The influence of uremia on pharmacokinetics and protein binding of prednisolone

Adrenal Insufficiency Associated With Empty Sella Syndrome and Steroid Malabsorption Complicated With Septic Shock Due to Post-transplant Pyelonephritis: A Case Report

Renal transplant recipients are immunocompromised and predisposed to develop hyponatremia because they are exposed to immunological, infectious, pharmacological, and oncologic disorders. A 61-year-old female renal transplant recipient was admitted with diarrhea, anorexia, and headache for about a week during the tapering of oral methylprednisolone for chronic renal allograft rejection. She also presented hyponatremia and was suspected to have secondary adrenal insufficiency based on a low plasma cortisol level of 1.9 μg/dL and a low adrenocorticotropic hormone level of 2.6 pg/mL. Brain magnetic resonance imaging to assess the hypothalamic-pituitary-adrenal axis revealed an empty sella. She also developed septic shock and disseminated intravascular coagulation due to post-transplant pyelonephritis. She had reduced urine output and underwent hemodialysis. Both plasma cortisol and adrenocorticotropic hormone levels were relatively low (5.2 μg/dL and 13.5 pg/mL, respectively), which also suggested adrenal insufficiency. She was treated with hormone replacement therapy and antibiotics, successfully recovered from septic shock, and was withdrawn from dialysis. In empty sella syndrome, the somatotropic and gonadotropic axis are the most affected, followed by the thyrotropic and corticotropic axis. She did not present these abnormalities, which may suggest that empty sella syndrome is a separate pathology, and the axis suppression had occurred due to long-term steroid treatment. Diarrhea due to cytomegalovirus colitis might have induced steroid malabsorption and manifested adrenal insufficiency. Secondary adrenal insufficiency should be investigated as a cause of hyponatremia. It should always be borne in mind that diarrhea during oral steroid treatment may cause adrenal insufficiency associated with steroid malabsorption.

Mania after long-term treatment with daily 10 mg prednisolone

Background

High-dose corticosteroids may be accompanied by central nervous system side-effects, including psychiatric disorders. These psychiatric disorders tend to appear relatively early in treatment. We report an unusual case of mania after long-term administration of a small dose of prednisolone.

Case Presentation

A patient was treated for relapsed Crohn's disease with a small dose of prednisolone (10 mg/day). After 6 months, she became severely manic. There was no family history of psychiatric disorders. The mania was resistant to olanzapine and sodium valproate, but improved with the reduction of the prednisolone dose. Prednisolone was tapered off while confirming with the gastroenterologist that there was no flare-up of Crohn's disease. She is now off prednisolone and is doing well, with no outbreaks of Crohn's disease or manic episodes.

Conclusion

This case of severe mania after 6 months of low-dose prednisolone is unusual. Physicians should be aware that even small doses of long-term prednisolone may cause the emergence of severe mania.

Intra-articular glucocorticoid injections and their effect on hypothalamic-pituitary-adrenal (HPA)-axis function

The use of intra-articular (IA) glucocorticoids for reducing pain and inflammation in patients with osteoarthritis, rheumatoid arthritis, and other inflammatory arthropathies is widespread among primary care physicians, specialists, and non-specialists in the United States. Injectable glucocorticoids have anti-inflammatory and analgesic properties which can be effective in improving clinical parameters such as pain, range of motion, and quality of life. After injection into the IA space, glucocorticoids may be systemically absorbed; the degree of absorption can depend on the size of the joint injected, the injectable glucocorticoid preparation used, the dosage, and the frequency of the injection. The adverse effects of intra-articular glucocorticoid injections (IAGC) can often be overlooked by both the patient and physicians who administer them, in particular the potential deleterious effect on the hypothalamic-pituitary-adrenal (HPA)-axis which can result in adrenal suppression and/or iatrogenic Cushing syndrome. In this paper we provide an overview on the often under-recognized effects of IAGC on HPA-axis function.

