Antithyroid drugs

Over the past four decades, a great deal has been learned about the pharmacology and mechanisms of action of antithyroid drugs. Their ability to inhibit hormone biosynthesis involves complex interactions with thyroid peroxidase and thyroglobulin, many of which are still poorly understood. Their spectrum of activity is much wider than previously thought, and a number of clinically important extrathyroidal actions have been identified. Despite a greater appreciation for the intricacies of antithyroid-drug pharmacology, controversies still surround the use of these agents in the treatment of thyrotoxicosis. These controversies are apt to continue until the pathophysiology of Graves' disease is fully elucidated.

Occurrence of ophthalmopathy after treatment for Graves' hyperthyroidism. The Thyroid Study Group

BACKGROUND

Ophthalmopathy caused by Graves' disease may first appear or worsen during or after treatment for hyperthyroidism. It is not known, however, whether choosing to treat hyperthyroidism with antithyroid drugs, iodine-131, or surgery affects the development or aggravation of Graves' ophthalmopathy.

METHODS

We studied 168 patients with hyperthyroidism caused by Graves' disease, stratified into two age groups--20 to 34 years (54 patients, group 1) and 35 to 55 years (114 patients, group 2). The patients in group 1 were randomly assigned to treatment with methimazole for 18 months or subtotal thyroidectomy, and those in group 2 to either of these two treatments or to iodine-131 therapy. All the patients received thyroxine to avert hypothyroidism, except those treated with iodine-131, who received thyroxine only if hypothyroidism developed. The duration of follow-up was at least 24 months.

RESULTS

Twenty-two patients (13 percent) had infiltrative Graves' ophthalmopathy at randomization. During follow-up, ophthalmopathy developed for the first time in 22 patients (13 percent) and worsened in 8 patients (5 percent). The frequency of the development or worsening of ophthalmopathy was similar among the patients in group 1 (medical therapy, 4 of 27 patients [15 percent]; and surgery, 3 of 27 patients [11 percent]). In group 2, ophthalmopathy developed or worsened in 4 of the 38 patients (10 percent) treated medically, 6 of the 37 patients (16 percent) treated surgically, and 13 of the 39 patients (33 percent) given iodine-131 (P = 0.02 for the comparison between the iodine-131 subgroup and the others combined). The risk of the development or worsening of ophthalmopathy increased as pretreatment serum triiodothyronine concentrations increased.

CONCLUSIONS

As compared with other forms of antithyroid therapy, iodine-131 is more likely to be followed by the development or exacerbation of Graves' ophthalmopathy.

Maternal hyperthyroidism and congenital malformation in the offspring

Six hundred and forty-three neonates from mothers with Graves' disease were examined for major malformations of external organs to compare the influence of maternal hyperthyroidism vs. ingestion of methimazole (MMI) during the first trimester on the incidence of congenital malformations. The subjects were divided into four groups according to maternal therapy and thyroid status during the first trimester as follows: (1) infants whose mothers did not receive MMI and were hyperthyroid (Group 1), (2) infants whose mothers did not receive MMI and were euthyroid (Group 2), (3) infants whose mothers received MMI and were hyperthyroid (Group 3) and (4) infants whose mothers received MMI and were euthyroid (Group 4). The prevalence of malformed infants in these four groups was 6.0% (three of 50), 0.3% (one of 350), 1.7% (two of 117) and 0.0% (none of 126), respectively. The incidence in Group 1 was significantly higher than that in Group 2 (P less than 0.01). There was no discernible dose dependency of MMI on the occurrence of malformations. These findings suggest that maternal uncontrolled hyperthyroidism may cause congenital malformations and that the beneficial role of MMI treatment outweighs its teratogenic effect, if any.

Comparison of methimazole and propylthiouracil in patients with hyperthyroidism caused by Graves' disease

CONTEXT

Although methimazole (MMI) and propylthiouracil (PTU) have long been used to treat hyperthyroidism caused by Graves' disease (GD), there is still no clear conclusion about the choice of drug or appropriate initial doses.

