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Background
Repository corticotropin injection (H.P. Acthar® Gel) (Questcor Pharmaceuticals, Union City, CA) is a natural product derived from a bovine or porcine source of the adrenocorticotropic hormone (ACTH), which stimulates the adrenal cortex to secrete cortisol, corticosterone, aldosterone, and a number of other androgenic substances. The release of ACTH is modulated by the nervous system via the corticotropin regulatory hormone released from the hypothalamus and by a negative corticosteroid feedback mechanism. Elevated plasma cortisol levels suppress ACTH release.
Repository corticotropin injection was originally approved by the U.S. Food and Drug Administration (FDA) in 1952 for a broad range of corticosteroid-responsive conditions including rheumatic, collagen, dermatologic, allergic states, ophthalmic, respiratory and edematous states. Current labeled indications include multiple sclerosis, rheumatic disorders, collagen diseases, dermatologic diseases, allergic states, ophthalmologic diseases, respiratory diseases, and edematous states. In addition, the FDA approved the use of repository corticotropin injection for treatment of infantile spasms in infants and children under 2 years of age.
There are a lack of clinical studies comparing the effectiveness of ACTH gel to corticosteroids in corticosteroid-responsive conditions. In addition, there is no reliable evidence of the effectiveness of ACTH gel in persons who have failed to respond to corticosteroids. Also, because of uncertainties in the effect of ACTH gel on the magnitude of endogenous cortisol production, ACTH gel has the potential for inducing significant adverse effects.
Bomback, et al. (2011) reported on a retrospective case series of 21 patients with nephrotic syndrome treated with ACTH gel, including 11 patients with idiopathic membranous nephropathy, 4 patients with membranoproliferative glomerulonephritis, 1 patient with focal glomerulosclerosis, 1 patient with minimal change disease, 1 patient with IgA nephropathy, 1 patient with class V systemic lupus erythematosis glomerulonephritis, 1 patient with monoclonal diffuse proliferative glomerulonephritis, and 1 patient with unbiopsied nephrotic syndrome. Given the small number of patients and the observational nature of this study, no formal statistical analyses were performed. Four patients achieved complete remission, and 7 patients achieved partial remission. Five patients reported steroid-like adverse effects. The authors stated that results of the study should be interpreted cautiously due to its limitations, including its retrospective nature, lack of randomization, lack of comparison or control group, and short duration of follow-up. The authors stated that this retrospective data analysis suggests that further studies are warranted to evaluate ACTH gel in the treatment of nephrotic syndrome.
Bomback, et al. (2012) conducted an open-label prospective study of ACTH gel in resistant glomerular diseases. Fifteen subjects with resistant glomerular diseases were treated with ACTH gel, including 5 subjects with idiopathic membranous nephropathy, 2 subjects with minimal change disease, 3 subjects with focal segmental glomerulosclerosis, and 5 subjects with IGA nephropathy. Subjects were treated with ACTH gel for 24 weeks, dosed at 40 units twice weekly subcutaneously for 2 weeks, then 80 units twice weekly subcutaneously afterward. Given the small number of subjects and the pilot design of the study, no formal statistical analysis of results was performed. As a grouip, the 5 subjects with membranous nephropathy went from a pre-ACTH median proteinuria of 3.80 mg/g to a post-ACTH median proteinuria of 3.79 mg/g. Two of the 5 subjects with membranous nephropathy achieved partial remission over the 6-month course of ACTH therapy. As a group, the 5 subjects with minimal change disease or focal segmental glomerulosclerosis went from a pre-ACTH median proteinuria of 1.96 mg/g to a post-ACTH median proteinuria of 1.93 mg/g. One subject with minimal change disease and one subject with focal segmental glomerulosclerosis achieved partial remission of proteinuria during ACTH therapy. As a group, the 5 subjects with IgA nephropathy went from a pre-ACTH median proteinuria of 1.59 mg/g to a post-ACTH median proteinuria of 0.85 mg/g. Three subjects with IgA nephropathy showed significant reductions in proteinuria to remission levels during the treatment period. Three subjects discontinued therapy early due to adverse events. Two subjects with diet-controlled diabetes had worsened glycemic control prompting initiation of oral hypoglycemic therapy. One subject complained of weight gain, Cushingoid faces, increased blood pressure, and worsening kidney function; the subject had experienced similar side effects with prednisone in the past. The authors stated that the data from this study are limited by the small subject sample, the lack of control group, and the relatively short-term follow-up. The authors stated that these data support further investigations of ACTH for patients with resistant glomerular diseases.
