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CPT: Pharmacometrics & Systems... Sep 2017Lambert-Eaton myasthenia (LEM) is a rare autoimmune disorder associated with debilitating muscle weakness. There are limited treatment options and 3,4-diaminopyridine... (Randomized Controlled Trial)
Randomized Controlled Trial
Lambert-Eaton myasthenia (LEM) is a rare autoimmune disorder associated with debilitating muscle weakness. There are limited treatment options and 3,4-diaminopyridine (3,4-DAP) free base is an investigational orphan drug used to treat LEM-related weakness. We performed a population pharmacokinetic/pharmacodynamic (PK/PD) analysis using 3,4-DAP and metabolite concentrations collected from a phase II study in patients with LEM. The Triple Timed Up & Go (3TUG) assessment, which measures lower extremity weakness, was the primary outcome measure. A total of 1,270 PK samples (49 patients) and 1,091 3TUG data points (32 randomized patients) were included in the PK/PD analysis. A two-compartment and one-compartment model for parent and metabolite, respectively, described the PK data well. Body weight and serum creatinine partially explained the variability in clearance for the final PK model. A fractional inhibitory maximum effect (E ) model characterized the exposure-response relationship well. The PK/PD model was applied to identify a suggested dosing approach for 3,4-DAP free base.
Topics: 4-Aminopyridine; Adult; Aged; Aged, 80 and over; Amifampridine; Arylamine N-Acetyltransferase; Female; Humans; Lambert-Eaton Myasthenic Syndrome; Lower Extremity; Male; Middle Aged; Models, Biological; Muscle Weakness; Polymorphism, Single Nucleotide; Potassium Channel Blockers; Treatment Outcome; Young Adult
PubMed: 28623849
DOI: 10.1002/psp4.12218 -
Scientific Reports May 20244-aminopyridine (4AP) is a potassium (K) channel blocker used clinically to improve walking in people with multiple sclerosis (MS). 4AP binds to exposed K channels in...
4-aminopyridine (4AP) is a potassium (K) channel blocker used clinically to improve walking in people with multiple sclerosis (MS). 4AP binds to exposed K channels in demyelinated axons, reducing the leakage of intracellular K and enhancing impulse conduction. Multiple derivatives of 4AP capable of blocking K channels have been reported including three radiolabeled with positron emitting isotopes for imaging demyelinated lesions using positron emission tomography (PET). However, there remains a demand for novel molecules with suitable physicochemical properties and binding affinity that can potentially be radiolabeled and used as PET radiotracers. In this study, we introduce 3-fluoro-5-methylpyridin-4-amine (5Me3F4AP) as a novel trisubstituted K channel blocker with potential application in PET. 5Me3F4AP has comparable potency to 4AP and the PET tracer 3-fluoro-4-aminopyridine (3F4AP). Compared to 3F4AP, 5Me3F4AP exhibits comparable basicity (pK = 7.46 ± 0.01 vs. 7.37 ± 0.07, P-value = 0.08), greater lipophilicity (logD = 0.664 ± 0.005 vs. 0.414 ± 0.002, P-value < 0.0001) and higher permeability to an artificial brain membrane (P = 88.1 ± 18.3 vs. 31.1 ± 2.9 nm/s, P-value = 0.03). 5Me3F4AP is also more stable towards oxidation in vitro by the cytochrome P450 enzyme CYP2E1 (IC = 36.2 ± 2.5 vs. 15.4 ± 5.1, P-value = 0.0003); the enzyme responsible for the metabolism of 4AP and 3F4AP. Taken together, 5Me3F4AP has promising properties as a candidate for PET imaging warranting additional investigation.
Topics: Potassium Channel Blockers; Humans; Positron-Emission Tomography; 4-Aminopyridine; Amifampridine
PubMed: 38750155
DOI: 10.1038/s41598-024-61465-w -
Zhongguo Yao Li Xue Bao = Acta... Jan 1991We used 3,4-diaminopyridine (3,4-DAP) and 4-aminopyridine (4-AP) as stimuli for evoking [3H]norepinephrine ([3H]NE) release in rabbit hippocampal slices to investigate...
We used 3,4-diaminopyridine (3,4-DAP) and 4-aminopyridine (4-AP) as stimuli for evoking [3H]norepinephrine ([3H]NE) release in rabbit hippocampal slices to investigate the mechanism underlying the aminopyridines evoked [3H]NE release and the effect of protein kinase C activator phorbol ester PDB. 3,4-DAP and 4-AP evoked [3H]NE release were concentration dependent and enhanced by phorbol ester PDB. 4-AP (300 mumol.L-1) evoked [3H]NE release and enhancement of this evoked release by PDB were antagonized by protein kinase C inhibitor polymyxin B and almost abolished by tetrodotoxin. N-ethylmaleimide inhibited the facilitatory effect of PDB on 3,4-DAP evoked [3H]NE release implicating that G-protein is involved in the modulation of evoked [3H]NE release. 3,4-DAP evoked also dopamine release in caudate nucleus, and acetylcholine release in hippocampus suggesting that the mechanism by which 3,4-DAP evoked transmitters release is similar to that of electrical stimulation.
