Dichlorphenamide: A Review in Primary Periodic Paralyses.

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Dichlorphenamide: A Review in Primary Periodic Paralyses. Greig SL; Drugs. 2016 Mar;76(4):501-7. doi: 10.1007/s40265-016-0559-2.

Abstract

Oral dichlorphenamide (Keveyis™) is a carbonic anhydrase inhibitor that is approved in the USA for the treatment of primary hyperkalaemic and hypokalaemic periodic paralyses and related variants. The efficacy and safety of dichlorphenamide in patients with primary periodic paralyses have been evaluated in four 9-week, randomized, double-blind, placebo-controlled, phase III trials [two parallel-group trials (HOP and HYP) and two crossover trials]. In two trials in patients with hypokalaemic periodic paralysis, dichlorphenamide was associated with a significantly (eightfold) lower paralytic attack rate and fewer patients with acute intolerable worsening compared with placebo. In two trials in patients with hyperkalaemic periodic paralysis, the attack rate was lower with dichlorphenamide than placebo, with this comparison reaching statistical significance in one trial (crossover) but not the other (HYP), although the attack rate was approximately fivefold lower with dichlorphenamide than placebo in the HYP trial. In 52-week, open-label extensions of the HOP and HYP trials, dichlorphenamide provided sustained efficacy in patients with hypokalaemic or hyperkalaemic periodic paralysis. Dichlorphenamide was generally well tolerated in all four phase III trials and during the extension trials; the most common adverse events were paraesthesia, cognitive disorders and dysgeusia. As the first agent to be approved in the USA for this indication, dichlorphenamide is a valuable treatment option for patients with primary hyperkalaemic or hypokalaemic periodic paralysis. PMID: 26941026 [PubMed - in process]

Identification of the KCNJ2 Mutation in a Korean Family with Andersen-Tawil Syndrome and Developmental Delay.  Kim NR, Jang JH, Jeon GW, Cho EH, Sin JB;  Ann Clin Lab Sci. 2016 Jan;46(1):110-3.

Andersen-Tawil syndrome is a rare autosomal dominant disease characterized by the clinical triad of periodic paralysis, long QT with ventricular arrhythmias, and dysmorphic facial or skeletal features. However, the phenotypic heterogeneity and poor disease awareness of this syndrome can hinder an accurate and timely diagnosis. In this study, we describe a Korean family with Andersen-Tawil syndrome with a G215D mutation of the KCNJ2 gene revealed by diagnostic exome sequencing. Two sisters had severe growth restriction, characteristic facial anomalies, and developmental delay. The father carried the same mutation with similar characteristic facial features and short stature. This family lacked periodic paralysis. This report highlights the importance of an exome study for unusual clinical manifestations, such as preand postnatal growth restriction, developmental delay, and the lack of a critical diagnostic clue, such as periodic paralysis. PMID: 26927354 [PubMed - in process]

Hypokalaemic Periodic Paralysis in a Patient with Subclinical Hyperthyroidism: A Rare Case. Hegde S, Shaikh MA, Gummadi T.;J Clin Diagn Res. 2016 Jan;10(1):OD14-5. doi: 10.7860/JCDR/2016/15489.7131.

Thyrotoxic Periodic Paralysis (TPP) is an uncommon disorder. Though many cases of hypokalaemic periodic paralysis are reported in overt hyperthyroidism, hypokalaemic paralysis in subclinical hyperthyroidism is very rare. Subclinical hyperthyroidism is characterised by circulating TSH levels below reference range and normal thyroid hormone levels. We describe a case of 32-year-old Asian male who presented to the emergency department with acute onset weakness and hypokalaemia with no previous history of thyroid disorder or any signs and symptoms suggestive of hyperthyroidism. He was subsequently diagnosed with Graves' disease with subclinical hyperthyroidism. PMID: 26894115 [PubMed] PMCID: PMC4740643


Randomized, placebo-controlled trials of dichlorphenamide in periodic paralysis.Neurology. 2016 Feb 10. pii: 10.1212/WNL.0000000000002416. Sansone VA, Burge J, McDermott MP, et. al. 

