Incidence of a positive direct coombs test in patients on alpha-methyldopa

Methyldopa-induced pancreatitis

An acute febrile illness associated with gastrointestinal upset developed in a patient within one week after starting treatment with methyldopa. The illness was characterized by prompt subsidence of symptoms when the patient withdrew therapy secondary to gastrointestinal upset, and recrudescence of symptoms when methyldopa therapy was reinitiated. This was associated with hyperamylasemia, hyperlipasemia, hyperpyrexia, and epigastric pain, both on admission to the hospital and upon rechallenge with methyldopa. Although gastrointestinal upset has been reported as an untoward side effect of methyldopa, this is the first report to our knowledge of documented methyldopa-induced hyperamylasemia and hyperlipasemia secondary to pancreatitis.

Critical re-examination of the specificity of auto-anti-Rh antibodies in patients with a positive direct antiglobulin test

Forty-eight autoantibodies with apparent 'simple' anti-Rh specificity (anti-e, -E, -c, -D, -C, -Ce, -G), have been studied by means of multiple absorption tests. The finding that 34 (70.8%) of these antibodies could bind to red blood cells lacking the antigens that the antibodies appeared to define, indicated that the antibodies had different specificities than seemed to be the case in initial antibody identification tests. Those autoantibodies that at first appeared to be directed against the Rh antigens e, E or c, most often had anti-Hr or anti-Hro specificity. These data explain why some apparent anti-Rh autoantibodies can be eluted from the red blood cells of patients negative for the antigens that the antibodi:s appear to define. However, they also illustrate that the phenomenon of autoantibodies mimicking specificities that they do not possess is common in patients positive for the antigens against which their autoantibodies appear to be directed. An explanation for the mode of action of these autoantibodies in complexing with the Rh agglutinogen is proposed, and the significance of the antibodies in transfusion therapy is considered.

Treatment of hypertension in pregnancy with methyldopa: blood pressure control and side effects

A total of 242 women with moderate hypertension in pregnancy completed a controlled trial of methyldopa (Aldomet). The hypotensive effect of methyldopa was similar to its action in non-pregnant individuals and greatly reduced the frequency of severe hypertension occurring antenatally and in labour. As pregnancy advanced, an increasing daily dose of methyldopa was needed and there was a greater use of additional hypotensive therapy. Seventeen (14-5 per cent) women assigned to methyldopa had to be transferred to another drug or had to stop treatment completely because of minor side effects, of which the commonest were lack of energy and dizziness. No serious side effects were encountered. Nine per cent of the untreated women developed severe hypertension which required treatment later in their pregnancies. Six weeks after delivery, nearly all the patients were able to stop treatment.

Methyldopa binding to cells in culture

Cells from a rat hepatoma grown in culture were found to activate methyldopa to intermediates which are bound irreversibly to cellular proteins. The binding reaction was not inhibited by superoxide dismutase or allopurinol, but was strongly inhibited by ascorbic acid and glutathione. Methyldopa, paracetamol and furosemide were not mutagenic in the Salmonella/mammalian-microsome mutagenicity test.

Anti-Wrb, and other autoantibodies responsible for positive direct antiglobulin tests in 150 individuals

Eluates from the red blood cells (and sera whenever free autoantibody was present) of 150 individuals with positive direct antiglobulin tests, have been studied for antibody specificity. Of 87 patients with AIHA, 64 had autoantibodies reacting with all red cell samples including Rhnu11. Of these 64 anti-d1 autoantibodies, two were, and 32 contained, auto-anti-Wrb. Of 33 patients being treated with alphamethyldopa, who had developed positive direct antiglobulin tests, 23 had anti-d1 autoantibodies four of which contained auto-anti-Wrb. Of 30 haematologically normal donors with positive direct antiglobulin tests, 23 had anti-d1 autoantibodies, two of which were, and six of which contained, auto-anti-Wrb. The full specificities of autoantibodies, other than anti-Wrb and anti-d1, in the 150 patients are described, as are the natures of the protein red cell coatings that caused the positive direct antiglobulin tests. The presence of free serum autoantibody as a correlate of the three clinical conditions is reported. Several observations on auto-anti-Wrb are documented. The antibody can cause gross red cell destruction in vivo, but can be benign on other occasions; it occurs with approximately the same frequency in AIHA patients and "normal" donors with positive direct antiglobulin tests, but in fewer patients with alphamethydopa induced positive direct antiglobulin tests; it does not activate complement in vivo; and finally it may eventually provide a clue to the aetiology of AIHA.

