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At least 19 recordsLinked to original sources
PubMed1978

Low dose lithium-carbimazole in the treatment of thyrotoxicosis.

Fifteen patients with thyrotoxicosis were treated with low dose sustained release lithium carbonate 400 mg, combined with carbimazole 40 mg daily, and the therapeutic response was followed over a two week period. This response was compared with that obtained in a similar group of patient treated with carbimazole alone. Li-carbimazole treatment brought about a fall in the mean total serum T4 of 57.4% compared with a drop of 32.8% in patients treated with carbimazole alone. The mean serum T3 fell by 69.4% in the Li-carbimazole group compared with 47.3% in the group treated with carbimazole only. No lithium adverse effects were encountered.

Antithyroid Agents↗
PubMed1977

The placental transfer of propylthiouracil, methimazole and carbimazole.

The placental transfer of 35S-labelled methimazole (MMI), carbimazole and propylthiouracil (PTU) has been examined in the rat in late pregnancy and in patients undergoing therapeutic abortion. Although rapid equilibrium of fetal and maternal serum radioactivity (FS:MS ratio 1:1) occurred after iv administration of 35S-carbimazole or 35S-MMI in rats, a persistent fetal to maternal ratio of less than one was observed after 35S-PTU administration. Results from human studies after a single oral dose indicate that, as in the rat, the placenta appeared to be more permeable to 35S-MMI than to 35S-PTU as shown by the marked difference in fetal serum:maternal serum ratios and amounts accumulated in the fetus. Localization of radioactivity in the human fetal thyroid was also observed after administration of 35S-labelled MMI, carbimazole or PTU.

Abortion, Induced↗
PubMed1976

An evaluation of lithium as an adjunct to carbimazole treatment in acute thyrotoxicosis.

The rate of control of thyrotoxicosis during the first 2 weeks of treatment was documented in 63 patients. Twenty-three patients received carbimazole 40 mg plus lithium carbonate 750 mg daily and a comparable group of 20 patients were given carbimazole 40 mg plus potassium iodide 120 mg daily. In the lithium treated patients the mean percentage fall of serum T4 after 2 weeks treatment was 49% and the fall in serum T3 57%. The results were similar in the iodide treated patients; the mean falls in serum T4 and T3 being 47% and 64%, respectively. Serum lithium values varied between 0.1-1.25 mEq./l; lithium side effects were minor. In a companion study 20 patients were treated with carbimazole alone. The responses in this group were less impressive; the mean falls in serum T4 and T3 at 2 weeks being 18% and 36%, respectively. It is concluded that lithium is a safe adjunct to conventional antithyroid drug therapy in the initial treatment of acute thyrotoxicosis.

Acute Disease↗
PubMed1979

Rapid conversion of carbimazole to methimazole in serum; evidence for an enzymatic mechanism.

Carbimazole (CBZ) is one of the major drugs currently used for the treatment of Graves' disease. It is a carbethoxy derivative of methimazole (MMI), originally developed in the hope of obtaining a longer acting drug than methimazole. In the present study we have demonstrated that carbimazole is rapidly converted to methimazole in vitro by serum from rats and humans, and we have obtained evidence that this conversion is enzymatic. Experiments with [35S] CBZ in rats showed that the drug is so rapidly transformed to MMI after i.v. injection (within 3 min) that very little of the unchanged drug would be expected to reach the thyroid gland. The antithyroid action of CBZ in rats, therefore, can be ascribed entirely to the MMI to which it is rapidly converted. Although no experiments were performed with human subjects in vivo, the very rapid conversion of CBZ to MMI by human serum in vitro suggests that the antithyroid action of CBZ in humans can also be attributed to MMI. The original expectation of a longer acting drug has, therefore, not been met by CBZ. On the basis of the studies reported here there appears to be no advantage in using CBZ in preference to MMI for the treatment of Graves' disease. Although the in vivo action of CBZ must be attributed to its rapid conversion to MMI, the drug does possess inherent antithyroid activity. This was shown in the present study by the finding that CBZ is as potent as MMI in blocking thyroid peroxidase-catalysed iodination of thyroglobulin.

