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PubMed1999

The 20% rule: a simple, instantaneous radioactivity measurement defines cure and allows elimination of frozen sections and hormone assays during parathyroidectomy.

BACKGROUND: Although primary hyperparathyroidism is a physiologic disease, surgeons rely on anatomical characteristics (gross and histologic) to determine appropriate operative decisions. After the development of radioguided parathyroidectomy, we hypothesized that the amount of radioactivity contained within resected tissue would be the only information needed to establish the nature of the tissue and to determine a cure for the disease. METHODS: A total of 1290 tissue specimens were obtained from 345 patients who had sporadic primary hyperparathyroidism. Ex-vivo radioactivity, in counts per second, was measured in parathyroid and other tissues within 3.5 hours of sestamibi injection. Background radioactivity was measured after tissue excision, and ratios were calculated. RESULTS: Lymph nodes, normal parathyroids, and fat never contained more than 2.2% of background radioactivity, whereas thyroid and hyperplastic parathyroids contained 5.5% and 7.5%, respectively, and never more than 16%. In contrast, adenomas contained 59% +/- 9% of background radioactivity (P < .000001 vs all other tissues), with a range of 18% to 136%. CONCLUSIONS: Radioactive ratios are an instantaneous measure of metabolic activity, thereby determining parathyroid function. Any excised tissue containing more than 20% of background radioactivity in a patient with a positive sestamibi scan result is a solitary parathyroid adenoma. This alleviates the need to identify other glands, obtain frozen sections, or measure serum parathyroid hormone levels intraoperatively.

Adenoma↗

PubMed1991

Prevention of radioactive indicator and viral particle transmission with an ointment barrier.

OBJECTIVE: To determine the efficacy of a lanolin-based gel in preventing radioactive particle and viral penetration. DESIGN: Paired, stacked filter discs were held in a stainless steel support, and the gel was applied manually to the upper surface of the upper filter. Indicator solution containing either radioactive viral particles (3H-labeled simian virus 40 or 3H-labeled woodchuck hepatitis virus) or 20 microliters or 100 microliters of 32P-labeled radioactive compounds of much lower molecular weight then were applied to the upper filter. The filter discs were separated after 30 minutes, and the lower disc was examined for radioactivity in a liquid scintillation counter. RESULTS: Transmission of radioactive particles was statistically significantly reduced by the application of the ointment on the upper filter (from 6.7 +/- 0.1 x 10(5) counts per minute [cpm] to 88 +/- 38 cpm). Transmission of both labeled viral particles also was reduced to a similar degree. CONCLUSIONS: Application of protective ointment to the filters significantly reduces transmission of radioactive viral particles and smaller radioactive compounds through filter discs. Use of this ointment may offer similar mechanical protection against the transmission of viruses between patient and healthcare provider.

Equipment Contamination↗

PubMed1994

Developments in non-radioactive microsphere techniques for blood flow measurement.

Considerable progress is being made in the development of non-radioactive microsphere methods. Validation studies of the three commercially available non-radioactive microspheres are promising. In most experimental conditions the use of non-radioactive microspheres saves money. Avoiding the use of radioactivity facilitates the use of microspheres in chronic animal experiments and when blood flow and chemical measurements are performed in the same sample. Moreover, using histological techniques, distributions of coloured or fluorescent microspheres in subunits of organs could be quantified, opening new scientific possibilities. Currently, the fluorescent microsphere technique seems to be the most promising non-radioactive microsphere method. Due to the high sensitivity and good spectral separation, the number of microspheres injected can be as small as that used, for radioactive microspheres, at least six labels can be used, and the relatively large volume in which fluorescence is measured (approximately 1-3 ml) enables the use of time saving microsphere isolation techniques. Development of these methods and further automation of the quantification process (using either automised spectrometry or FACS analysis) will considerably increase interest in the non-radioactive microsphere techniques. To accelerate these developments, investigators are encouraged to share their experiences.

Animals↗

PubMed2004

Radioactivity in cathode ray tubes.

