Drug Selection and Posology, Optimal Therapies and Risk/Benefit Assessment in Medicine: The Paradigm of Iron-Chelating Drugs.

The design of clinical protocols and the selection of drugs with appropriate posology are critical parameters for therapeutic outcomes. Optimal therapeutic protocols could ideally be designed in all diseases including for millions of patients affected by excess iron deposition (EID) toxicity based on personalised medicine parameters, as well as many variations and limitations. EID is an adverse prognostic factor for all diseases and especially for millions of chronically red-blood-cell-transfused patients. Differences in iron chelation therapy posology cause disappointing results in neurodegenerative diseases at low doses, but lifesaving outcomes in thalassemia major (TM) when using higher doses. In particular, the transformation of TM from a fatal to a chronic disease has been achieved using effective doses of oral deferiprone (L1), which improved compliance and cleared excess toxic iron from the heart associated with increased mortality in TM. Furthermore, effective L1 and L1/deferoxamine combination posology resulted in the complete elimination of EID and the maintenance of normal iron store levels in TM. The selection of effective chelation protocols has been monitored by MRI T2* diagnosis for EID levels in different organs. Millions of other iron-loaded patients with sickle cell anemia, myelodysplasia and haemopoietic stem cell transplantation, or non-iron-loaded categories with EID in different organs could also benefit from such chelation therapy advances. Drawbacks of chelation therapy include drug toxicity in some patients and also the wide use of suboptimal chelation protocols, resulting in ineffective therapies. Drug metabolic effects, and interactions with other metals, drugs and dietary molecules also affected iron chelation therapy. Drug selection and the identification of effective or optimal dose protocols are essential for positive therapeutic outcomes in the use of chelating drugs in TM and other iron-loaded and non-iron-loaded conditions, as well as general iron toxicity.

Dose Assessment Following a 238Pu-contaminated Wound Case with Chelation and Excision.

The urinary excretion and wound retention data collected after a Pu-contaminated wound were analyzed using Markov Chain Monte Carlo (MCMC) to obtain the posterior distribution of the intakes and doses. An empirical approach was used to model the effects of medical treatments (chelation and excision) on the reduction of doses. It was calculated that DTPA enhanced the urinary excretion, on average, by a factor of 17. The empirical analysis also allowed calculation of the efficacies of the medical treatments-excision and chelation averted approximately 76% and 5.5%, respectively, of the doses that would have been if there were no medical treatment. All bioassay data are provided in the appendix for independent analysis and to facilitate the compartmental modeling approaches being developed by the health physics community.

Development of a New Chelation Model: Bioassay Data Interpretation and Dose Assessment after Plutonium Intake via Wound and Treatment with DTPA.

The administration of chelation therapy to treat significant intakes of actinides, such as plutonium, affects the actinide's normal biokinetics. In particular, it enhances the actinide's rate of excretion, such that the standard biokinetic models cannot be applied directly to the chelation-affected bioassay data in order to estimate the intake and assess the radiation dose. The present study proposes a new chelation model that can be applied to the chelation-affected bioassay data after plutonium intake via wound and treatment with DTPA. In the proposed model, chelation is assumed to occur in the blood, liver, and parts of the skeleton. Ten datasets, consisting of measurements of C-DTPA, Pu, and Pu involving humans given radiolabeled DTPA and humans occupationally exposed to plutonium via wound and treated with chelation therapy, were used for model development. The combined dataset consisted of daily and cumulative excretion (urine and feces), wound counts, measurements of excised tissue, blood, and post-mortem tissue analyses of liver and skeleton. The combined data were simultaneously fit using the chelation model linked with a plutonium systemic model, which was linked to an ad hoc wound model. The proposed chelation model was used for dose assessment of the wound cases used in this study.

Chelation Modeling: The Use of Ad Hoc Models and Approaches to Overcome a Dose Assessment Challenge.

Chelating agents are administered to treat significant intakes of radioactive elements such as plutonium, americium, and curium. These drugs may be used as a medical countermeasure after radiological accidents and terrorist acts. The administration of a chelating agent, such as Ca-DTPA or Zn-DTPA, affects the actinide's normal biokinetics. It enhances the actinide's rate of excretion, posing a dose assessment challenge. Thus, the standard biokinetic models cannot be directly applied to the chelation-affected bioassay data in order to assess the radiation dose. The present study reviews the scientific literature, from the early 1970s until the present, on the different studies that focused on developing new chelation models and/or modeling of bioassay data affected by chelation treatment. Although scientific progress has been achieved, there is currently no consensus chelation model available, even after almost 50 y of research. This review acknowledges the efforts made by different research groups, highlighting the different methodology used in some of these studies. Finally, this study puts into perspective where we were, where we are, and where we are heading in regards to chelation modeling.