OBJECTIVE

The aim of the study was to compare the MMI 30 mg/d treatment with the PTU 300 mg/d and MMI 15 mg/d treatment in terms of efficacy and adverse reactions.

DESIGN, SETTING, AND PARTICIPANTS

Patients newly diagnosed with GD were randomly assigned to one of the three treatment regimens in a prospective study at four Japanese hospitals.

MAIN OUTCOME MEASURES

Percentages of patients with normal serum free T(4) (FT4) or free T(3) (FT3) and frequency of adverse effects were measured at 4, 8, and 12 wk.

RESULTS

MMI 30 mg/d normalized FT4 in more patients than PTU 300 mg/d and MMI 15 mg/d for the whole group (240 patients) at 12 wk (96.5 vs. 78.3%; P = 0.001; and 86.2%, P = 0.023, respectively). When patients were divided into two groups by initial FT4, in the group of the patients with severe hyperthyroidism (FT4, 7 ng/dl or more, 64 patients) MMI 30 mg/d normalized FT4 more effectively than PTU 300 mg/d at 8 and 12 wk and MMI 15 mg/d at 8 wk, respectively (P < 0.05). No remarkable difference between the treatments was observed in patients with initial FT4 less than 7 ng/dl. Adverse effects, especially mild hepatotoxicity, were higher with PTU and significantly lower with MMI 15 mg/d compared with MMI 30 mg/d.

CONCLUSIONS

MMI 15 mg/d is suitable for mild and moderate GD, whereas MMI 30 mg/d is advisable for severe cases. PTU is not recommended for initial use.

Adverse effects of prenatal methimazole exposure

BACKGROUND

A specific phenotype of methimazole (MMI) induced malformations has recently been postulated. MMI embryopathy is characterized by minor dysmorphic features, choanal atresia and/or esophageal atresia, growth retardation, and developmental delay.

METHODS

We prospectively studied the outcome of pregnancy in 241 women counseled by 10 Teratology Information Services (TIS) of the European Network of Teratology Information Services (ENTIS) because of MMI exposure, and compared them with those of 1,089 pregnant women referred to TIS because of exposure to nonteratogenic drugs (control group). Information was obtained by mail or telephone interview.

RESULTS

There was no increase in the general rate of major anomalies or of spontaneous or induced abortions in the MMI-exposed group in comparison with the control group. Two newborns were affected with one of the major malformations that are part of the postulated embryopathy.

CONCLUSIONS

The results of this study indicate that choanal as well as esophageal atresia may have a higher incidence than expected in fetuses exposed to MMI between 3 and 7 gestational weeks. Until further data are available, thyrotoxicosis should be treated with propylthiouracil, as it is apparently safer for use during the fertile period.

Agranulocytosis associated with antithyroid drugs. Effects of patient age and drug dose

The records of all patients with antithyroid drug-related agranulocytosis at two Boston hospitals (Group 1, 14 patients), as well as the published case reports of 36 patients with this syndrome (Group 2) were reviewed. The clinical characteristics of these patients were then compared with those of 50 hyperthyroid patients who had taken antithyroid medication without untoward hematologic reactions (Group 3). The mean ages of patients in Group 1 and Group 2 were significantly greater than that of Group 3 (50.6 +/- 16 years versus 35.7 +/- 13.7 years, p less than 0.001; 46.3 +/- 18.7 years versus 35.7 +/-- 13.7 years, p less than 0.02). By chi-square analysis, the relative risk of developing agranulocytosis in patients over age 40 was 6.4 times that among younger patients (p less than 0.001). The mean doses of methimazole in Group 1 and Group 2 were significantly higher than that in Group 3 (43.8 +/- 9.9 mg/d versus 29.5 +/- 10.4 mg/d, p less than 0.001; 40.7 +/- 15.7 mg/d versus 29.5 +/- 10.4 mg/d, p less than 0.02), with and 8.6-fold increased risk of agranulocytosis with doses greater than 40 mg/d (p less than 0.01). In contrast, the mean doses of propylthiouracil did not differ among the three groups. These data suggest that antithyroid drugs should be administered cautiously to patients over age 40. Because no cases of agranulocytosis were seen with methimazole doses less than 30 mg/d, low-dose methimazole therapy may be safer than high-dose therapy or treatment with conventional doses of propylthiouracil.