While surveying used computer equipment out of a zone posted as a Contamination Area, 100% of the computer monitors surveyed had levels of radioactivity that were significantly above background. The radioactivity was primarily on the front face of the cathode ray tube and was not amenable to decontamination. Hot spots were found also along the edges and seals of the cathode ray tube. Similar surveys of computer monitors that were never in Contamination Areas confirmed that radioactivity was incorporated into the monitor. Surveys were made of recently manufactured television sets with similar results. Gamma spectroscopy indicates that the radioactivity is due to naturally occurring radioactive materials. Since most surveys of cathode ray tubes in the literature were made while the units were energized and indicated low-energy x-rays, the use of naturally occurring radioactive materials in the manufacture of cathode ray tubes has not been widely recognized. This paper presents the results of these surveys, the results of gamma spectroscopy, and a method for releasing existing computer equipment having naturally occurring radioactive materials.

Beta Particles↗

PubMed2000

Cytogenetic studies in patients with hemophilic hemarthrosis treated by 198Au, 186Rh, and 90Y radioactive synoviorthesis.

This study assesses chromosomal structural changes (CSCs) studied by conventional lymphocyte cultures and banding techniques in 79 hemophilic patients with hemarthrosis treated with radioactive synoviorthesis, 31 hemophilic patients with hemarthrosis not treated by this procedure, and 110 nonhemophilic patients matched by age and sex (control group). In 14 patients treated with 198Au (group A), premalignant CSCs and nonspecific CSCs were found, respectively, in 1.69% and 17.23% of metaphases. The former disappeared, but 1.7% of the nonspecific changes persisted 2 years after injection. In 31 patients treated with 186Rh (group B), CSCs were not found previous to radioactive synoviorthesis but were present as nonspecific changes in 1.25% of metaphases 6 months later; they disappeared 1 year after injection. In 34 patients treated with 90Y (group C), CSCs were not found previous to radioactive synoviorthesis but were present as nonspecific changes in 0.89% of metaphases 6 months later; they disappeared 1 year after injection. Only nonspecific CSCs were found in 0.79% of metaphases in patients not treated with radioactive synoviorthesis (group D). CSCs were not present in control subjects. The authors conclude that in some hemophilic patients with hemarthosis treated with radioactive synoviorthesis using 198Au, 186Rh, or 90Y, reversible premalignant or nonspecific CSCs could be present; nonspecific CSCs may persist in a low proportion of metaphases up to 2 years after injection when 198Au is used as the radioactive agent. Radioactive synoviorthesis seems to be from a cytogenetic point of view a safe alternative for these patients.

Adolescent↗

PubMed1987

The release of radioactive arachidonate from lipids of red blood cells during prolonged incubations in vitro.

Red blood cells were isolated from rat blood and incubated in the presence of [3H]arachidonate. A sizeable quantity (18%) of the radioactivity was incorporated into red cell lipids, of which phosphatidylcholine was the most highly labelled. Radioactive arachidonate was found at position 2 of this phospholipid. Free fatty acids were removed by washing the cells in solutions containing fatty-acid-free bovine serum albumin. The labelled red cells were then incubated for up to 16 h at 37 degrees C. After 16 h of incubation in saline-buffer-glucose or rat serum, 20 and 26%, respectively, of the total radioactivity was found in free fatty acids, and there were corresponding declines in the percentage radioactivities found in phosphatidylcholine. In the presence of serum, there was a more rapid release of radioactive fatty acid over the 2- to 16-h time course. There was not a significant drop in the phosphate levels of the total red cell phospholipids or phosphatidylcholine after 16 h of incubation and, as a result, there were large declines in the specific radioactivities of phosphatidylcholine. Diacylglycerols were not highly labelled and the action of phospholipase A2 on labelled phosphatidylcholine was indicated. When white blood cells were added to labelled red cells, there was little evidence of white cell involvement in the release of radioactive fatty acid, suggesting that the red cells themselves may be involved in arachidonate release. Red cells may serve as sources of arachidonate, released following hemorrhage in brain and metabolized to form various biologically active eicosanoids.

Animals↗

PubMed1995

Low-dose radioactive endovascular stents prevent smooth muscle cell proliferation and neointimal hyperplasia in rabbits.