Adherence to iron chelation therapy in patients who switched from deferasirox dispersible tablets to deferasirox film-coated tablets.

OBJECTIVE: To compare real-world adherence to and persistence with deferasirox film-coated tablets (DFX-FCT) and deferasirox dispersible tablets (DFX-DT) among patients who switched from DFX-DT to DFX-FCT, overall and by disease type (sickle cell disease [SCD], thalassemia, and myelodysplastic syndrome [MDS]). METHODS: Patients were ≥2 years old and had ≥2 DFX-FCT claims over the study period and ≥2 DFX-DT claims before the index date (first DFX-FCT claim). The DFX-DT period was defined from the first DFX-DT claim to the index date; the DFX-FCT period was defined from the index date to the end of the study period. Adherence was measured as medication possession ratio (MPR) and proportion of days covered (PDC). Persistence was defined as continuous medication use without a gap ≥30 or 60 days between refills. Comparisons were conducted using paired-sample Wilcoxon sign-rank and McNemar's tests. RESULTS: In total, 606 patients were selected (SCD: 348; thalassemia: 107; MDS: 106; other: 45). Adherence and persistence in the DFX-FCT vs DFX-DT period was significantly higher across all measures: mean MPR was 0.80 vs 0.76 (p < .001); 60.9% vs 54.3% of patients had MPR ≥ 0.8 (p = .009); mean 3-month PDC was 0.83 vs 0.71 (p < .001); 64.2% vs 45.4% of patients had 3-month PDC ≥ 0.8 (p < .001); 87.2% vs 63.4% of patients had 3-month persistence with no gap ≥30 days and 96.1% vs 79.9% with no gap ≥60 days (p < .001). Adherence and persistence improved after switching across all diseases, particularly MDS. CONCLUSIONS: Adherence and persistence improved significantly after switching from DFX-DT to DFX-FCT for all diseases, but especially MDS.

Chelation therapy and cardiovascular disease: connecting scientific silos to benefit cardiac patients.

Medical practitioners have treated atherosclerotic disease with chelation therapy for over 50 years. Lack of strong of evidence led conventional practitioners to abandon its use in the 1960s and 1970s. This relegated chelation therapy to complementary and alternative medicine practitioners, who reported good anecdotal results. Concurrently, the epidemiologic evidence linking xenobiotic metals with cardiovascular disease and mortality gradually accumulated, suggesting a plausible role for chelation therapy. On the basis of the continued use of chelation therapy without an evidence base, the National Institutes of Health released a Request for Applications for a definitive trial of chelation therapy. The Trial to Assess Chelation Therapy (TACT) was formulated as a 2 × 2 factorial randomized controlled trial of intravenous EDTA-based chelation vs. placebo and high-dose oral multivitamins and multiminerals vs. oral placebo. The composite primary endpoint was death, reinfarction, stroke, coronary revascularization, or hospitalization for angina. A total of 1708 post-MI patients who were 50 years or older with a creatinine of 2.0 or less were enrolled and received 55,222 infusions of disodium EDTA or placebo with a median follow-up of 55 months. Patients were on evidence-based post-MI medications including statins. EDTA proved to be safe. EDTA chelation therapy reduced cardiovascular events by 18%, with a 5-year number needed to treat (NNT) of 18. Prespecified subgroup analysis revealed a robust benefit in patients with diabetes mellitus with a 41% reduction in the primary endpoint (5-year NNT = 6.5), and a 43% 5-year relative risk reduction in all-cause mortality (5-year NNT = 12). The magnitude of benefit is such that it suggests urgency in replication and implementation, which could, due to the excellent safety record, occur simultaneously.

An assessment of iron overload in children treated for cancer and nonmalignant hematologic disorders.

