Use of acetazolamide in sulfonamide-allergic patients with neurologic channelopathies

Elucidating the combined effect of intermittent hypoxia training and acetazolamide on hypoxia induced hematological and physiological changes

As the number of people travelling to altitude increases, the risk of life threatening medical emergencies also increases. It is important that we have effective strategies to minimize the risk of altitude illness. In this study, an attempt was made to investigate the combined effect of non-pharmacological (Intermittent hypoxia training; IHT) and pharmacological (acetazolamide; ACZ) intervention as a prophylactic strategy in order to minimize the risk of high altitude hypoxic related problems using rats as an animal model. Male Sprague Dawley rats were subjected to IHT for 4 h consecutively for 5 days at 12% FiO₂ under normobaric conditions with and without oral ACZ administration at 25 mg/kg body weight. Validation of the intervention was performed by exposing the rats to extreme hypoxia (EH) at 8% FiO₂ to further assess the effect of IHT and ACZ on hypoxic acclimatization. The principal findings of this study is that the combined effect of IHT and ACZ improves the arterial oxygenation by alterations in hemodynamics and in blood gasometry, thereby resulting into an increase in the oxygen carrying capacity of the blood with increase in SpO₂ (peripheral oxygen saturation). The present study showed that the combined effect of IHT with ACZ could be refined as a prophylactic measure for better outcomes during altitude ascent and rapid altitude acclimatization rather than IHT or ACZ alone.

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Combination of IHT with ACZ attenuates the inhibitory effect of respiratory alkalosis.

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It also minimizes pathological changes in hematology and blood gas.

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The strategy improved the oxygen carrying capacity of the blood by increasing SpO₂.

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Thus, it leads to ventilatory Acclimatization.

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The combined treatment could be refined as a prophylactic measure for altitude maladies.

Fixed-combination topical anti-hypertensive ophthalmic agents

INTRODUCTION

Fixed-combination glaucoma medications have altered the paradigm of ocular hypertension and glaucoma treatment and are in widespread use today. A comprehensive review of fixed-combination medications will help educate and inform providers for optimal patient care.

AREAS COVERED

In this review, the authors describe the composition, mechanism of action, efficacy, side effects, and safety profile of fixed-combination agents for the treatment of ocular hypertension and glaucoma as well as comparisons between the most frequently prescribed medications.

EXPERT OPINION

Fixed-combination therapeutics provide an effective and efficient means of lowering intraocular pressure with comparable side effects and outcomes to constituent parts with lower patient exposure to preservatives and improvement in compliance.

An old lady with acute headache and sudden blindness

A 60-year-old hypertensive lady experienced painless sudden visual loss in the right eye when resting at home. There was no traumatic injury, no eye pain, or flashes or floaters, or nausea, but mild right-sided headache for few days. She was not lifting heavy objects, nor straining. She managed to attend the emergency department within 1 h of onset of symptoms by herself walking into the consultation room unaided. Examination showed visual acuity with pinhole of hand movement over the right eye, right relative afferent pupillary defect and normal intraocular pressure of 15 mmHg. Extraocular movement was full without diplopia or pain. Eyes were not injected, and slit lamp examination was normal with clear cornea. Acute management of vascular causes of acute blindness and the role of hyperbaric oxygen therapy in ophthalmological disease in Hong Kong will be discussed.