Birth defects after early pregnancy use of antithyroid drugs: a Danish nationwide study

INTRODUCTION

Hyperthyroidism in pregnant women should be adequately treated to prevent maternal and fetal complications, but teratogenic effects of antithyroid drug (ATD) treatment have been described. Evidence is still lacking in regard to the safety and choice of ATD in early pregnancy.

OBJECTIVE

Our objective was to determine to which degree the use of methimazole (MMI)/carbimazole (CMZ) and propylthiouracil (PTU) in early pregnancy is associated with an increased prevalence of birth defects.

METHODS

This Danish nationwide register-based cohort study included 817 093 children live-born from 1996 to 2008. Exposure groups were assigned according to maternal ATD use in early pregnancy: PTU (n = 564); MMI/CMZ (n = 1097); MMI/CMZ and PTU (shifted in early pregnancy [n = 159]); no ATD (ATD use, but not in pregnancy [n = 3543]); and nonexposed (never ATD use [n = 811 730]). Multivariate logistic regression was used to estimate adjusted odds ratio (OR) with 95% confidence interval (95% CI) for diagnosis of a birth defect before 2 years of age in exposed versus nonexposed children.

RESULTS

The prevalence of birth defects was high in children exposed to ATD in early pregnancy (PTU, 8.0%; MMI/CMZ, 9.1%; MMI/CMZ and PTU, 10.1%; no ATD, 5.4%; nonexposed, 5.7%; P < .001). Both maternal use of MMI/CMZ (adjusted OR = 1.66 [95% CI 1.35-2.04]) and PTU (1.41 [1.03-1.92]) and maternal shift between MMI/CMZ and PTU in early pregnancy (1.82 [1.08-3.07]) were associated with an increased OR of birth defects. MMI/CMZ and PTU were associated with urinary system malformation, and PTU with malformations in the face and neck region. Choanal atresia, esophageal atresia, omphalocele, omphalomesenteric duct anomalies, and aplasia cutis were common in MMI/CMZ-exposed children (combined, adjusted OR = 21.8 [13.4-35.4]).

CONCLUSIONS

Both MMI/CMZ and PTU were associated with birth defects, but the spectrum of malformations differed. More studies are needed to corroborate results in regard to early pregnancy shift from MMI/CMZ to PTU. New ATD with fewer side effects should be developed.

Methimazole treatment of 262 cats with hyperthyroidism

The efficacy and safety of the antithyroid drug methimazole were evaluated over a 3-year period in 262 cats with hyperthyroidism. In 181 of the cats, methimazole was administered for 7 to 130 days (mean, 27.7 days) as a preoperative preparation for thyroidectomy. The remaining 81 cats were given methimazole for 30 to 1,000 days (mean, 228 days) as sole treatment for the hyperthyroid state. After 2 to 3 weeks of methimazole therapy (10 to 15 mg/d), the mean serum thyroxine (T4) concentration decreased significantly (P less than 0.001) from a pretreatment value of 12.1 micrograms/dl to 2.1 micrograms/dl. The final maintenance dose needed to maintain euthyroidism in the 81 cats that were given methimazole as sole treatment for hyperthyroidism ranged from 2.5 to 20 mg/d (mean, 11.9 mg/d). Clinical side effects developed in 48 (18.3%) cats (usually within the first month of therapy), which included anorexia, vomiting, lethargy, self-induced excoriation of the face and neck, bleeding diathesis, and icterus caused by hepatopathy. Mild hematologic abnormalities developed in 43 (16.4%) cats (usually within the first 2 months of treatment), which included eosinophilia, lymphocytosis, and slight leukopenia. In ten (3.8%) cats, more serious hematologic reactions developed including agranulocytosis and thrombocytopenia (associated with bleeding). These hematologic abnormalities resolved within 1 week after cessation of methimazole treatment. Immunologic abnormalities associated with methimazole treatment included the development of antinuclear antibodies in 52 of 238 (21.8%) cats tested and red cell autoantibodies (as evidenced by positive direct antiglobulin tests) in three of 160 (1.9%) cats tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of graves' disease with antithyroid drugs in the first trimester of pregnancy and the prevalence of congenital malformation