UNLABELLED: Our goal was to assess the natural fate of iron overload (IO) following transfusions of packed red blood cells (PRBCs) in children treated for cancer and nonmalignant disorders according to the intensity level of their treatment. Sixty-six children were followed up from February 2010 to March 2013. The transfusion burden was compared between three treatment intensity groups assigned according to the Intensity of Treatment Rating Scale 3.0 (ITR-3). IO was assessed by serial measurements of serum ferritin (SF) (n= 66) and quantification of tissue iron by magnetic resonance imaging (MRI) (n=12). Of the children studied, 36 % (24/66) received moderately intensive treatment (level 2), 21 % (14/ 66) received very intensive treatment (level 3), and 42 % (28/ 66) received the most intensive treatment (level 4). The number of PRBC (p=0.016), the total transfused volume (p= 0.026), and transfused volume adjusted to body weight (p= 0.004) were significantly higher in the level 4 group. By the median follow-up time of 35.5 months (range 8­133), 21­ 29 % of patients (including level 2 and level 3 children) had SF >1,000 µg/l 1 year after cessation of transfusions. The slowest decrease of SF was observed in the level 4 group. Initial MRI examination demonstrated either mild or moderate IO in the liver and spleen. Repetitive MRI showed significant improvement in relaxation time between the initial and follow-up MRI performances in the liver (5.9 vs. 8.6 ms, p= 0.03) and the spleen (4.3 vs. 8.8 ms, p=0.03). CONCLUSION: IO diminished over time, but in the level 4 patients, it was detectable for years after cessation of transfusions.

Implications of the new lead screening recommendations in North Carolina.

In June of 2012, the Centers for Disease Control and Prevention updated their recommendations regarding the prevention of childhood lead poisoning. This commentary provides an overview of the new recommendations for blood lead screening and follow up.

EDTA chelation reappraisal following new clinical trials and regular use in millions of patients: review of preliminary findings and risk/benefit assessment.

EDTA chelation therapy is regularly used in thousands of patients worldwide. An FDA approval of more than 50 years ago for heavy metal detoxification prompted many physicians to use EDTA as an alternative medicine for many categories of patients. Recently, NIH initiated the so-called Trial to Assess Chelation Therapy (TACT), which has been designed to evaluate whether EDTA and high dose oral vitamins and mineral therapy could offer clinical, quality of life, and economic benefits for patients with a previous myocardial infraction. A 50% reduction of urinary Pb and improvement of systolic blood pressure was observed in 33 cardiovascular patients following 20 iv administrations. In another study involving 15 patients of different categories, EDTA also has been shown to be an effective and nontoxic chelator for the removal of xenobiotic metals such as Pb, Cd, Ni and Al. Administration of iv EDTA on weekly basis appears to be a sufficient and nontoxic protocol for treating patients with suspected overload and toxicity of xenobiotic metals especially Pb and Cd. The causative effect of xenobiotic metals in cancer, cardiovascular, neurodegenerative, renal and other diseases needs further investigation. Similarly, the use of EDTA chelation therapy in other conditions, which are not related to xenobiotic metal toxicity needs further investigation and confirmation of therapeutic use from controlled randomized clinical trials. Metal balance and drug interaction studies are required to clarify the risk/benefit assessment for the long term use of EDTA in patients with excess xenobiotic metal toxicity and in other conditions.

A new tool for the assessment of satisfaction with iron chelation therapy (ICT-Sat) for patients with ß-thalassemia major.

BACKGROUND: High satisfaction with iron chelation is a major determinant for adherence to ICT in beta-thalassaemia major (ß-TM) patients. In this study, a new tool to assess different domains of satisfaction for available forms of ICT was developed and validated. The impact of patients' satisfaction with ICT has been tested. METHODS: Items were generated via focus groups and a preliminary version with 24 items (ICT-Sat) with an additional item for treatment preference and a knowledge questionnaire (KQ) was developed. 170 ß-TM patients from three Thalassaemia centers in Egypt, aged 2-32 years received three questionnaires to fill in; the new ICT-Sat, a KQ, and a previously validated tool for satisfaction with ICT (SICT) and retested 4-6 weeks later to ensure re-test reliability. Type of chelation, drug related adverse events, compliance with ICT, and serum ferritin level (SF) during the year prior to the study as well as available cardiac T2*data were recorded. RESULTS: One hundred and fifty two ß-TM patients completed all questionnaires; median age was 12 years. The final 15 remaining ICT-Sat items, yielding to four domain scores, explained 70.6% of the total variance. The "perceived effectiveness" and "fear and worries" domains of the ICT-Sat correlated significantly with the domains "perceived effectiveness" and "acceptance" of the SICT. Patients treated with oral ICT were more satisfied with perceived effectiveness, and their side effects. CONCLUSIONS: A new clinically based ICT-Sat tool was developed and revealed good psychometric characteristics. Adherence to ICT was better correlated with "perceived effectiveness" and SF level.