BACKGROUND: Restenosis induced by smooth muscle cell (SMC) migration and proliferation and neointimal thickening limits the clinical success of balloon angioplasty and stent implantation. In this study, the long-term effect of endovascular irradiation via low-dose radioactive stents on neointima formation was compared with conventional stent implantation in a rabbit model. METHODS AND RESULTS: Palmaz-Schatz stents were made radioactive in a cyclotron. The stents had a very low activity (maximum, 35 microCi), and thus, manipulation did not require extensive radiation protection. One, 4, 12, and 52 weeks after the implantation of nonradioactive stents and radioactive stents in rabbit iliac arteries, neointimal thickening was analyzed by quantitative histomorphometry. Immunostaining for endothelial cell von Willebrand factor, macrophages, SMC alpha-actin, collagen type I, and proliferating cell nuclear antigen (PCNA) was performed to determine radiation-induced changes in the arterial wall. SMC proliferation was quantified by computer-assisted cell counting of PCNA-immunoreactive cells. Neointima formation was markedly suppressed by the implantation of radioactive stents in a dose-dependent fashion at all observed time points. At peak proliferative activity of SMCs 1 week after nonradioactive stent implantation, 30 +/- 2% of SMCs in the neointima were proliferating, compared with 0.5 +/- 0.1% of SMCs after implantation of stents with an initial activity of 35 microCi (P < .001). The neointima covering radioactive stents was characterized by decreased smooth muscle cellularity and increased extracellular matrix formation. Further, we observed a delayed endothelialization depending on the radiation dose. No difference in vascular thrombosis was found after nonradioactive and radioactive stent implantation. CONCLUSIONS: The results of this study clearly indicate that low-dose radioactive endovascular stents potently inhibit SMC proliferation and neointimal hyperplasia in rabbits.

Animals↗

PubMed2004

Absorption, distribution and excretion of 14C-levofloxacin after single oral administration in albino and pigmented rats: binding characteristics of levofloxacin-related radioactivity to melanin in vivo.

After single oral administration of (14)C-levofloxacin at a dose of 20 mg kg(-1) under non-fasting conditions, the absorption, distribution and excretion of radioactivity were studied in albino and pigmented rats. Good penetration of radioactivity into tissues was indicated by higher concentrations in most tissues compared with serum and there were no quantitative differences in the distribution of radioactivity between albino and pigmented rats except for melanin-containing tissues such as the uveal tract of eyes and hair follicles. There was selective and strong binding of drug-related radioactivity to these tissues in pigmented rats. The uveal tract concentrations reached the maximum value (C(max)) of 26.33 +/- 0.75 microg eq. g(-1) at 24 h after dosing and declined slowly with a terminal half-life of 468.1 h (19.5 days). The uveal tract concentration at 12 weeks was 0.73+/- 0.12 microg eq. g(-1), which is c. 1/36 of C(max). The AUC(0- infinity ) for the uveal tract was 12.58 mg h(-1) g(-1). The uveal tracts separated from one eye of each rat were extracted with 0.067 M phosphate buffer (pH 7.4) and 1M HCl/EtOH (30:70), successively. In pigmented rats, approximately 85-48% of radioactivity bound to the uveal tract was released from the tissue by the washing procedures. Most of the eluted radioactivity was released with 1M HCl/EtOH (30:70), indicating that the binding to melanin is reversible, and hydrophobic and electrostatic interactions play an important role in the binding of levofloxacin and/or its metabolites with melanin-containing ocular tissues. Only unchanged drug was detected in the extracts of the uveal tracts. The concentrations and half-life of radioactivity in the uveal tract after dosing of (14)C-levofloxacin were found to be much lower and shorter than those after dosing of (14)C-chloroquine. It is unlikely that levofloxacin causes toxicity because of its much lower affinity to melanin-containing ocular tissues and shorter duration of therapy compared to chloroquine.

Albinism↗

PubMed2003

A new agent, blue and radioactive, for sentinel node detection.

BACKGROUND: Although with some disadvantages, combining radiotracer and isosulfan blue facilitates the detection of sentinel lymph nodes. This study was designed to evaluate the use of (99m)Tc-labeled phthalocyanine tetrasulfonate ((99m)Tc-PCTS) as a single agent for simultaneous blue staining and radiotracer localization of the sentinel lymph node. METHODS: Twelve rabbits were injected into the dermis and subcutaneously in the distal hind limb with 1 mL of blue (99m)Tc-PCTS (.5 mCi). The popliteal and inguinal fossae were explored between 15 minutes and 24 hours after injection for blue and/or radioactive tissue. Popliteal and inguinal fossae and other lymph nodes and organs were harvested for determination of the concentration of radioactivity and for histology. RESULTS: Within minutes of (99m)Tc-PCTS injection, the lymphatic channels were easily identified by the blue color. At 10 minutes, the radioactive count over the popliteal fossa was significantly higher than over other areas. At exploration, a blue and radioactive popliteal node was identified in all animals; inguinal nodes were neither blue nor radioactive. At death, the radioactivity in the popliteal node was 1000 times higher than in other nodes or organs. Although fainter, the blue color in the popliteal node was still visible at 6 weeks. Histological sections of popliteal node identified the dye in the cytoplasmic compartment of the cells. CONCLUSIONS: Technetium-99m PCTS is a single agent that identifies sentinel lymph nodes by color and radioactivity and is retained for an extended period of time without migrating to other tissues.