BACKGROUND

Several reports have suggested that propylthiouracil (PTU) may be safer than methimazole (MMI) for treating thyrotoxicosis during pregnancy because congenital malformations have been associated with the use of MMI during pregnancy.

OBJECTIVES

We investigated whether in utero exposure to antithyroid drugs resulted in a higher rate of major malformations than among the infants born to a control group of pregnant women.

METHODS

We reviewed the cases of women with Graves' disease who became pregnant. The pregnancy outcomes of 6744 women were known, and there were 5967 live births. MMI alone had been used to treat 1426 of the women, and 1578 women had been treated with PTU alone. The 2065 women who had received no medication for the treatment of Graves' disease during the first trimester served as the control group. The remaining women had been treated with potassium iodide, levothyroxine, or more than one drug during the first trimester. The antithyroid drugs were evaluated for associations with congenital malformations.

RESULTS

The overall rate of major anomalies in the MMI group was 4.1% (50 of 1231), and it was significantly higher than the 2.1% (40 of 1906) in the control group (P = 0.002), but there was no increase in the overall rate of major anomalies in the PTU group in comparison with the control group (1.9%; 21 of 1399; P = 0.709). Seven of the 1231 newborns in the MMI group had aplasia cutis congenita, six had an omphalocele, seven had a symptomatic omphalomesenteric duct anomaly, and one had esophageal atresia. Hyperthyroidism in the first trimester of pregnancy did not increase the rate of congenital malformation.

CONCLUSIONS

In utero exposure to MMI during the first trimester of pregnancy increased the rate of congenital malformations, and it significantly increased the rate of aplasia cutis congenita, omphalocele, and a symptomatic omphalomesenteric duct anomaly.

Dissimilar hepatotoxicity profiles of propylthiouracil and methimazole in children

BACKGROUND

The antithyroid drugs propylthiouracil and methimazole were introduced for clinical use about 60 yr ago and are estimated to be used in more than 6000 children and adolescents per year in the United States. Over the years that these medications have been used, reports of adverse events involving hepatotoxicity have appeared. To date, there has not been a systematic and comparative evaluation of the adverse events associated with antithyroid drug use.

OBJECTIVE

Our objective was to assess safety and hepatotoxicity profiles of propylthiouracil and methimazole by age in the U.S. Food and Drug Administration's Adverse Event Reporting System (AERS).

DESIGN

We used the multi-item gamma-Poisson shrinker (MGPS) data mining algorithm to analyze more than 40 yr of safety data in AERS. MGPS uses a Bayesian model to calculate adjusted observed to expected ratios [empiric Bayes geometric mean (EBGM) values] for every drug-adverse event combination in AERS, focusing on hepatotoxicity events.

RESULTS

MGPS identified higher-than-expected reporting of severe liver injury in pediatric patients treated with propylthiouracil but not with methimazole. Propylthiouracil had a high adjusted reporting ratio for severe liver injury (EBGM 17; 90% confidence interval = 11.5-24.1) in the group less than 17 yr old. The highest EBGM values for methimazole were with mild liver injury in the group 61 yr and older [EBGM 4.8 (3.3-6.8)], which consisted of cholestasis. Vasculitis was also observed for propylthiouracil in children and adolescents, reaching higher EBGM values than hepatotoxicity signals.

CONCLUSIONS

MGPS detects higher-than-expected reporting of severe hepatotoxicity and vasculitis in children and adolescents with propylthiouracil but not with methimazole.