Thompson, et al. (1989) reported on a randomized, double-blind, controlled clinical study comparing the efficacy of intravenous methylprednisolone to intramuscular ACTH gel in the treatment of acute relapse in 61 patients with multiple sclerosis. Subjects randomized to methylprednisolone received 1 gram IV methylprednisolone daily for three days and 14 days of intramuscular placebo, and subjects randomized to ACTH gel received IV placebo daily for three days and at the same time a reducing course of intramuscular ACTH over 14 days, consisting of 80 units for 7 days, 40 units for 4 days, and 20 units for 3 days. Of the 61 subjects, 5 failed to complete the study, 2 on ACTH and 3 on methylprednisolone. The authors reported that there was a marked improvement in both groups over the course of the study, but no differences between groups in either the rate of recovery or final outcome in acute relapse. The authors noted that side effects in the methylprednisolone group were less frequent than in the ACTH group. The authors stated that giving a 3-day course of intravenous treatment rather than 14 days of intramuscular injections "has obvious advantages in terms of both patient comfort and medical resources."
Levine (2012) reported on a retrospective review of three patients with dermatomyositis and two patients with polymyositis who were treated with adrenocorticotropic hormone (ACTH) gel and who experienced a disease exacerbation and either failed or were unable to tolerate the side effects of previous therapy with steroids, intravenous immunoglobulins, and steroid-sparing drugs. Patients received ACTH gel subcutaneous injections of 80 U (1 mL) twice weekly (four patients) or once weekly (one patient) over the course of 12 weeks for short-term treatment of symptom exacerbations. Manual muscle testing using the Medical Research Council scale was assessed at baseline and at 3 months. The investigator reported that improvement was seen in all patients, including improved muscle strength, decreased pain, and resolution of skin involvement. The investigator stated that all patients tolerated the treatment well, and no significant side effects occurred. The author concluded that these anecdotal reports would suggest consideration of ACTH gel
as a therapeutic option, and that further investigation is warranted.
Thorpe (1969) reported on the use of adrenocorticotropic hormone in six patients with temporal arteritis/polymyalgia rheumatica syndrome. Patients were treated over a period of two to six months. Although no standardized objective clinical outcome measures were reported, the author reported that "all patients responded well to the regimen" and that two of the six patients remained on steroid therapy. The author stated that three patients had fluid retention requiring diuretic therapy, two patients had dyspepsia. One patient developed a febrile urinary tract infection and died. The author stated that a long-term study is warranted.
West syndrome (also known as infantile spasms) is a rare disorder that includes a peculiar type of epileptic seizure and an electroencephalogram (EEG) finding called "hypsarrhythmia". Onset usually occurs within the first year of life and peaks at 3 to 5 months. It is sometimes associated with cerebral palsy or Down's syndrome but little is known about the exact pathophysiology of the condition. While the seizures generally resolve by the age of three years, the long-term prognosis is poor. Psychomotor delay is severe in approximately 70 % of the cases and many will develop other forms of severe epilepsy. Few studies have evaluated the long-term outcome of West syndrome, but it is generally agreed that earlier control might improve prognosis (Hancock and Osborne, 2002).
Individuals diagnosed with infantile spasm are typically treated with a variety of agents; however, treatment has proven to be problematic since it is generally refractory to conventional anti-epileptic drugs. Repository corticotropin injection has FDA approval for treating patients with infantile spasms. While there is some evidence that supports the effectiveness of ACTH for the short-term treatment of infantile spasms and in resolution of hypsarrhythmia, the optimum treatment for infantile spasms has yet to be established.
