyclin derivative in the rat is described. 3H-Nileprost was absorbed after oral administration with a half-life of 23 min reaching maximum concentrations in the plasma 90 min after treatment. After intravenous injection there was a threephasic decline in plasma levels with half-lives of 15 min, 0.9 h and 11 h, respectively. Unchanged drug was eliminated with t 1/2 = 14 min. Brain levels of drug or metabolites were less than 5% of corresponding plasma concentrations. In autoradiographs after i.v. and oral administration a very low volume of distribution was found with maximum levels in the liver, the kidney and the stomach mucosa. Nileprost was very rapidly excreted, mainly by biliary elimination. Ten metabolites were detected in urine and bile, one of them being formed exclusively in the gut wall. The main fraction of 3H-activity in urine and bile, however, was due to unchanged drug.

Development and preliminary pharmacologic evaluation of a zwitterionic oral cholecystographic agent.

A new zwitterionic iodinated molecule, 2-[3-(N-ethyl-2-hydroxyethyl) amino-acetamido-2, 4, 6-triiodobenzyl]-butyric acid (RCK-136) was synthesized, and its potential as an oral cholecystopaque was tested. In rats, 15 minutes following intravenous injection, RCK-136 reached maximum biliary concentration; 84% of the dose was excreted into bile. Biliary excretion of RCK-136 elicited a strong choleresis (44 ml of bile flow per mmol compound). Intravenous LD50 in rats averaged 390 mgI/kg. ED50 in rats, intradiencephalic, averaged 1.98 mgI/kg. The average densities of cholecystograms produced in three dogs with iosumetic acid and/or RCK-136 were comparable.

Quantitative analysis of norethindrone in milk using deuterated carrier and gas chromatography-mass spectrometry.

PIP: A quantitative procedure using deuterated carrier and gas chromatography-mass spectrometry is described and applied to quantitate norethindrone levels in milk from 5 lactating women, aged 20-30 years, who had received 1 silastic implant of 40 mg of norethindrone. The technique is a multiple ion one (gas chromatography-mass spectrometry). The deuterated norethindrone was used as the internal standard and carrier for the detection technique, and, after its addition, the milk samples were extracted with Amberlite XAD-2 columns and purified on Sephadex columns. O-methoxime-trimethylsilyl ether derivatives of the purified samples were analyzed. The assay was precise and reproducible. The mean level of norethindrone at 3 weeks post implant insertion was 208 pg/ml of milk, after which it declined slowly and steadily.^ieng

A new principle of injectable depot contraceptives. I Drug selection and studies in monkeys.

The aim of the investigations was to develop a long-acting depot contraceptive on the basis of norethisterone or levonorgestrel. Disappointing results with levonorgestrel nonanoate and levonorgestrel undecylate showed that elongation of the fatty acid, esterified with the steroid, decreased the bioavailability of the latter due to incomplete hydrolysis of the ester. Therefore, several new compounds were synthesized which contained a bifunctional molecule between the steroid and the fatty acid. In vivo studies showed an increase in hydrolysis when glycolic acid was taken as the "bridge", compared to the hitherto known esters. Due to the new principle of the steroid-fatty acid connection, in the case of norethisterone, it was possible to introduce tridecanoic acid as lipophilic release controlling substituent without a loss of bioavailability in the baboon. This compound (called: "norethisterone glycotridecanoate") and the corresponding levonorgestral derivative were chosen for a pharmacokinetic-clinical study in women.

Bioavailability and pharmacokinetics of cyproterone acetate after oral administration of 2.0 mg cyproterone acetate in combination with 50 micrograms ethinyloestradiol to 6 young women.

PIP: The bioavailability and pharmokinetics of cyproterone acetate (CA) were studied in 6 healthy young women. The subjects received a single oral dose of 2 mg carbon-14-CA plus 50 mcg tritiated-ethinyl estradiol. Matimum plasma levels of CA were observed about 4 hours after administration. During the 4-10 hours following administration, carbon-14-CA in plasma disappeared with a half-life of 3 + or -1.6 hours. The half-life for the subsequent phase of disposition was 1.7 + or -.5 days. The apparent volume of distribution for CA was 1300 + or -580 liters. Although plasma equivalents of carbon-14-CA had higher absolute values, the course of their distribution was similar to those concentrations for the unchanged drug. 88 + or -11% of the dose was recovered and 30.4 + or -7.3 excreted in urine. The concentration of the primary metabolite of CA in plasma showed a decline which paralleled the terminal disposition phase of CA; the elmination half-life being 1.8 + or -.1 days. The apparent distribution volume for the primary metabolite was 95 + or -25 liters. CA, in comparison with its primary metabolite, had 10 times the apparent distribution volume. Approximately 90% of CA was present at all times following administration. In terms of total activity, the proportion of CA in plasma remained constant 1/2 day after administration. It is suggested that the transfer of CA from tissues determines the rate of metabolization of CA and the excretion of metabolites.^ieng

Injectable depot contraceptives on d-norgestrel basis. I. Pharmacokinetic studies in dog and baboons.