Treatment of hyperthyroidism in pregnancy and birth defects

CONTEXT

Clinical hyperthyroidism is not uncommon in pregnancy, with a reported prevalence of 0.1 to 0.4%. The available antithyroid drugs are propylthiouracil and methimazole/carbimazole.

OBJECTIVES

In this report we examined the association of both drugs with congenital malformations using data from the International Clearinghouse for Birth Defects Surveillance and Research.

DESIGN

The study used a case-affected control analysis and included 18,131 cases with malformations and reported first-trimester exposure to medication. A total of 127 subjects were born to mothers with known first-trimester antithyroid drug exposure.

RESULTS

Among the 52 groups of malformations that were analyzed, situs inversus ± dextrocardia, isolated unilateral kidney a/dysgenesis, and cardiac outflow tract defects were associated with prenatal exposure to propylthiouracil based on three, two, and five cases, respectively. Prenatal exposure to methimazole/carbimazole was significantly associated with choanal atresia, omphalocele, and total situs inversus ± dextrocardia (P < 0.01).

CONCLUSIONS

Further studies are required to exhaustively evaluate the associations between propylthiouracil and birth defects because of the low number, the lack of biological plausibility, and the possibility of underdiagnosis. Association between methimazole/carbimazole exposure and omphalocele and choanal atresia is consistent with previous reports and definitely suggests that these malformations could be part of a specific, even if rare, embryopathy.

Review of antithyroid drug use during pregnancy and report of a case of aplasia cutis

Thioamide therapy has improved the outcome of pregnancies complicated by maternal hyperthyroidism, without long-term effects on cognitive and somatic development. However, there remain questions concerning whether these drugs, especially methimazole (MMI), may be associated with aplasia cutis congenita (ACC) and how best to avoid impairment of fetal thyroid function during their use. We report an example of ACC and review the relevant literature. We conclude that there is insufficient evidence either to establish or eliminate a direct causal relationship between ACC and MMI use. Since propylthiouracil is an equally effective antithyroid agent and has not been associated with ACC, it is the preferred thioamide for hyperthyroidism during pregnancy. Our review also indicates that impairment of neonatal thyroid function may be minimized by using a thioamide dose that is just sufficient to maintain the maternal serum free thyroxine concentration in the high normal or slightly thyrotoxic range.

Effect of long-term continuous methimazole treatment of hyperthyroidism: comparison with radioiodine

OBJECTIVE

To investigate the long-term effects of continuous methimazole (MMI) therapy.

DESIGN AND METHODS

Five hundred and four patients over 40 years of age with diffuse toxic goiter were treated with MMI for 18 months. Within one year after discontinuation of MMI, hyperthyroidism recurred in 104 patients. They were randomized into 2 groups for continuous antithyroid and radioiodine treatment. Numbers of occurrences of thyroid dysfunction and total costs of management were assessed during 10 years of follow-up. At the end of the study, 26 patients were still on continuous MMI (group 1), and of 41 radioiodine-treated patients (group 2), 16 were euthyroid and 25 became hypothyroid. Serum thyroid and lipid profiles, bone mineral density, and echocardiography data were obtained.

RESULTS

There was no significant difference in age, sex, duration of symptoms and thyroid function between the two groups. No serious complications occurred in any of the patients. The cost of treatment was lower in group 1 than in group 2. At the end of 10 years, goiter rate was greater and antithyroperoxidase antibody concentration was higher in group 1 than in group 2. Serum cholesterol and low density lipoprotein-cholesterol concentrations were increased in group 2 as compared with group 1; relative risks were 1.8 (1.12-2.95, P<0.02) and 1.6 (1.09-2.34, P<0.02) respectively. Bone mineral density and echocardiographic measurements were not different between the two groups.

CONCLUSION

Long-term continuous treatment of hyperthyroidism with MMI is safe. The complications and the expense of the treatment do not exceed those of radioactive iodine therapy.