Contemporary management of the pseudotumor cerebri syndrome

Introduction: Diagnosis and appropriate management of patients with the pseudotumor cerebri syndrome are imperative to prevent or minimize permanent visual loss and headache-related disability. Areas covered: Steps in management, including making the correct diagnosis, techniques to assess the patient's visual status, medical treatment of intracranial hypertension and the associated headaches, weight management strategies, surgical treatments and stenting are reviewed incorporating the most recent medical evidence. Expert opinion: As the pathogenesis of the pseudotumor cerebri syndrome is still unknown, many of the currently employed management strategies incorporate a 'plumbing approach' to decrease cerebrospinal fluid (CSF) pressure. The Idiopathic Intracranial Hypertension Trial (IIHTT) taught us that the disorder markedly affects visual and overall quality of life, and that reducing pressure alone is not enough to make patients well, even those considered to have 'mild' vision loss. Other than the IIHTT, the evidence supporting the use of various treatments is meager. The course of the disorder can be unpredictable, and the clinician(s) managing these patients are often uncertain about which treatments to employ. Moreover, the desired modalities and specialists are not universally available in all locations. An individualized and detailed approach to the various manifestations and nuances of the disorder is essential.

Systematic analysis and identification of unexpected interactions from the neuroprotein drug interactome in hydrocephalus pharmacological intervention

Hydrocephalus is a neurological condition caused by an abnormal accumulation of cerebrospinal fluid; pharmacological intervention of the disease has been found to elicit a variety of adverse drug reactions (ADRs) in central nervous system (CNS) by unexpectedly targeting certain functional neuroproteins. Here, a systematic neuroprotein drug interactome (SNDI) is created for 11 hydrocephalus drugs/metabolites plus 20 control drugs across 518 druggable pockets on the surface of 472 CNS neuroproteins via a large-scale molecular docking approach. Heuristic clustering analysis of the SNDI profile divides the 31 investigated drug ligands into a distinct panel and a background panel; the former consists of two hydrocephalus drugs (Furosemide and Triamterene) and their respective metabolites (Furosemide glucuronide and Hydroxytriamterene) that are inferred to have generally high affinity towards the whole array of neuroprotein pockets. A total of 13 neuroproteins are enriched in gene ontology semantic mining as putative unexpected targets of the distinct panel, and their intermolecular interactions with hydrocephalus drugs/metabolites are investigated in detail using dynamics simulation and energetics analysis. We also perform kinase assay and viability test to substantiate the interactome analysis. It is found that the Furosemide and Triamterene have significant cytotoxic effects on normal human astrocytes, in which the Triamterene can inhibit the neurokinase ROCK2, a representative of putative unexpected targets, with a high activity, which is comparable with the sophisticated ROCK2 inhibitor Fasudil.

Therapy of episodic ataxias: case report and review of the literature

Episodic ataxias (EAs) are characterized by recurrent, discrete episodes of vertigo and ataxia. EA1 and EA2 are the two most common forms. In the interictal interval, myokymia is typically present in EA1, whereas EA2 patients present with interictal nystagmus. Specific pharmacological therapies are available for EA1 and especially EA2. We briefly discuss the case of an Italian young man with EA2, with a novel de novo CACNA1A mutation, who in our opinion is particularly illustrative for introducing the therapeutic approach. Acetazolamide could fully suppress EA episodes in our patient. We also provide a perspective review of the topic. 4-Aminopyridine is another valid treatment option. For EA1 (and for rarer EAs), the therapeutic possibilities are more limited. Carbamazepine is probably the treatment of choice for EA1, but the optimal treatment plan is unknown. A better understanding of the molecular processes involved in the mediation of EAs will lead to more specific and efficacious therapies for this still elusive group of disorders.

Neuroimaging of vascular reserve in patients with cerebrovascular diseases

Cerebrovascular reactivity, defined broadly as the ability of brain parenchyma to adjust cerebral blood flow in response to altered metabolic demand or a vasoactive stimulus, is being measured with increasing frequency and may have a use for portending new or recurrent stroke risk in patients with cerebrovascular disease. The purpose of this review is to outline (i) the physiological basis of variations in cerebrovascular reactivity, (ii) available approaches for measuring cerebrovascular reactivity in research and clinical settings, and (iii) clinically-relevant cerebrovascular reactivity findings in the context of patients with cerebrovascular disease, including atherosclerotic arterial steno-occlusion, non-atherosclerotic arterial steno-occlusion, anemia, and aging. Literature references summarizing safety considerations for these procedures and future directions for standardizing protocols and post-processing procedures across centers are presented in the specific context of major unmet needs in the setting of cerebrovascular disease.