Iron overload in thalassemia and related conditions: therapeutic goals and assessment of response to chelation therapies.

Transfusional iron loading inevitably results in hepatic iron accumulation, with variable extrahepatic distribution that is typically less pronounced in sickle cell disease than in thalassemia disorders. Iron chelation therapy has the goal of preventing iron-mediated tissue damage through controlling tissue iron levels, without incurring chelator-mediated toxicity. Historically, target levels for tissue iron control have been limited by the increased frequency of deferoxamine-mediated toxicity and low levels of iron loading. With newer chelation regimes, these limitations are less evident. The reporting of responses to chelation therapies has typically focused on average changes in serum ferritin in patient populations. This approach has three limitations. First, changes in serum ferritin may not reflect trends in iron balance equally in all patients or for all chelation regimens. Second, this provides no information about the proportion of patients likely respond. Third, this gives insufficient information about iron trends in tissues such as the heart. Monitoring of iron overload has advanced with the increasing use of MRI techniques to estimate iron balance (changes in liver iron concentration) and extrahepatic iron distribution (myocardial T2*). The term nonresponder has been increasingly used to describe individuals who fail to show a downward trend in one or more of these variables. Lack of a response of an individual may result from inadequate dosing, high transfusion requirement, poor treatment adherence, or unfavorable pharmacology of the chelation regime. This article scrutinizes evidence for response rates to deferoxamine, deferiprone (and combinations), and deferasirox.

Assessment of survival in a 2-year comparative study of lanthanum carbonate versus standard therapy.

OBJECTIVE: Epidemiological data link elevated levels of serum phosphorus with increased mortality among patients with chronic kidney disease. Recent data also suggest improved survival with the use of dietary phosphate binders in patients on dialysis. However, few studies have comprehensively evaluated the survival benefit associated with different phosphate binders. A post-hoc survival analysis was undertaken of lanthanum carbonate (Fosrenol *) versus standard therapy. RESEARCH DESIGN AND METHODS: Patients on dialysis enrolled in a phase 3, 2-year, comparative safety study were randomized 1:1 to lanthanum carbonate or standard therapy to treat serum phosphorus to a target of < or =5.9 mg/dL (1.90 mmol/L). Patients (N = 1354) were followed up for survival status during, or after completion of or discontinuation from the study. MAIN OUTCOME MEASURES: Survival was measured by time from first dose of study medication to all-cause mortality or last contact. RESULTS: The distribution of follow-up time was similar in the lanthanum carbonate and standard therapy groups (mean 23.7 versus 23.9 months [median 27.0 versus 26.0 months], respectively). Serum phosphorus levels were similar across treatment groups, as patients were treated to target. At follow-up, 19.9% (135/680) of patients treated with lanthanum carbonate had died versus 23.3% (157/674) on standard therapy (log-rank p = 0.18). In the subgroup of patients aged >65 years (n = 336), 27.0% (44/163) of lanthanum-carbonate-treated patients had died compared with 39.3% (68/173) on standard therapy (log-rank p = 0.04). CONCLUSION: In these survival analyses, overall mortality was similar in the lanthanum carbonate and standard therapy groups, but results suggest that there was a survival benefit associated with lanthanum carbonate treatment for patients aged >65 years, who are likely to carry the greatest burden of vascular calcification. These results were similar to those observed in the Dialysis Clinical Outcomes Revisited study, a prospective trial of sevelamer hydrochloride designed to assess survival.

[Phosphorus (P) chelant in dialysis: efficacy and cost. Peritoneal dialysis solutions]. / Quelantes de fósforo (P) en diálisis: eficacia y coste. Soluciones de diálisis peritoneal.

Sevelamer use has a high prevalence, and half of patients are treated with this noncalcium binder. Two randomized studies appeared in 2007 that compared the efficacy of sevelamer over calcium salts. In the more statistically potent of the two studies, no differences were found in mortality between the sevelamer and calcium groups, except for a benefit in favor of sevelamer in patients older than 65 years. In the other less statistically potent study, lower mortality was observed in the sevelamer group. Both studies have various deficiencies and a timely meta-analysis of the two studies appearing that same year concluded that there was no significant evidence demonstrating a superior efficacy of sevelamer over calcium salts. Therefore, generalized extension of its use as a first-line binder is not recommended. However, its use can be assessed in specific clinical situations. With regard to the cost-benefit ratio, as there is no evidence that greater clinical benefits are obtained with sevelamer than with calcium salts, prudence and moderation in its use are needed because of the high cost/benefit ratio demonstrated. Otherwise, we will contribute to increasing the already very high treatment cost in these patients, with one of the highest costs per life year gained in medicine. The cost/benefit ratio of sevelamer remains unattractive from an economic point of view, even if dialysis and transplant are excluded in these patients.