Allele specificity of structural requirement for peptides bound to HLA-DRB1*0405 and -DRB1*0406 complexes: implication for the HLA-associated susceptibility to methimazole-induced insulin autoimmune syndrome

Self-peptides bound to HLA-DR4 (DRA-DRB1*0405 complex) were eluted from the purified DR4 complex, fractionated on reverse-phase HPLC, and subjected to NH2-terminal sequencing. Seven independent sequences were obtained, and all putative peptides synthesized bound to DRB1*0405 as well as DRB1*0406 complex, which differ only at DR beta residues 37, 57, 74, and 86. Binding assay using analogue peptides of a DR4 binder GSTVFDNLPNPE revealed that FxxLxN is an important anchor motif necessary for binding (where x is any amino acid), which was common to DRB1*0405 and 0406. Determination of the binding affinity of 60 synthetic AAFAALANAA-based analogue peptides showed that substituting F to W or C; L to F, W, or Y; and N to Q or S on AAFAALANAA changed the affinity substantially between DRB1*0405 and DRB1*0406. It is noteworthy that all patients with methimazole-induced insulin autoimmune syndrome are positive for DRB1*0406 and negative for DRB1*0405. Interestingly, the quantitative structural motif identified in this study predicted that 8TSICSLYQLE17 of human insulin alpha chain may bind specifically to DRB1*0406 using its 10IxxLxQ15 motif. Indeed, DRB1*0406 complex bound 8TSICSLYQLE17 with a high affinity, and in striking contrast, DRB1*0405 complex did not. Furthermore, a short-term T cell line specific to human insulin established from a DRB1*0406-bearing individual did show reactivity with a peptide fragment containing the 10IxxLxQ15 motif. Although this fragment probably exists at a very low level under normal physiological conditions due to the disulfide bond between flanking cysteine residues (6Cys-11Cys), a reducing compound such as methimazole may cleave the disulfide bond in vivo and allow DR alpha-DRB1*0406 complex on antigen-presenting cells to bind much of the linear fragment of insulin alpha chain, which may lead to the activation of self-insulin-specific T-helper cells.

Analysis of 754 cases of antithyroid drug-induced agranulocytosis over 30 years in Japan

BACKGROUND

Agranulocytosis is a rare but serious complication of antithyroid drug (ATD) therapy. Characteristics of agranulocytosis have been reported in only a small number of patients.

METHOD

We studied 754 cases of ATD-induced agranulocytosis reported over 30 years. The age distribution and sex ratio were compared with those in 12 503 untreated Graves' patients at Kuma Hospital. The annual number of new Graves' patients in Japan was estimated from the Japan Medical Data Center Data Mart-Pharmacovigilance health insurance receipt database.

RESULTS

Agranulocytosis developed within 90 days after starting ATD therapy in most patients (84.5%). The methimazole dose given at onset was 25.2 ± 12.8 mg/d (mean ± SD). The mean age was 43.4 ± 15.2 years, and the male to female ratio was 1:6.3. When compared with patients at Kuma Hospital, patients with agranulocytosis were older (P < .001) and more females (P < .0001). Of 211 patients with more than 1 granulocyte measurement before onset, 131 (62%) showed normal counts (>1000/μL) within 2 weeks before onset, demonstrating real sudden onset of agranulocytosis. In contrast, some of the 20 patients with more than 4 measurements showed gradual decreases in granulocyte counts. Analysis of physician reports for 30 fatal cases revealed that some deaths might have been prevented. The number of new Graves' patients treated with ATD was estimated at about 35 000 per year, and the incidence rate of agranulocytosis was 0.1% to 0.15% in Japan.

CONCLUSION

This is the largest study of agranulocytosis. Agranulocytosis tends to occur abruptly within 3 months after initiation of ATD therapy, although it develops gradually in some patients. Providing every patient with sufficient information on agranulocytosis is critical.