The U.S. Food and Drug Administration (FDA) has approved H.P. Acthar Gel for treatment of infantile spasms (FDA, 2010). An FDA committee (2010) concluded that there was substantial evidence of effectiveness for Acthar Gel as a treatment for infantile spasms. This conclusion was based upon evidence from one randomized controlled clinical trial with confirmatory evidence. The committee agreed that effectiveness has been shown in the cessation of spasms and amelioration of the EEG, but not in the prevention of other seizure types, improvement in long-term developmental outcomes, or any other outcomes. According to the product labeling, the recommended regimen is a daily dose of 150 U/m2 (divided into twice-daily intra-muscular injections of 75 U/m2) administered over a 2-week period. Dosing with H.P. Acthar Gel should then be gradually tapered over a 2-week period to avoid adrenal insufficiency.
In a retrospective, multi-center study, researchers from Japan reviewed the medical records of 138 patients with West syndrome who were treated with low dose synthetic ACTH. The authors noted that at the end of ACTH therapy, excellent effect on seizures was noted in 106 (76 %) patients, good effect in 23 (17 %), and poor effect in 9 (7 %). Initial effects on EEG were excellent in 53 (38 %) patients, good in 76 (55 %), and poor in 9 (7 %). As for seizure prognosis at the time of follow-up, 51 of 99 (52 %) patients were seizure-free, whereas 48 (48 %) patients had seizures. Mental outcome was normal in 6 of 98 (6 %) patients, mild mental retardation in 16 (16 %), moderate mental retardation in 26 (27 %), and severe mental retardation in 50 (51 %). The initial effects of ACTH on seizures and long-term outcome were not dose dependent (daily dosage 0.005 to 0.032 mg/kg, 0.2 to 1.28 IU/kg; total dosage 0.1 to 0.87 mg/kg, 4 to 34.8 IU/kg). The severity of adverse effects correlated with total dosage of ACTH, and the severity of brain volume loss due to ACTH correlated well with the daily dosage and total dosage of ACTH. The authors concluded that low-dose synthetic ACTH therapy is as effective for the treatment of West syndrome as higher doses (Ito et al, 2002).
A Cochrane review on the treatment of infantile spasms (2002) compared the effects of single drugs used to treat infantile spasms in terms of long-term psychomotor development, subsequent epilepsy, control of the spasms and adverse effects. Fourteen randomized controlled trials with a total of 667 participants were included in the review and 9 different drugs were evaluated (vigabatrin, ACTH (seven different treatment regimes and different preparations), prednisone, hydrocortisone, nitrazepam, sodium valproate, sulthiame, methysergide and alpha-methylparatyrosine). The review reported that overall, the methodology of the studies was poor due to ethical dilemmas such as giving placebo injections to children. Findings from 2 small studies showed ACTH to be more efficacious than low-dose prednisone (2 mg/kg). One study suggested that hormonal treatments (prednisolone or tetracosactide) might improve long-term developmental outcome compared with vigabatrin in patients who are not found to have an underlying cause for their infantile spasms. One small study found vigabatrin to be more efficacious than hydrocortisone in stopping infantile spasms due to tuberous sclerosis. Few studies considered psychomotor development or subsequent seizure rates as outcomes and none had long-term follow-up; few side effects or deaths were reported. A clear statement on the optimum treatment for infantile spasms could not be made, however, the reviewers stated that (i) hormonal treatment (i.e., ACTH, tetracosactide or high dose prednisolone) will resolve spasms faster than vigabatrin in more infants (but this may or may not translate into better long term outcome), (ii) if prednisone or vigabatrin are used, then high dosage is recommended, (iii) vigabatrin may be the treatment of choice in tuberous sclerosis but more research is required, and (iv) resolution of the EEG may be important but this has not been proven. The authors concluded that further trials with larger numbers of participants and longer follow-up are needed.