"Doctor, I have a Sulfa Allergy": Clarifying the Myths of Cross-Reactivity

Our purpose is to present an evidence-based approach, directed primarily towards eye-care specialists, clarifying whether certain drugs should or should not be used in patients with sulfonamide allergy. We conducted a literature search using PubMed to identify the risk of ophthalmic-specific drugs in patients with a self-reported sulfonamide allergy. MeSH key words included "sulfonamide" and "hypersensitivity". Articles specifically geared towards ophthalmic diseases were sought. The evidence illustrates that individuals with sulfonamide allergy are intrinsically predisposed to higher rates of allergic reaction that is not specific towards sulfonamide non-antimicrobials or sulfur-based medications. We provide a simplified algorithm using the 2017 Clinical Guide to Ophthalmic Drugs to help busy eye care clinicians determine whether a certain common ophthalmic medication is safe or unsafe to prescribe in a patient with a "sulfa allergy".

Sulfonamide Drug Allergy

PURPOSE OF REVIEW

We sought to review past and current literature on sulfonamide drug allergy and distill it in a practical manner to assist the clinician, specifically focusing on cross-reactivity and desensitization.

RECENT FINDINGS

There do not appear to be consistent genetic markers to reliably predict features of or the presence hypersensitivity reactions. Recent evidence continues to alleviate early concerns cross-reactivity between sulfonamide antibiotics and non-antibiotics. Sulfonamide drug allergy is frequently encountered by the practicing clinician. For sulfonamide antibiotics, delayed rash is the most common clinical manifestation. There is no current evidence to support avoidance of all non-antibiotic sulfonamides in those with a reported allergy to sulfonamide antibiotics, although certain scenarios require caution. Available evidence supports the cautious reintroduction of sulfonamide antibiotics via desensitization, which is usually well tolerated and should be considered in those with strong indications for trimethoprim-sulfamethoxazole and a reported sulfonamide allergy.

Safety and Tolerability of Acetazolamide in the Idiopathic Intracranial Hypertension Treatment Trial

OBJECTIVE

To examine the tolerability and adverse events reported in the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT).

METHODS

Randomized, double-masked, placebo-controlled clinical trial. Trial participants (n = 165) with mild visual loss concurrently receiving low-sodium weight-reduction diet plus the maximally tolerated dosage of acetazolamide (up to 4 g/d) or placebo for 6 months.

MAIN OUTCOMES MEASURES

adverse events (AEs), assessment of clinical and laboratory findings at study visits.

RESULTS

Thirty-eight of 86 participants randomized to the acetazolamide group (44.1%) tolerated the maximum allowed dosage of 4 g/d. The average time to achieve maximum study dosage in the acetazolamide group was 13 weeks (median 12 weeks; range 10-24 weeks). A total of 676 AEs (acetazolamide, n = 480; placebo, n = 196) and 9 serious AEs (acetazolamide, n = 6; placebo, n = 3) were reported. Notably, the percentages of participants reporting at least 1 AE in the nervous, gastrointestinal, metabolic, and renal organ systems were significantly higher in the acetazolamide group (P < 0.05). The odds of paresthesia (OR 9.82; 95% CI 3.87-27.82), dysgeusia (OR ∞; 95% CI 3.99-∞), vomiting and diarrhea (OR 4.11; 95% CI 1.04-23.41), nausea (OR 2.99; 95% CI 1.26-7.49) and fatigue (OR 16.48; 95% CI 2.39-702.40) were higher in the acetazolamide group than in the placebo group.

CONCLUSION

Acetazolamide appears to have an acceptable safety profile at dosages up to 4 g/d in the treatment of idiopathic intracranial hypertension. The majority of participants in the Idiopathic Intracranial Hypertension Treatment Trial were able to tolerate acetazolamide above 1 g/d for 6 months.