Cellular pharmacodynamics of immunosuppressive drugs for individualized medicine

The therapeutic effects of immunosuppressive drugs are known to deviate largely between patients, but efficient strategies for the differentiation of patients who show clinical resistance to immunosuppressive therapies have not been established. Accordingly, a considerable number of patients receive treatment with immunosuppressive drugs despite the onset of serious side effects and poor responses. Cellular pharmacodynamics of immunosuppressive drugs in vitro using peripheral lymphocytes derived from each patient, an attractive way to distinguish resistant patients, is respected and has been applied to the carrying out of individualized immunosuppressive therapy. In this article, I summarize experimental procedures for assaying immune cell responses to immunosuppressive drugs in vitro, and highlight the relationship between cellular sensitivity to immunosuppressive drugs and the therapeutic efficacy of drugs in organ transplantation and several immunological disorders. I will also overview the molecular mechanisms and genetic bases for cellular and clinical resistance to immunosuppressive drugs. Lastly, the future clinical prospects for the application of in vitro drug sensitivity tests for "patient-tailored" immunosuppressive therapies are discussed.

Pharmacokinetics and pharmacodynamics of systemically administered glucocorticoids

Glucocorticoids have pleiotropic effects that are used to treat diverse diseases such as asthma, rheumatoid arthritis, systemic lupus erythematosus and acute kidney transplant rejection. The most commonly used systemic glucocorticoids are hydrocortisone, prednisolone, methylprednisolone and dexamethasone. These glucocorticoids have good oral bioavailability and are eliminated mainly by hepatic metabolism and renal excretion of the metabolites. Plasma concentrations follow a biexponential pattern. Two-compartment models are used after intravenous administration, but one-compartment models are sufficient after oral administration.The effects of glucocorticoids are mediated by genomic and possibly nongenomic mechanisms. Genomic mechanisms include activation of the cytosolic glucocorticoid receptor that leads to activation or repression of protein synthesis, including cytokines, chemokines, inflammatory enzymes and adhesion molecules. Thus, inflammation and immune response mechanisms may be modified. Nongenomic mechanisms might play an additional role in glucocorticoid pulse therapy. Clinical efficacy depends on glucocorticoid pharmacokinetics and pharmacodynamics. Pharmacokinetic parameters such as the elimination half-life, and pharmacodynamic parameters such as the concentration producing the half-maximal effect, determine the duration and intensity of glucocorticoid effects. The special contribution of either of these can be distinguished with pharmacokinetic/pharmacodynamic analysis. We performed simulations with a pharmacokinetic/pharmacodynamic model using T helper cell counts and endogenous cortisol as biomarkers for the effects of methylprednisolone. These simulations suggest that the clinical efficacy of low-dose glucocorticoid regimens might be increased with twice-daily glucocorticoid administration.

Update on systemic glucocorticosteroids in dermatology

Although dermatology now has the most extensive group of systemic medications available for the treatment of skin diseases at any time, GCSs remain the most important agents for managing inflammatory disorders. It is important that the dermatologist have a broad knowledge of guidelines for clinical use, pharmacology, and adverse effects of these drugs. Acute and chronic side reactions should be well recognized. An understanding of the HPA axis and reasons for administering GCSs in different ways is of great value. A good medical history should be taken on any patient treated with GCSs, including knowledge of conditions that would make GCSs inadvisable and other concomitant systemic medications that might produce drug interactions. During the course of therapy, physical examination should include all systems pertinent to side effects caused by these agents, including frequent evaluations of weight and blood pressure. Blood chemistries should be performed on a regular basis, including glucose, electrolytes, and serum lipids. Osteoporosis is one of the most significant adverse affects to be evaluated, with bone mineral density studies recommended on an annual basis for persons continuing on GCS therapy. If hip or other joint pain develops, MR imaging is the most specific and sensitive radiologic examination for evaluating the possibility of osteonecrosis. An ophthalmology examination should be performed every 6 to 12 months to detect early cataract or glaucoma development. Any early signs of infection should be evaluated by appropriate smears, wet preparations, and cultures. Many other studies, including gastrointestinal and pulmonary examinations, may be dictated by specific acute situations. It is important to begin early prevention of the bone loss that occurs with GCS-induced osteoporosis. The 1996 guidelines of the American College of Rheumatology, including adequate calcium and vitamin D intake, should be followed. Hormonal replacement, a bisphosphonate, calcitonin, or a thiazide diuretic may be indicated. Restriction of sodium in the diet is important, as well as adequate potassium intake. The diet should be low in saturated fat and calories and should be high in vegetable protein. Because osteoporosis is so prevalent with GCSs, keeping the patient as active as possible with mild-to-moderate exercise is important. Whenever possible, exposure to persons with infectious processes should be avoided, and proper treatment should be instituted at the initial signs of systemic or cutaneous infection. Oral doses of GCSs are best taken with food to prevent gastrointestinal irritation, and agents for gastric acidity occasionally may be indicated. Significant trauma should be prevented, as should severe exposure to the sun. Many situations may call for consultation with other medical or surgical subspecialists. The patient must be aware of the importance of regular physician evaluations and reporting of any adverse effects while on long-term GCSs. A good relationship and understanding between the patient and physician are vital in minimizing potential problems from these agents. If the dermatologist maintains the proper guidelines of care, patients on GCSs have the highest benefits and lowest risks possible.