Animals↗

PubMed1976

Distribution of radioactivity of tritiated prostaglandins E2 and A2 in rat tissues including a renal autoradiographic study.

Distribution of radioactivity in different tissues has been studied by liquid scintillation counting 60 sec after administration of [3H] PGE2 and [3H] PGA2 in the rat. In addition, renal autoradiographs were prepared 15 sec and 60 sec after tritiated PG administration. In some experiments, [3H] PGE2 was accompanied by a large dose of PGE2 (isotopic dilution). 60 sec after [3H] PGE2 administration, radioactivity concentrates principally in the kidney, followed by the liver and the lung. Within the kidney, radioactivity concentrated predominantly in the cortex. Isotopic dilution diminished radioactivity due to [3H] PGE2 in all regions of the kidney. Renal autoradiographs 15 sec after [3H] PGE2 administration showed cortical radioactivity to be higher in glomeruli than in tubules. After [3H] PGA2 radioactivity also concentrates in the kidney, liver and lung but to a lesser extent than after [3H] PGE2 and no glomerular concentration of radioactivity was found.

Adrenal Glands↗

PubMed1978

Transmission of radioactivity into eggs from laying hens (Gallus domesticus) administered tritium labeled T-2 toxin.

The transmission of radioactivity into eggs from laying hens gastric-intubated with a single or multiple dose of 3-[3H]-T-2 toxin was investigated. In single dosed birds, the maximum radioactivity in eggs occurred at 24 hr after dosing; the yolk and white contained .04 and .13% of the administered radioactivity, respectively. In multiple-dosed birds given 8 consecutive daily doses, the radioactivity in the yolk increased with each dose, whereas the radioactivity in the white increased rapidly until the 3rd dose and thereafter remained constant. In both single- and multiple-dosed birds, the specific radioactivity of the white was greater than that of the yolk. The amount of residue transmitted into an egg in birds intubated daily with 1 mg T-2/kg for 8-consecutive days equivalent to 1.6 ppm dietary T-2) was about .9 microgram (based on specific radioactivity).

Animals↗

PubMed1975

Studies on the absorption, distribution and excretion of radioactivity after intravenous and intraperitoneal administration of 14C-methyl ester of amphotericin B.

Distribution and balance studies with carbon-14-labeled amphotericin B methyl ester (AME) were carried out in mice. The radioactive AME was administered by either the intraperitoneal (i.p.) or intravenous (i.v.) route. In the organ distribution study, the percent radioactivity accumulating in the lung of i.v. treated mice at 1 hour after administration was about 150 times greater than that observed when the intrapertinoneal route was used. No accumulation of radioactivity with time was detected in the kidneys of either the i.v. or i.p. treated mice. After 4 days, about 51% of the total radioactivity was excreted into the urine and feces of mice after i.v. administration, but only about 15% of the total radioactivity was excreted in the case of mice receiving radioactive AME by the i.p. route. In the identification of the substances excreted in the urine, thin-layer chromatography (TLC), radioactivity, and bioautographic evidence suggest that there was no detectable de-esterification of AME to the parent compound in mice treated either intraperitoneally or intravenously with AME.

Amphotericin B↗

PubMed2000

Disposition of radioactivity in fischer 344 rats after single and multiple inhalation exposure to [(14)C]Octamethylcyclotetrasiloxane ([(14)C]D(4)).