Antineutrophil cytoplasmic antibody (ANCA)-associated autoimmune diseases induced by antithyroid drugs: comparison with idiopathic ANCA vasculitides

Clinical and serological profiles of idiopathic and drug-induced autoimmune diseases can be very similar. We compared data from idiopathic and antithyroid drug (ATD)-induced antineutrophil cytoplasmic antibody (ANCA)-positive patients. From 1993 to 2003, 2474 patients were tested for ANCA in the Laboratory for Allergy and Clinical Immunology in Belgrade. Out of 2474 patients, 72 (2.9%) were anti-proteinase 3 (PR3)- or anti-myeloperoxidase (MPO)-positive and their clinical and serological data were analyzed. The first group consisted of ANCA-associated idiopathic systemic vasculitis (ISV) diagnosed in 56/72 patients: 29 Wegener's granulomatosis (WG), 23 microscopic polyangiitis (MPA) and four Churg-Strauss syndrome. The second group consisted of 16/72 patients who became ANCA-positive during ATD therapy (12 receiving propylthiouracil and four receiving methimazole). We determined ANCA and antinuclear (ANA) antibodies by indirect immunofluorescence; PR3-ANCA, MPO-ANCA, anticardiolipin (aCL) and antihistone antibodies (AHA) by ELISA; and cryoglobulins by precipitation. Complement components C3 and C4, alpha-1 antitrypsin (α1 AT) and C reactive protein (CR-P) were measured by nephelometry. Renal lesions were present in 3/16 (18.8%) ATD-treated patients and in 42/56 (75%) ISV patients (p <0.001). Skin lesions occurred in 10/16 (62.5%) ATD-treated patients and 14/56 (25%) ISV patients (p <0.01). ATD-treated patients more frequently had MPO-ANCA, ANA, AHA, aCL, cryoglobulins and low C4 (p <0.01). ISV patients more frequently had low α1 AT (p = 0.059) and high CR-P (p <0.001). Of 16 ATD-treated patients, four had drug-induced ANCA vasculitis (three MPA and one WG), while 12 had lupus-like disease (LLD). Of 56 ISV patients, 13 died and eight developed terminal renal failure (TRF). There was no lethality in the ATD-treated group, but 1/16 with methimazole-induced MPA developed pulmonary-renal syndrome with progression to TRF. ANCA-positive ISV had a more severe course in comparison with ATD-induced ANCA-positive diseases. Clinically and serologically ANCA-positive ATD-treated patients can be divided into two groups: the first consisting of patients with drug-induced WG or MPA which resemble ISV and the second consisting of patients with LLD. Different serological profiles could help in the differential diagnosis and adequate therapeutic approach to ANCA-positive ATD-treated patients with symptoms of systemic disease.

Drug-induced immunological neutropenia

Antineutrophil antibody capable of opsonising normal neutrophils was detected in the sera of 16 neutropenic patients receiving various drugs. A single drug was involved in 10 cases, multiple medication in 6. 4 patients received semisynthetic penicillins, 8 some form of antimicrobial, and 2 antithyroid agents. Neutrophil counts rose, and antineutrophil antibody activity declined or disappeared, after drug therapy was stopped. Opsonisation related to the semisynthetic penicillins was independent of complement but dependent on drug concentration. Complement-dependent opsonic activity was demonstrated in 2 patients (1 receiving methimazole and 1 receiving multiple medication) and in the patient receiving methimazole this activity was shown to reside in the IgM serum-fraction. In another patient receiving multiple drugs, a complement-independent IgG antibody was demonstrated.

Antithyroid drug-induced hematopoietic damage: a retrospective cohort study of agranulocytosis and pancytopenia involving 50,385 patients with Graves' disease

CONTEXT

Although antithyroid drug (ATD)-induced hematopoietic damage is a significant concern, it has not been comprehensively investigated.

OBJECTIVE

Our objective was to describe the clinical features of ATD-induced hematopoietic damage.

DESIGN AND SETTING

This was a retrospective cohort study in Tokyo, Japan.

PATIENTS

Between January 1983 and December 2002, 50,385 patients at Ito Hospital were diagnosed with Graves' disease. We retrospectively reviewed their medical, pathological, and laboratory records between January 1983 and December 2010.

MAIN OUTCOME

Incidence and clinical features of ATD-induced agranulocytosis and pancytopenia were evaluated.