Clinical pharmacokinetics of prednisone and prednisolone

The growth of knowledge in the field of the pharmacokinetics of prednisolone/prednisone has been slow for several reasons. First, convenient and specific methods for measuring these steroids only became available with the development of high performance liquid chromatographic methods. Secondly, prednisolone is nonlinearly bound to transcortin and albumin: since the unbound concentrations of prednisolone are biologically relevant, it was necessary to determine the free fraction in each plasma sample. Thirdly, due to the short half-life of prednisolone no steady-state is achieved, and therefore area under the concentration-time curve needed to be determined in all studies. Fourthly, prednisolone and prednisone are interconvertible and prednisolone is given intravenously as an ester prodrug, features which created controversies about the correct interpretation of pharmacokinetic results. Finally, the total body clearances of total and (to a lesser degree) of unbound prednisolone increase with increasing concentrations of prednisolone. Therefore, in order to compare pharmacokinetic results between different subjects, standardised doses had to be administered. The investigations performed so far have revealed that: (1) the dose-dependent pharmacokinetics partly explain the clinical observation that an alternate-day regimen with prednisone yields fewer biological effects; (2) the interconversion of prednisone into prednisolone is not a limiting factor, even in patients with severely impaired liver function; (3) hypoproteinaemia per se does not cause increased unbound concentrations of prednisolone in vivo; (4) patients with liver failure, renal failure or a renal transplant, subjects older than 65 years, women on estrogen-containing oral contraceptive steroids or subjects taking ketoconazole have increased unbound concentrations of prednisolone-whereas hyperthyroid patients, some patients with Crohn's disease, subjects taking microsomal liver enzyme-inducing agents or patients on intravenous prednisolone phthalate (instead of prednisolone phosphate) or on some brands of enteric coated prednisolone tablets have decreased concentrations of prednisolone. The biological relevance of the altered pharmacokinetics is supported in part by altered clinical effects and altered effects on cellular immunofunctions.

Prednisolone pharmacokinetics in cushingoid and non-cushingoid kidney transplant patients

Prednisolone pharmacokinetics and protein binding have been compared in 16 cushingoid and 46 non-cushingoid long-term kidney transplant recipients. After oral administration of 10 mg prednisolone, the cushingoid patients had a significantly higher peak prednisolone serum concentration (P less than 0.03), a longer elimination half-time (P less than 0.03), and a larger area under the time-concentration curve of total (P less than 0.01) and free (P less than 0.03) prednisolone. The apparent total body clearance of total and free prednisolone was significantly lower in the cushingoid than in the non-cushingoid patients (P less than 0.02 and less than 0.05, respectively). There was no significant difference in time of peak concentration, apparent volume of distribution or serum protein binding of prednisolone. It is suggested that the development and persistency of some cushingoid features may be related to a decreased total body clearance of prednisolone, which, in turn, may be influenced by impaired renal function.