Treatment for Lambert-Eaton myasthenic syndrome

Structure-activity relationship studies of four novel 4-aminopyridine K+ channel blockers

4-Aminopyridine (4AP) is a specific blocker of voltage-gated potassium channels (K_V1 family) clinically approved for the symptomatic treatment of patients with multiple sclerosis (MS). It has recently been shown that [¹⁸F]3F4AP, a radiofluorinated analog of 4AP, also binds to K_V1 channels and can be used as a PET tracer for the detection of demyelinated lesions in rodent models of MS. Here, we investigate four novel 4AP derivatives containing methyl (-CH₃), methoxy (-OCH₃) as well as trifluoromethyl (-CF₃) in the 2 and 3 position as potential candidates for PET imaging and/or therapy. We characterized the physicochemical properties of these compounds (basicity and lipophilicity) and analyzed their ability to block Shaker K⁺ channel under different voltage and pH conditions. Our results demonstrate that three of the four derivatives are able to block voltage-gated potassium channels. Specifically, 3-methyl-4-aminopyridine (3Me4AP) was found to be approximately 7-fold more potent than 4AP and 3F4AP; 3-methoxy- and 3-trifluoromethyl-4-aminopyridine (3MeO4AP and 3CF₃4AP) were found to be about 3- to 4-fold less potent than 4AP; and 2-trifluoromethyl-4-AP (2CF₃4AP) was found to be about 60-fold less active. These results suggest that these novel derivatives are potential candidates for therapy and imaging.

Development of a PET radioligand for potassium channels to image CNS demyelination

Central nervous system (CNS) demyelination represents the pathological hallmark of multiple sclerosis (MS) and contributes to other neurological conditions. Quantitative and specific imaging of demyelination would thus provide critical clinical insight. Here, we investigated the possibility of targeting axonal potassium channels to image demyelination by positron emission tomography (PET). These channels, which normally reside beneath the myelin sheath, become exposed upon demyelination and are the target of the MS drug, 4-aminopyridine (4-AP). We demonstrate using autoradiography that 4-AP has higher binding in non-myelinated and demyelinated versus well-myelinated CNS regions, and describe a fluorine-containing derivative, 3-F-4-AP, that has similar pharmacological properties and can be labeled with ¹⁸F for PET imaging. Additionally, we demonstrate that [¹⁸F]3-F-4-AP can be used to detect demyelination in rodents by PET. Further evaluation in Rhesus macaques shows higher binding in non-myelinated versus myelinated areas and excellent properties for brain imaging. Together, these data indicate that [¹⁸F]3-F-4-AP may be a valuable PET tracer for detecting CNS demyelination noninvasively.

Use of Cellular and Plasma Apheresis in the Critically Ill Patient: Part II: Clinical Indications and Applications

Apheresis is the process of separating the blood and removing or manipulating a cellular or plasma component for therapeutic benefit. Such procedures may be indicated in the critical care setting as primary or adjunctive therapy for certain hematologic, neurologic, renal, and autoimmune/rheumatologic disorders. In part I of this series, the technical aspects of apheresis were described and the physiologic rationale and clinical considerations were discussed. This review highlights the pathophysiologic basis, specific clinical indications, and treatment parameters for disorders that more commonly require management in the intensive care unit. The choice of plasma or cellular apheresis in these cases is guided by wellaccepted, evidence-based clinical treatment guidelines. For some disorders, such as liver failure, severe sepsis, and multiple-organ dysfunction syndrome, apheresis treatment approaches remain experimental. Ongoing studies are investigating the potential utility of conventional plasma exchange, ex vivo plasma manipulation, and newer technologies for these and other disorders in severely ill patients.

Lambert-Eaton myasthenic syndrome as a cause of persistent neuromuscular weakness after a mediastinoscopic biopsy -A case report-

There are many causes of prolonged postoperative muscle weakness, including drugs, residual anesthetics, cerebrovascular events, electrolyte imbalance, hypothermia, and neuromuscular disease. Neuromuscular diseases are relatively rare, with the most common being myasthenia gravis and Lambert-Eaton myasthenic syndrome (LEMS). We report an unusual case in which a patient who was given a muscle relaxant during mediastinoscopy developed postoperative muscle weakness that was ultimately diagnosed as secondary to LEMS.

Use of non-specific intravenous human immunoglobulins in Spanish hospitals; need for a hospital protocol

Intravenous immunoglobulin (IVIG) use in non-approved indications, the increase in consumption and its high cost recommend rationalisation in its utilisation.

AIMS

To assess the use of IVIG in Spanish hospitals.

METHODS

An observational, prospective and multicentre drug utilisation study was conducted in 13 tertiary Spanish hospitals. Data were collected for 3 months in patients receiving any IVIG. Patient demographics, indication for IVIG use, dosage regimen and cost of treatment were collected.

RESULTS

Five hundred and fifty-four patients (mean age of 52 years) were included in the study. A total of 1,287 prescriptions were administered, and the average number of prescriptions per patient was 2.3. The mean daily dose was 24 g (range 0.6-90 g). Overall, IVIG was prescribed for authorised indications in 335 patients (60%) with 953 prescriptions (74%), for non-authorised indications with scientific evidentiary support in 86 patients (16%) with 137 prescriptions (11%), and non-authorised and non-accepted indications in 133 patients (24%) with 197 prescriptions (15%). The most frequent authorised indications were primary and secondary immunodeficiencies, and the most frequent non-authorised and non-accepted indications were multiple sclerosis and bullous dermatosis. The mean cost of IVIG per patient for authorised indications was 2,636.2 <euro>, non-authorised indications with scientific support 5,262.1 <euro> and non-accepted indications 3,555.8 <euro>.

CONCLUSIONS

IVIG is prescribed for a significant number of non-authorised and non-accepted indications with a notable cost. There is an important variability in IVIG prescriptions between hospitals, indicating room for improvement in IVIG use and the need for a consensus of protocol use.