RESULTS

Of 55 patients with documented hematopoietic damage, 50 had agranulocytosis and 5 had pancytopenia. All of them received ATD, either methimazole (n = 51) or propylthiouracil (n = 4). Median intervals between initiation of ATD therapy and the onset of agranulocytosis and pancytopenia were 69 d (range, 11-233 d) and 41 d (range, 32-97 d), respectively. Either anemia or thrombocytopenia was also documented in seven of the 50 patients with agranulocytosis. Agranulocytosis was the first manifestation of hematopoietic damage in four of the five patents with pancytopenia. Hematopoietic damage recovered with supportive measures including granulocyte colony-stimulating factor (n = 37), steroids (n = 10), and other supportive measures (n = 8) in 54 patients, whereas the remaining patient died of complications from infection. This study failed to identify the risk factors for ATD-induced hematopoietic damage.

CONCLUSIONS

This study showed that ATD cause hematopoietic changes, which are occasionally severe and potentially fatal. The pathogenesis of agranulocytosis and pancytopenia might overlap, and additional studies are warranted to clarify this and to establish an optimal treatment strategy.

Methimazole-induced agranulocytosis in patients with Graves' disease is more frequent with an initial dose of 30 mg daily than with 15 mg daily

BACKGROUND

Antithyroid drugs (ATDs) are prescribed as the initial therapy for the majority of patients with Graves' disease in many areas of the world. Although, it is well known that agranulocytosis is one of the most serious side effects of ATDs, there has not yet been any conclusive evidence that the prevalence of agranulocytosis induced by ATDs is dose related. This study was performed to determine if the prevalence of agranulocytosis is different depending on the starting dosage of ATDs in patients with Graves' disease.

METHODS

Until 1996, we had typically prescribed 30 mg/d of methimazole (MMI) as the initial dosage for the treatment of Graves' disease at our institution. We changed the initial MMI dosage to 15 mg/d as a general rule in 1997. As a consequence, we acquired two groups of patients with Graves' disease who received different dosages of MMI. We retrospectively compared the prevalence of MMI-induced agranulocytosis in patients who received 15 mg/d of MMI to those who received 30 mg/d of MMI.

RESULTS

There were 2087 subjects treated with 30 mg/d of MMI and 2739 treated with 15 mg/d of MMI. The prevalence of agranulocytosis in the 30 mg/d group was significantly higher than in the 15 mg/d group (0.814% vs. 0.219%, respectively, p < 0.01). The prevalence of agranulocytosis plus neutropenia in the 30 mg/d group was also significantly higher than in the 15 mg/d group (1.581% vs. 0.474%, respectively, p < 0.001).

CONCLUSIONS

It is very likely that MMI-induced agranulocytosis occurs with a larger dosage of MMI and is dose related. Considering both the effectiveness and the risk of serious side effects, we recommend 15 mg/d of MMI as the starting dosage for the treatment of Graves' disease.

Methimazole-induced hepatotoxicity

OBJECTIVE

To present the case of a patient with Graves' hyperthyroidism in whom treatment with methimazole led to severe cholestasis.

METHODS

A detailed case report and an overview of previously published cases of methimazole- and carbimazole-induced hepatotoxicity, found in a MEDLINE search with use of methimazole, carbimazole, thionamides and antithyroid agents as subject headings, are provided.

RESULTS

In a 36-year-old woman with severe hyperthyroidism, treatment with methimazole (20 mg twice daily) was initiated. Nineteen days later, pruritus, scleral icterus, dark urine, and abdominal discomfort prompted discontinuation of the therapy. Laboratory investigations and abdominal ultrasonography showed findings consistent with a cholestatic reaction to methimazole. Recovery was slow but complete. Of the 30 previously published cases of hepatotoxicity related to treatment with methimazole or carbimazole in which the nature of the hepatic injury was described, 19 were also cholestatic.

CONCLUSION

Physicians should be aware that thionamide drugs can be associated with hepatotoxicity. Analysis of the known cases suggests that older age of the patient and higher dose of the drug are risk factors for cholestatic injury.