Methyldopa Hepatitis. A report of six cases and review of the literature

Six cases of methyldopa hepatitis, including two in which the patients died are reported; and 77 cases from the literature are reviewed. Patients in whom severe hepatotoxic reactions to methyldopa develop usually complain of prodromal symptoms typical of hepatitis, often with fever, one to four weeks after therapy is initiated. Jaundice, when it occurs, is usually manifest within three months. Asymptomatic, transient elevations of serum transaminase levels may occur in patients receiving methyldopa. However, since the clinical and histologic features of hepatic injury from methyldopa are indistinguishable from viral hepatitis, it is suggested that the incidence of this iatrogenic disease is higher than generally appreciated. Serum transaminase levels should be determined at the initiation of therapy with methyldopa and four weeks later. Moreover, any patient who has unexplained fever or the prodromal symptoms of hepatitis should undergo liver chemistry studies immediately.

Drug-induced antinuclear antibodies and lupus syndromes

Drugs capable of triggering the onset of systemic lupus erythematosus may be divided into those that do so by pharmacological properties of their own and those that do so by eliciting allergic reactions which bring about lupus. Drugs in the first group vary in their potency to activate lupus. They all elicit antinuclear antibodies in the majority of patients who receive them but they only cause lupus in a small percentage of patients. This dichotomy suggests that a predisposition is required for the development of lupus upon intake of these drugs. The mechanism whereby these drugs elicit antinuclear antibodies seems to relate to coupling to and/or modification of, nuclear antigens. The patterns of antinuclear antibodies elicited by these drugs in individuals who receive them correlate well with their known reactivity with various nuclear antigens.

Retroperitoneal fibrosis during treatment with methydopa

Retroperitoneeal fibrosis (R.P.F.) and a positive direct Coombs test developed in a patient who had received 1.4 kg. of alpha-methyldopa over a period of 5 years. Immunofluorescence microscopy demonstrated deposits of IgG, IgM, and IgA on the collagen fibres of the R.P.F. Biopsy speciments of the temporal artery, the right kidney, and the R.P.F. did not show signs of general arterial disease on light, immunofluorescence, and electron microscopy. Drugs which provoke autoimmunisation and interfere with nervous transmission are known to induce deposition of collagen or R.P.F. This suggests that R.P.F. in this patient was probably caused by alpha-methydopa.

Adverse reactions and interactions limiting the use of antihypertensive drugs

One major problem in the management of hypertensive patients is their lack of compliance with therapeutic regimens. Some of the problem with compliance is due to side effects of the drugs being used. Additionally, drug resistance may be related to interactions of antihypertensive drugs with other prescription and nonprescription drugs. By classifying drugs into common modes of action, common side effects can be predicted. However, each drug has its own spectrum of other side effects which can be dose-limiting. Most of the side effects are extensions of the pharmacologic actions of these drugs, and only relatively rarely is an allergic reaction a problem. Drug interactions can be important in explaining some side effects or drug resistance. A knowledge of the pharmacology of the antihypertensive drugs allows the physician to predict, in many cases, the possibility of an interaction and, indeed, can allow the use of interactions to advantage as with combinations of vasodilators and beta adrenergic blocking drugs. Until such time as the perfect antihypertensive drug is discovered, most patients can be managed satisfactorily with minimal side effects by judicious combination of available drugs and avoiding drugs which interact to cause more side effects or decrease the antihypertensive effects.