OBJECTIVE: To determine the short-term and long-term effects of dichlorphenamide (DCP) on attack frequency and quality of life in hyperkalemic (HYP) and hypokalemic (HOP) periodic paralysis.
METHODS: Two multicenter randomized, double-blind, placebo-controlled trials lasted 9 weeks (Class I evidence), followed by a 1-year extension phase in which all participants received DCP. Forty-four HOP and 21 HYP participants participated. The primary outcome variable was the average number of attacks per week over the final 8 weeks of the double-blind phase.
RESULTS: The median attack rate was lower in HOP participants on DCP than in participants on placebo (0.3 vs 2.4, p = 0.02). The 9-week mean change in the Physical Component Summary score of the Short Form-36 was also better in HOP participants receiving DCP (treatment effect = 7.29 points, 95% confidence interval 2.26 to 12.32, p = 0.006). The median attack rate was also lower in HYP participants on DCP (0.9 vs 4.8) than in participants on placebo, but the difference in median attack rate was not significant (p = 0.10). There were no significant effects of DCP on muscle strength or muscle mass in either trial. The most common adverse events in both trials were paresthesia (47% DCP vs 14% placebo, both trials combined) and confusion (19% DCP vs 7% placebo, both trials combined).
CONCLUSIONS: DCP is effective in reducing the attack frequency, is safe, and improves quality of life in HOP periodic paralysis.
CLASSIFICATION OF EVIDENCE: These studies provide Class I evidence that DCP significantly reduces attack frequency in HOP but lacked the precision to support either efficacy or lack of efficacy of DCP in HYP.
PMID: 26865514 [PubMed - as supplied by publisher]

A Case of Nonfatal Ventricular Arrhythmia Due to Thyrotoxic Periodic Paralysis in a Saudi Patient as an Initial Presentation of Graves' Disease. Hakami O, Ahmad MM, Al Johani N. Clin Med Insights Case Rep. 2016 Jan 28;9:5-9. doi: 10.4137/CCRep.S34560. 

Thyrotoxic periodic paralysis (TPP) is a potentially lethal complication of hyperthyroidism characterized by recurrent muscle weakness and hypokalemia. It has been commonly reported in non-Asian populations. Four cases were reported in Saudis so far, and one had a life-threatening arrhythmia. We describe an additional case of a 28-year-old apparently healthy Saudi male patient, who presented with acute paraparesis associated with hypokalemia (K: 2.0 mmol/L), complicated by ventricular tachycardia and cardiac arrest. He was successfully resuscitated and his hypokalemia was corrected. A diagnosis of Graves' disease associated with TPP was made. He was initially treated with carbimazole and β-blockers and then given a definitive therapy with radioactive iodine, which showed a good response. This case highlights the importance of early recognition and prompt treatment of TPP as a differential diagnosis for muscle weakness. A brief review of TPP and associated arrhythmia is included. PMID: 26843815 [PubMed] PMCID: PMC4734662

Severe Hypokalemic Paralysis as a Manifestation of a Mitochondrial Disorder. Josef Finsterer and Stefan Lässer; Tohoku J. Exp. Med., 2013, 231, 9-12

Mitochondrial disorder (MtD) is usually a multisystem disease due to impaired mitochondrial energy production. Severe hypokalemia resulting in muscle weakness and rhabdomyolysis has not been reported as a phenotypic feature of Mitochondrial Disease. …Mitochondrial disorder (MtD) is most frequently due to impaired energy production by the respiratory chain or the oxidative phosphorylation. The biochemical defect may result from mutations in the mitochondrial DNA or the nuclear DNA. MtD may manifest as a syndromic or non-syndromic disorder, or as a mono-organ or multi-organ disease (Finsterer 2012). read article

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