Animals↗
PubMed1975

Jaundice due to carbimazole.

On three occasions, a 63 year old housewife with hyperthyroidism developed a reaction which included fever, pruritus, malaise, and, on one occasion, jaundice one to 17 days after taking carbimazole. Challenge with carbimazole was followed within 12 hours by abdominal pain, pruritus, and increased serum transaminase levels. Light microscopy of a liver biopsy showed increase of portal zone cellularity over the control and the electron microscopy revealed fine structural changes compatible with drug-related liver injury.

Aspartate Aminotransferases↗
PubMed1978

Extrathyroidal effects of propylthiouracil and carbimazole on serum T4, T3, reverse T3 and TRH-induced TSH-release in man.

A possible extrathyroidal effect of propylthiouracil (PTU) and carbimazole on serum levels of thyroxine (T4), triiodothyronine (T3), 3,3',5'-triiodothyronine (reverse T3) and on thyrotrophin-releasing hormone (TRH) induced thyrotrophin (TSH) release was estimated in 19 patients with severe hypothyroidism treated with T4. During PTU medication a significant decrease in serum T3 from 90 +/- 16 (SD) to 79 +/- 23 ng/100 ml (P less than 0.01) and a reciprocal increase in serum reverse T3 from 51 +/- 14 (SD) to 58 +/- 20 ng/100 ml (P less than 0.025) were found. No significant changes in serum T4, basal serum TSH or response to TRH could be demonstrated. Carbimazole did not change any of the parameters studied.

Adult↗
PubMed1979

Mode of action of carbimazole in Graves' disease.

In a series of hyperthyroid subjects treated with a high dose 'block-replace' regime, mean thyroidal technetium uptake was shown to fall progressively over an 18 month period. Furthermore, sub-total inhibition of hormone biosynthesis could be demonstrated, without evidence of proportionate inhibition of organification, the regression of radio-iodine on technetium thyroid uptake showing similar slopes in euthyroid, treated and untreated hyperthyroid subjects. Together with the reported differential in remission rates between propranolol and anti-thyroid drugs, it is concluded that carbimazole does not act solely by inhibiting intrathyroid hormono-genesis, but more definitively by affecting thyroid hyperstimulation at a pre-biosynthetic level. The inability to demonstrate normal suppressibility of trapping in any subject in the present series despite extended therapy with a 'block-replace' regime, further suggests that current concepts of 'suppressibility' are invalid, the progressive fall in technetium uptake being unlikely to represent spontaneous restoration of a normal pituitary-thyroid axis, but rather a direct influence or prolonged therapy with anti-thyroid drugs on the natural history of the disease.

Adolescent↗
PubMedDate not supplied

Bioavailability of two tablet preparations of carbimazole in man.

1. The bioavailability of two 5 mg tablet formulations of carbimazole (Neomercazole [A] and Carbazole [B]) have been compared in six euthyroid subjects. There was considerable inter-patient variation in absolute bioavailability although, for each subject, peak plasma concentrations of methimazole were similar with both formulations. 2. Mean peak plasma concentrations were seen on average 62 min after administration of tablet A as compared to 40 min after tablet B. This is consistent with the finding that the disintegration and dissolution times were shorter for formulation B than for formulation A. The mean area under the plasma concentration curve and the 6 h plasma concentration of methimazole tended to be greater after tablet A. These differences could be of significance in the treatment of thyrotoxicosis.

Adult↗
PubMed1976

Long-term assessment of children exposed in utero to carbimazole.

Twenty-five children aged 3 to 13 years who had been exposed in utero to carbimazole were assessed physically and psychologically to evaluate the long-term effects of the drug on growth and development. 2 children had congenital malformations but all had normal pituitary-thyroid function and appeared to have grown and developed normally.

Abnormalities, Drug-Induced↗
PubMed1977

Thyrotoxicosis: relations between clinical state and biochemical changes during carbimazole treatment.