The retention, distribution, metabolism, and excretion of [(14)C]octamethylcyclotetrasiloxane (D(4)) were studied in Fischer 344 rats after single and multiple exposures to 7, 70, or 700 ppm [(14)C]D(4). Subset groups were established for body burden, distribution, and elimination. Retention of inhaled D(4) was relatively low (5-6% of inhaled D(4)). Radioactivity derived from [(14)C]D(4) inhalation was widely distributed to tissues of the rat. Maximum concentrations of radioactivity in plasma and tissues (except fat) occurred at the end of exposure and up to 3 h postexposure. Maximum concentrations of radioactivity in fat occurred as late as 24 h postexposure. Fat was a depot, elimination of radioactivity from this tissue was much slower than from plasma and other tissues. With minor exceptions, there were no consistent gender effects on the distribution of radioactivity and the concentrations of radioactivity were nearly proportional to exposure concentration over the exposure range. Excretion of radioactivity was via exhaled breath and urine, and, to a much lesser extent, feces. Urinary metabolites included dimethylsilanediol and methylsilanetriol plus five minor metabolites. Relative abundance of these metabolites was the same from every test group. Elimination was rapid during the first 24 h after exposure and was slower thereafter (measured up to 168 h postexposure). In singly-exposed female (but not male) rats, small dose-dependent shifts in elimination pathways were seen. After multiple exposures, the elimination pathways were dose- and gender-independent. These data define possible pathways for metabolism of D(4) and allow estimation of the persistence of D(4) and/or its metabolites in rats.

Administration, Inhalation↗

PubMed2000

European high-activity (32)P radioactive stent experience.

Brachytherapy by implantation of a radioactive stent is an alternative approach to catheter-based systems to reduce restenosis. The pilot clinical trials using 32P radioactive b-emitting stents at low-to-intermediate activity (0.5Eth 3.0 mCi) showed that restenosis at 6 months was not different from that of currently available non-radioactive stents. The evaluation of the efficacy in reducing restenosis of radioactive stents with higher activities (3Eth 24 mCi) started in Europe (Milan, Rotterdam and Vienna) between 1998 and 1999. In the Milan and Rotterdam experience, 32P radioactive stents with an activity of 3Eth 12 mCi demonstrated a reduction of intra-stent restenosis to < 4%. However, a high-edge restenosis > 30% was observed in the first 1Eth 3 mm outside the stent margins. This edge effect might be due to a low dose of radiation at the stent margins combined with systematic balloon injury in the reference segments. The hypothesis that a further increase in stent activity (12Eth 21 mCi) associated with a reduced balloon injury outside the stent could solve the problem of edge restenosis was not confirmed by the Milan experience; edge restenosis still occurred in 26% of the lesions treated by a single 32P radioactive stent, even if a nonaggressive stent implantation strategy was used. Two approaches under investigation to solve the problem of edge restenosis are: 1) lengthening the stent with a non-radioactive stent (cold-ends stent) to prevent negative remodeling; and 2) extending the area of irradiation beyond the balloon-injured area by an increased activity at the stent ends (hot-ends stent).

Blood Vessel Prosthesis Implantation↗

PubMed2004

Inhomogeneous localization of radioactivity in the human kidney after injection of [(111)In-DTPA]octreotide.

UNLABELLED: In peptide receptor radionuclide therapy (PRRT) using somatostatin analogs labeled with beta-emitters, the radiosensitive kidney is the dose-limiting organ, because of high uptake and retention of the radionuclides after glomerular filtration. Dosimetry calculations are mostly based on the MIRD scheme, assuming homogeneous renal radioactivity distribution. The aim of this study was to reveal the radioactivity distribution in the normal human kidney after intravenous injection of [(111)In-diethylenetriaminepentaacetic acid (DTPA)]octreotide. METHODS: Three patients received intravenous injection of [(111)In-DTPA]octreotide before nephrectomy because of renal cancer. Distribution of radioactivity in the human kidney was investigated using SPECT scanning before and ex vivo autoradiography of the kidney after surgery. RESULTS: Radioactivity was localized predominantly in the cortex of the kidney. In the cortex, radioactivity was not distributed homogeneously but formed a striped pattern, with most of the radioactivity centered in the inner cortical zone. CONCLUSION: These findings show that average dose calculations using the MIRD scheme, assuming homogeneous renal radioactivity distribution, are inadequate to estimate the radiation dose to various parts of the kidney after PRRT. Different effects due to inhomogeneity can be expected from PRRT using radionuclides emitting particles with short particle ranges, for example, Auger electron emitters, alpha-emitters, and low-energy beta-emitters.

Aged↗

PubMed2004

[Effect of 103palladium radioactive stent on expression of smooth muscle actin in bile duct during healing process and its significance].