PIP: The pharmacokinetics of 5 d-norgestrel 17beta-fatty acids with 6-16 carbon atoms, administered im, were studied in dogs and baboons. d-Norgestrel 17beta-undecylate and d-norgestrel 17beta-nonanoate most closely approached the optimum for uniform release over a 3-month period. In baboons, it was found that the bioavailability of d-norgestrel depended on the chain length of the esterified fatty acids, irrespective of the assay methods. Approximately 50% of d-norgestrel 17beta-nonanoate and 25% of d-norgestrel 17beta-undecylate is converted into de-norgestrel and fatty acid residue after release. After 3 months of treatment, both substances produced plasma levels of d-norgestrel which were equivalent to a daily d-norgestrel release of about 30 mcg. Since fluctuations in drug levels were less pronounced with d-norgestrel-C(11), it appears that this substance is suitable for study in humans.^ieng

Bio-availability and pharmacokinetics of cyproterone acetate-14C and ethinyloestradiol-3H after oral administration as a coated tablet (SH B 209 AB).

PIP: Bioavailability and pharmacokinetics of carbon-14-cyproterone acetate-methylene (2 mg) and tritiated ethinyl estradiol (50 mg) after oral administration as a coated tablet (SH B 209 AB) were investigated. 8 women received the compounds, and carbon-14 and tritium activity in plasma, urine, and feces was determined up to 7 or 10 days postadministration. Cyproterone acetate was completely absorbed. The maximum plasma level was reached in 30 minutes to 3 hours, when 2.2% of the dose was found in total plasma corresponding to 24 ng eq/ml. The plasma level decreased with a 1/2-life of 7.9 hours (distribution and elimination) and later with a 1/2-life of 2.5 days (elimination). Elimination via urine was 37% and up to Day 10 postadministration 91% of the dose was found in urine and feces. Ethinyl estradiol was adsorbed very rapidly and almost completely with the maximum plasma level reached in 60 minutes. At this time 10% of the dose was found in the plasma corresponding to 2.1 ng eq/ml. The plasma level dropped up to about 8 hours postadministration with a 1/2-life of 5.1 hours and later with a 1/2-life of 27 hours. Ethinyl estradiol was eliminated in urine and feces in the ratio of 4:6 and 91% of the dose was recovered.^ieng

[Bioavailability and pharmacokinetics of 14C-cyproterone acetate after administration as a 50-mg tablet (author's transl)]. / Bioverfügbarkeit und Pharmakokinetik von 14C-Cyproteronacetat nach Applikation als 50-mg-Tablette

Four male volunteers were each given a 50 mg oral dose of methylene-14C-labelled cyproterone acetate in a formulation largely identical to the commercial preparation Androcur Tablets. A further 3 volunteers were each given 10 mg of the 14C-labelled compound by intramuscular injection. Plasma samples were obtained and urine and faeces collected quantitatively from each volunteer up to 10 days post administration. 1. Absorption of the 50 mg of cyproterone acetate administered in the form of Androcur Tablets was largely complete. 2. The maximal plasma level of 400 +/- 40 ng cyproterone acetate equivalents/ml of plasma, calculated from the 14C activity, was found 3,8 +/- 0,5 hours after oral administration. By 10 hours post administration the plasma level had declined with a half-life of 7,9 +/- 2,5 hours (distribution and elimination). The fictitious distribution volume assignable to this process amounted to 140 +/- 40% of body weight. Plasma 14C-activity then decreased with a half-life of 1,8 +/- 0,2 days, which was consistent with elimination. 3. The labelled substance was almost completely extractable from plasma and could be separated by chromatography into 2 fractions of about equal size: cyproterone acetate and one metabolite. 4. Orally administered cyproterone acetate was eliminated with a half-life of 1,6 +/- 0,1 days. By 10 days post administration 33 +/- 6% of the dose had been detected in urine and 60 +/- 8% in faeces. Up to this time total elimination amounted to 93 +/- 5% of the dose. 5. After intramuscular injection of 10 mg of cyproterone acetate the half-life for absorption from the muscular depot was 7,0 +/- 0,2 hours. Between 2 and 10 days post administration there was a uniform decrease in plasma level and urinary elimination with half-life of 2,3 +/- 0,1 days and 2,1 +/- 0,2 days respectively. By the end of the trial 34 +/- 5% of the dose had been eliminated with urine and 57 +/- 6% with faeces.