Ultrastructural mapping of methyldopa and anti-D IgG erythrocyte antigen receptors

The ultrastructural distribution pattern and site density of alpha-methyldopa immunoglobin G (alpha-MD IgG) on the red cell membrane was observed and compared with that of anti-D IgG, with ferritin-conjugated rabbit anti-human IgG and [125I]anti-D. alpha-MD IgG binds to all common types of human red cells, both Rho (D) positive and negative, to give a random, aperiodic distribution pattern grossly indistinguishable from the red cell D receptor site pattern. alpha-MD IgG inhibits the binding of [125I]anti-D to D-positive red cells when the reaction is controlled with respect to total reaction volume, ionic strength, and the appropriate concentrations of the two IgG reactants. To determine if a alpha-MD IgG binds to the D-antigen receptor, D-positive red cells were sensitized with alpha-MD and [125I]anti-D IgG spearately and with both IgG preparations. The cell-bound radioactivity served to identify what proportion of the total ferritin-labeled IgG sites were due to anti-D. With nonsaturating concentrations of anti-D the number of IgG sites observed was equal to the sum of the sites found when the red cell was sensitized separately with alpha-MD and anti-D IgG. With saturating concentrations of anti-D there was a reduction in the expected number of IgG sites, indicating that alpha-MD IgG was excluded from binding. There was no comparable interaction of alpha-MD IgG and anti-D IgG when D-negative red cells were used. The results obtained indicate that alpha-MD IgG does not bind to the D antigen. The interaction between alpha-MD IgG and anti-D IgG for binding sites on the red cell membrane may be due to the close physical proximity of the two receptors, so as to produce steric hindrance in binding of the two IgG preparations when both are present. The alpha-MD IgG receptor appears to be a part of the Rh antigen complex that occurs in both D-positive and D-negative red cells and probably contains receptors for other types of warm-antibody immune hemolytic anemias.

Drug-induced immune hemolytic anemia

Drug administration causes from 16 to 18 per cent of cases of acquired immune hemolytic anemia. The pathogenesis of erythrocyte sensitization by drug-related antibody with or without fixation of complement is variable, and there is a relationship between the responsible drug, the mechanism of red cell sensitization, clinical manifestations and laboratory methods of diagnosis. Drugs such as phenacetin and quinidine form a complex with the antidrug antibody, and the immune complex attaches to red cells usually fixing complement and causing acute intravascular hemolysis. Other drugs (e.g., penicillins), when given in large doses, coat normal red cells in vivo and in some patients a high titer IgG anti-drug antibody develops which reacts with the coated cells. Hemolytic anemia may develop with red cell destruction being primarily extravascular. Cephalosporins cause positive direct antiglobulin tests in a small percentage of patients either by the same mechanism as penicillins or by modification of the red cell membrane leading to nonimmunologic absorption of serum proteins. Hemolytic anemia has been reported only rarely. A few drugs (notably alpha methyldopa) cause the development of autoimmune hemolytic anemia. Knowledge of clinical manifestations and laboratory aids to diagnosis is necessary to distinguish immunohematologic abnormalities caused by drugs from other causes.

A complication of alpha methyldopa therapy

A case is presented as a complication of long-term alpha methyldopa (“Aldomet”) therapy. The complication was the development of an antibody resulting in a positive direct Coombs reaction and consequent difficulty in cross-matching blood.

Raised serum IgG levels in hypertension

Serum IgG levels were significantly higher in 118 severely hypertensive patients compared with a group of 163 normotensive blood donors, matched for age and sex. Serum IgA and IgM were the same in both groups. Raised levels of serum IgG were found in patients who had never been treated for hypertension, as well as in those who were treated with methyldopa or other hypotensive drugs.It is suggested that the raised levels of serum IgG may be an index of vascular damage induced by hypertension.