The relation between clinical and biochemical changes in thyrotoxicosis were studied in 12 patients with Graves's disease who were being treated with carbimazole. Clinical assessment (using the Crooks-Wayne index) was combined with the measurement of free thyroxine and triiodothyronine indices (FT4I and FT3I) and the assessment of two tissue markers of thyroid hormone action--sex-hormone-binding globulin (SHBG) levels and the thyrotrophin responses to TRH. In general the FT4I and FT3I fell rapidly once treatment was started, and returned to normal in one to four weeks, followed shortly by SHBG levels. The thyrotrophin response returned at this time in two patients, who still had borderline high levels of FT3I and SHBG. The clinical score fell more slowly and variably and was less closely related to any of the biochemical indices than these were to each other. During the early phase of treatment with antithyroid drug the clinical evaluation may be an unreliable indicator of persisting thyroid hormone excess, and when the patient seems clinically but not biochemically thyrotoxic the symptoms should be treated on their own merits with beta-blocking drugs and not with increased doses of antithyroid drugs.

Adult↗
PubMed1977

Identification of 3-methyl-2-thiohydantoin, a metabolite of carbimazole, in man.

1. Classical and high-pressure liquid chromatographic separations were devised for the separation and isolation of the metabolite 3-methyl-2-thiohydantoin from the urine of patients receiving carbimazole orally. 2. 3-methyl-2-thiohydantoin was identified by comparing its absorption and mass spectral properties with authentic material. 3. 3-methyl-2-thiohydantoin was also detected in the plasma of patients receiving methimazole intravenously.

Carbimazole↗
PubMedDate not supplied

[Serum thyroid hormones and TSH response to TRH during treatment of Graves' disease by carbimazole (author's transl)].

Serum concentrations of Thyroxine (T4), triiodothyronine (T3) free thyroxine index (F.T.I.) and TSH response to TRH were evaluated in 55 Graves' diseases treated by Carbimazole. There is a good correlation between serum thyroid hormones and clinical state: 83,7% for T4; 79,5% for T3; on the other hand there is a discrepancy between T3 and T4 in many cases and between delta TSH and T4 (47%) or T3 (46%). The decrease of T4 occurs before that of T3: 46,6% normal at the 4th month and 72,5% at the 9th month for T4 against 41% and 50% for T3. At the end of the treatment 96,4% of patients are clinically normal but 20% of them remain with T3 and T4 values above normal.

Carbimazole↗
PubMed1978

[Serum thyroid hormones in hyperthyroid patients treated with carbimazole (author's transl)].

Serum thyroxine (T4), triiodothyronine (T3) and thyrotropin (T.S.H.) were measured in 32 hyperthyroid patients treated with carbimazole. A discrepancy between serum T4 AND T3 was present in 73 of 131 measurements: --normal T3 with increased T4 in 6 measurements; --increased T3 with normal T4 in 16 measurements: five times only there was a clinical hyperthyroidism; --normal T3 with decreased T4 in 49 measurements: three times only there was a clinical hypothyroidism. Serum T.S.H. level was increased in 13 of 19 measurements made in this group, state named "compensated hypothyroidism" according to Patel and Burger.

Carbimazole↗
PubMed1978

Mitotic rate of the rat's thyroid gland during hypertrophy induced by an antithyroid agent (carbimazole).

Female rats (200 g body weight) were either untreated or given carbimazole (0.1 g/100 ml) in their drinking water for up to 12 weeks. The mitotic rate of the thyroid follicular cells was estimated using vincristine sulphate. Measurement of whole-body oxygen consumption showed that the rats were clearly hypothyroid after 1 week of treatment. The mitotic rate rose rapidly from the control value of 3.65% metaphases/day to about 25%/day after 4 days and was maintained at this level for at least 5 weeks of treatment. The changes in mitotic rate were apparently synchronous with the histological changes. The results of earlier studies are reviewed and discussed in relation to recent concepts of cell populations.

Animals↗