This is consistent with Riikonen's review (2005) on best treatment practices of infantile spasms in Finland. Riikonen stated that hormonal treatment is the most effective therapy in the short-term treatment of infantile spasms. One study found large doses of prednisolone to be as effective as corticotrophin. Vigabatrin is the treatment of choice for infants with tuberous sclerosis. An earlier review by Riikonen (2004) reported that in an open, randomized, prospective study, the efficacy and relapse rates of ACTH and vigabatrin treatment did not differ significantly and that the high response rates in tuberous sclerosis complex were similar. Both drugs had severe side effects. In the long-term follow-up of 20 to 35 years, 1/3 of the patients died, the intellectual outcome of the remaining patients was normal or slightly subnormal, and 1/4 to 1/3 of the patients were seizure-free. Riikonen stated that ACTH should be the first choice for treatment of infantile spasms since the side effects of ACTH, unlike those of vigabatrin, are well- known, treatable, and reversible; however, the author concluded that an open, prospective study to compare the efficacy, relapse rate, and long-term outcome of treatment with ACTH and vigabatrin is urgently needed.
The American Academy of Neurology and Child Neurology Society (Mackay et al, 2004) reviewed 159 articles to determine the current practice parameter on the medical treatment of infantile spasms. Outcome measures included complete cessation of spasms, resolution of hypsarrhythmia, relapse rate, developmental outcome, and presence or absence of epilepsy or an epileptiform EEG. The practice parameter concluded that (i) ACTH is probably an effective agent in the short-term treatment of infantile spasms, but there is insufficient evidence to recommend the optimum dosage and duration of treatment, (ii) vigabatrin is possibly effective for the short-term treatment of infantile spasm and is possibly also effective for children with tuberous sclerosis, (iii) there is insufficient evidence to recommend oral corticosteroids, (iv) there is insufficient evidence to recommend any other treatment of infantile spasms, and (v) there is insufficient evidence to conclude that successful treatment of infantile spasms improves the long-term prognosis.
Kivity et al (2004) evaluated the long-term cognitive and seizure outcomes of patients (n = 37) with cryptogenic infantile spasms treated within 1 month of onset with high-dose synthetic ACTH. The patients received a standardized treatment regimen of high-dose tetracosactide depot, 1 mg IM every 48 h for 2 weeks, with a subsequent 8- to 10-week slow taper and followed by oral prednisone, 10 mg/day for a month, with a subsequent slow taper for 5 months or until the infant reached the age of 1 year, whichever came later. Seizure outcomes were followed up prospectively. Cognitive outcomes were determined after 6 to 21 years and analyzed in relation to treatment lag and pre-treatment regression. Twenty-two infants were treated within 1 month of onset of infantile spasms, and 15 after 1 to 6.5 months. Normal cognitive outcome was found in all 22 (100 %) patients of the early-treatment group, and in 40 % of the late-treatment group. Normal cognitive outcome was found in all 25 (100 %) patients who had no or only mild mental deterioration at presentation, including 4 in the late-treatment group but in only 3 of the 12 patients who had had marked or severe deterioration before treatment. The authors reported that while early treatment of cryptogenic infantile spasms with a high-dose ACTH protocol is associated with favorable long-term cognitive outcomes, further studies are needed on the optimal treatment regimen for this disorder.
The United Kingdom Infantile Spasms Study (UKISS), a multi-center randomized trial, compared hormonal treatment with vigabatrin on developmental and epilepsy outcome to age 14 months. Infants were randomly assigned hormonal treatment (n = 55) or vigabatrin (n = 52) and were followed-up until clinical assessment at 12 to 14 months of age. Neurodevelopment was assessed with the Vineland adaptive behavior scales (VABS) at 14 months of age on an intention-to-treat basis. Of 107 infants enrolled, 5 died and 101 survivors reached both follow-up assessments. Absence of spasms at final clinical assessment was similar in each treatment group and mean VABS score did not differ significantly. In infants with no identified underlying etiology, the mean VABS score was higher in those allocated hormonal treatment than in those allocated vigabatrin. Results indicated that hormonal treatment controls spasms better than does vigabatrin initially, but not at 12 to 14 months of age. The authors concluded that better initial control of spasms by hormonal treatment in those with no identified underlying etiology may lead to improved developmental outcome (Lux et al, 2005).