Withdrawal of penicillamine from zinc sulphate-penicillamine maintenance therapy in Wilson's disease: promising, safe and cheap.

BACKGROUND: Penicillamine, once considered the cornerstone of treatment for Wilson disease (WD), is rather expensive and toxic, and often causes neurological worsening. Zinc sulphate, aiming at the treatment of free-copper toxicosis, has emerged as effective, safe and cheap alternative. AIM: To assess the effect of withdrawal of penicillamine from maintenance treatment with penicillamine and zinc sulphate. PATIENTS AND METHODS: 45 patients of WD (M:F: 28:17; age at diagnosis: 13.5+/-63 years), on both penicillamine (P) and zinc sulphate (Zn), couldn't continue penicillamine due to financial constraints. Their clinical data, disability and impairment scores (Schwab and England (S&E) score, Neurological Symptom Score (NSS), and Chu staging) and follow-up data of patients maintained only on zinc sulphate were recorded. RESULTS: Majority of patients (84.4%) had neuropsychiatric manifestations. The mean duration of treatment with penicillamine (P) and zinc sulphate (P+Zn), before stopping penicillamine, was 107.4+/-67.3 months. 40 patients improved variably, while the rest didn't. They received only zinc sulphate for 27.2+/-8.5 months (range: 12 to 34) and 44 patients (97.7%) remained status quo or improved marginally. Only one patient reported worsening in dysarthria. Their disability and impairment scores during combination (penicillamine and zinc sulphate) and Zn alone were: Chu (1.3+/-0.5 vs. 1.5+/-1.9; p=0.4), NSS (1.8+/-3.1 vs. 1.5+/-2.3; p=0.03) and S&E (96.4+/-5.6 vs. 98.6+/-3.5; p=0.03). There were no adverse effects. CONCLUSIONS: Withdrawal of penicillamine from zinc sulphate/penicillamine maintenance therapy for patients with Wilson's disease was effective, safe and economic, for almost all patients. This retrospective study reiterates that zinc sulphate may be used as a preferred mode of treatment for patients with Wilson's disease.

Thalassemia intermedia today: should patients regularly receive transfusions?

BACKGROUND: beta-Thalassemia is an inherited hemoglobin disorder characterized by reduced synthesis of beta-globin chain. The severity of clinical course distinguishes this heterogeneous disease in two main subtypes: thalassemia major (TM) and thalassemia intermedia (TI). TI has a later clinical onset with a milder anemia that does not require transfusions at least during the first few years of life. The clinical picture of TI patients who have not received transfusions or have occasionally received transfusions is dominated by the consequences of chronic hemolytic anemia, tissue hypoxia, and their compensatory reactions, such as bone deformities and fractures, extramedullary hemopoiesis, spleen and liver enlargement, hypercoagulability, and pulmonary hypertension. These complications, especially the latter two, are getting more frequent and severe over the years. Nowadays, although TI patients have almost no changes in the course of the disease, well-treated TM patients with regular transfusion-chelation therapy showed suppression of the anemia-related disorders in parallel to prolongation of life. The new oral iron chelators and the magnetic resonance imaging application for early detection of heart iron load are promising for further improvement on survival. CONCLUSIONS: Considering the current cost-benefit balance of regular treatment in TM as well as the frequency and severity of complications in TI, it seems that the majority of TI patients will be benefited if this kind of treatment is applied targeting prevention and not palliation of the anemia-induced complications.

Management of elevated blood lead in Tennessee's children: questions a physician might ask.

OBJECTIVES: To present the most commonly asked questions health care providers have about the management of a child with elevated blood lead, and the answers based on current guidelines. METHODS: Questions answered in this paper were selected based on recall of three years' experience as a statewide physician lead consultant in Alabama and Tennessee. RESULTS: 20 questions are presented, along with relevant Tennessee resources for obtaining more information and medical consultation. CONCLUSIONS: Tennessee's Childhood Lead Poisoning Prevention Program has the resources to assist health care providers with any child who presents with lead poisoning. No Tennessee health care provider should lack the knowledge to manage any lead poisoned child.