OBJECTIVE: To observe the effect of radiation on the expression of smooth muscle actin (SMA) in the bile duct during the healing process and the inhibitory function of (103)palladium (Pd) radioactive stent on the stricture of bile duct after injury. METHODS: Twelve mongrel dogs were made models of bile duct injury: duodenotomy was performed, a balloon catheter was inserted into the general bile duct and saline with high pressure was perfused thereinto to cause laceration of the mucosa, and then the balloon catheter was withdrawn and ordinary alloy stent or (103)Pd radioactive stent was inserted into the general bile duct. Thirty days after the dogs were killed. Their bile ducts were taken out to undergo HE staining to observe the area of general bile duct, thickness of the tunica intima, area of residual bile duct cavity, stricture degree, and circumference of bile duct. The expression of SMA in the bile duct tissue was detected by immunoistochemistry. RESULTS: SMA was expressed in 5 of the 6 specimens of bile duct in the (103)Pd radioactive stent group and 2 of the 6 specimens of the ordinary stent group (P < 0.01). The maximum thickness of tunica intima of general bile duct was 0.78 mm +/- 0.12 mm in the (103)Pd radioactive stent group, significantly less than that of the ordinary stent group (1.86 mm +/- 0.14 mm, P < 0.01). The percentage of maximum stricture area of the (103)Pd radioactive stent group was 23% +/- 16%, significantly lower that that of the ordinary stent group (56% +/- 22%, P < 0.01). The circumference of bile duct cavity of the (103)Pd radioactive stent group was 9.7 mm +/- 1.6 mm, significantly longer that of the ordinary stent group (7.0 mm +/- 1.4 mm, P < 0.01). CONCLUSION: (103)Pd radioactive stent reduces the expression of SMA in the bile duct during the healing process, thus inhibiting the stricture of bile duct caused by scar contracture at the anastomotic stoma.

Actins↗

PubMed2005

Radioactive iodine therapy in Graves' hyperthyroidism: a prospective study from a tertiary referral centre in north India.

BACKGROUND: Radioactive iodine has gained widespread acceptance as the first-line therapy for Graves' hyperthyroidism and is the preferred treatment option in most situations. OBJECTIVE: A prospective study was conducted to look at the therapeutic practice of use of radioactive iodine in the treatment of Graves' hyperthyroidism, to determine whether the expected or desired therapeutic outcome is achieved. SETTINGS: A tertiary referral centre in north India, Delhi that caters to patients with thyroid disorders. METHODS: One hundred and seventy four consecutive subjects with Graves' hyperthyroidism, who were given radioactive iodine were followed up. RESULTS: There were 59 (33.9%) males and 115 (66.1%) females. The mean age was 41.8 +/- 9 years. The dose of radioactive iodine ranged from 2 mCi to 15 mCi and the mean dose administered was 5.2 +/- 1.9 mCi. After one year following radioactive iodine therapy, 29 (16.7%) subjects were euthyroid, 51 (29.3%) were hypothyroid and the remaining 94 (54%) had persisting hyperthyroidism. Those subjects with persisting hyperthyroidism at one year after radioactive iodine had received a significantly lower dose compared to the groups who had achieved cure (either euthyroidism or hypothyroidism). CONCLUSION: The study shows that the current practice of empirical low dose radioactive iodine therapy to avoid hypothyroidism results in majority of patients having persisting hyperthyroidism. There is a need to take a new look at the current practice to increase the cure rate.

Adult↗

PubMed1984

Absorption, distribution and excretion of radioactivity after a single intravenous or oral administration of [14C] glucosamine to the rat.

Blood levels, tissue distribution and excretion patterns of radioactivity were studied in the rat after administration of [14C] glucosamine sulphate by the intravenous or oral route. After intravenous administration, plasma radioactivity declined in the first 30 min, then increased, reaching a peak at the 2nd hour, and disappeared, with a half-disappearance time of 28 hours. The radioactivity diffused rapidly in the tissues. Higher levels than in plasma were reached in the liver and kidneys. There was early incorporation of radioactivity in the skeletal tissues (cartilage and bone). About 50% of the administered radioactivity was excreted with the expired CO2 and about 35% with the urine. Faecal excretion was small (2% of the administered dose). After oral administration, radioactivity was quickly found in plasma, where it reached a peak at 4 hours. It then declined slowly, with biphasic kinetics. The tissue distribution, including uptake in the skeleton, repeated the pattern found after intravenous administration. There was only small faecal excretion, showing an almost complete bioavailability of glucosamine given orally, and the large excretion with the CO2 (82%) showed that glucosamine is to a large extent broken down to smaller fragments. Autoradiographic studies confirmed the tissue distribution pattern and showed in more detail the tissue localization of radioactivity.

Administration, Oral↗