The consensus opinion from 39 U.S. physicians specializing in pediatric epilepsy reported that as initial therapy for infantile spasms caused by tuberous sclerosis, vigabatrin and ACTH were considered first line treatments; however, vigabatrin was considered the treatment of choice. As initial therapy for infantile spasms that are symptomatic in etiology, ACTH and topiramate were considered first line treatments, however, ACTH was considered the treatment of choice (Wheless et al, 2005). The consensus opinion from 42 European physicians specializing in pediatric epilepsy reported that as initial therapy for infantile spasms caused by tuberous sclerosis, viagabatrin was considered the treatment of choice. As initial therapy for infantile spasms that are symptomatic in etiology, vigabatrin was also considered the treatment of choice, with ACTH and prednisone other first-line options (Wheless et al, 2007).
Repository corticotropin should be used in the lowest dose for the shortest period of time to accomplish the therapeutic goal. Adverse effects with ACTH are potentially life threatening problems that include depression of the immune system and modified response to infection leading to overwhelming sepsis. Minor side effects include behavioral changes especially irritability, changes in appetite, weight gain and alteration in sleep patterns.
Adrenocorticotropic hormone is a natural product derived from a bovine or porcine source and is administered as an intramuscular or subcutaneous injection. However, in the United Kingdom, with the existing concerns surrounding bovine spongiform encephalopathy, ACTH has been withdrawn from the market. Tetracosactide is a synthetic alternative to ACTH and displays the same physiological properties as ACTH. In Europe and Japan synthetic ACTH is usually available, while in the United States natural ACTH derivatives are normally used. Vigabatrin, another medication used for infantile spasms, is not licensed for use in the United States.
Repository corticotropin is contraindicated in patients with scleroderma, osteoporosis, systemic funcal infections, ocular herpes simplex, recent surgery, history of or the presence of a peptic ulcer, congestive heart failure, hypertension, or sensitivity to proteins of porcine origin.
Appendix
Recommended Dosing Regimen for Acute Exacerbations of Multiple Sclerosis
The recommended dose is daily intramuscular or subcutaneous doses of 80-120 units for 2-3 weeks for acute exacerbations. Dosage should be individualized according to the medical condition of each patient. Frequency and dose of the drug should be determined by considering the severity of the disease and the initial response of the patient.
Although drug dependence does not occur, sudden withdrawal of H.P. Acthar Gel after prolonged use may lead to adrenal insufficiency or recurrent symptoms which make it difficult to stop the treatment. It may be necessary to taper the dose and increase the injection interval to gradually discontinue the medication.
Recommended Dosing Regimen for Other Indications for Adults and Children Over Two Years of Age
Dosage should be individualized according to the disease under treatment and the general medical condition of each patient. Frequency and dose of the drug should be determined by considering severity of the disease and the initial response of the patient. The usual dose of H.P. Acthar Gel is 40-80 units given intramuscularly or subcutaneously every 24-72 hours.
Although drug dependence does not occur, sudden withdrawal of H.P. Acthar Gel after prolonged use may lead to adrenal insufficiency or recurrent symptoms which make it difficult to stop the treatment. It may be necessary to taper the dose and increase the injection interval to gradually discontinue the medication.
Source: Questcor Pharmaceuticals, Inc. H.P. Acthar Gel (repository corticotropin injection) Injection, Gel for Intramuscular | Subcutaneous Use. Initial U.S. Approval: 1952. Prescribing Information. PL065/Rev.03 No. 1350. PM-554-01. Hayward, CA: Questcor; issued June 2011.
Recommended Dosage Regimen for Infantile Spasms in Infants and Children Under 2 Years of Age
H.P. Acthar Gel is typically dosed based on body surface area (BSA) for infantile spasms. To calculate body surface area (BSA), see http://www-users.med.cornell.edu/~spon/picu/calc/bsacalc.htm.
In the treatment of infantile spasms, H.P. Acthar Gel must be administered intramuscularly. The recommended regimen is a daily dose of 150 U/m2 (divided into twice daily intramuscular injections of 75 U/m2) administered over a 2-week period. Dosing with H.P. Acthar Gel should then be gradually tapered over a 2-week period to avoid adrenal insufficiency. The following is one suggested tapering schedule: 30 U/m2 in the morning for 3 days; 15 U/m2 in the morning for three days; 10 U/m2 in the mornining for three days; and 10 U/m2 every other morning for six days.
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