Topics: 4-Aminopyridine; Amifampridine; Animals; Female; Hippocampus; Male; Norepinephrine; Phorbol 12,13-Dibutyrate; Polymyxin B; Rabbits
PubMed: 1950580
DOI: No ID Found -
Neuropsychiatric Disease and Treatment 2011In Lambert-Eaton myasthenic syndrome (LEMS), antibodies against presynaptic voltage-gated calcium channels reduce the quantal release of acetylcholine, causing muscle...
In Lambert-Eaton myasthenic syndrome (LEMS), antibodies against presynaptic voltage-gated calcium channels reduce the quantal release of acetylcholine, causing muscle weakness and autonomic dysfunction. More than half of the affected patients have associated small cell lung cancer, and thorough screening for an underlying malignancy is crucial. The mainstay of treatment for LEMS is symptomatic but immunotherapy is needed in more severely affected patients. Symptomatic therapies aim at increasing the concentration of acetylcholine at the muscle endplate. While acetylcholinesterase inhibitors were the first drugs to be used for the amelioration of symptoms, 3,4-diaminopyridine (3,4-DAP, amifampridine) has been shown to be more effective. 3,4-DAP blocks presynaptic potassium channels, thereby prolonging the action potential and increasing presynaptic calcium concentrations. This then results in increased quantal release of acetylcholine. The efficacy of 3,4-DAP for increasing muscle strength and resting compound muscle action potentials has been demonstrated by four placebo-controlled trials. Side effects are usually mild, and the most frequently reported are paresthesias. The most common serious adverse events are epileptic seizures. 3,4-DAP is currently the treatment of choice in patients with Lambert-Eaton myasthenic syndrome.
PubMed: 21822385
DOI: 10.2147/NDT.S10464 -
The Journal of Pharmacology and... Jan 2024Botulinum neurotoxin (BoNT) is a potent protein toxin that causes muscle paralysis and death by asphyxiation. Treatments for symptomatic botulism are intubation and...
Botulinum neurotoxin (BoNT) is a potent protein toxin that causes muscle paralysis and death by asphyxiation. Treatments for symptomatic botulism are intubation and supportive care until respiratory function recovers. Aminopyridines have recently emerged as potential treatments for botulism. The clinically approved drug 3,4-diaminopyridine (3,4-DAP) rapidly reverses toxic signs of botulism and has antidotal effects when continuously administered in rodent models of lethal botulism. Although the therapeutic effects of 3,4-DAP likely result from the reversal of diaphragm paralysis, the corresponding effects on respiratory physiology are not understood. Here, we combined unrestrained whole-body plethysmography (UWBP) with arterial blood gas measurements to study the effects of 3,4-DAP, and other aminopyridines, on ventilation and respiration at terminal stages of botulism in mice. Treatment with clinically relevant doses of 3,4-DAP restored ventilation in a dose-dependent manner, producing significant improvements in ventilatory parameters within 10 minutes. Concomitant with improved ventilation, 3,4-DAP treatment reversed botulism-induced respiratory acidosis, restoring blood levels of CO, pH, and lactate to normal physiologic levels. Having established that 3,4-DAP-mediated improvements in ventilation were directly correlated with improved respiration, we used UWBP to quantitatively evaluate nine additional aminopyridines in BoNT/A-intoxicated mice. Multiple aminopyridines were identified with comparable or enhanced therapeutic efficacies compared with 3,4-DAP, including aminopyridines that selectively improved tidal volume versus respiratory rate and vice versa. In addition to contributing to a growing body of evidence supporting the use of aminopyridines to treat clinical botulism, these data lay the groundwork for the development of aminopyridine derivatives with improved pharmacological properties. SIGNIFICANCE STATEMENT: There is a critical need for fast-acting treatments to reverse respiratory paralysis in patients with botulism. This study used unrestrained, whole-body plethysmography and arterial blood gas analysis to show that aminopyridines rapidly restore ventilation and respiration and reverse respiratory acidosis when administered to mice at terminal stages of botulism. In addition to supporting the use of aminopyridines as first-line treatments for botulism symptoms, these data are expected to contribute to the development of new aminopyridine derivatives with improved pharmacological properties.
Topics: Mice; Humans; Animals; Botulism; Aminopyridines; Amifampridine; Acidosis, Respiratory; Botulinum Toxins, Type A; Paralysis; Respiration
PubMed: 37977816
DOI: 10.1124/jpet.123.001773 -
BMC Neurology Sep 2021Lambert-Eaton myasthenic syndrome (LEMS) is a rare autoimmune disorder of neuromuscular transmission. The objective was to examine the efficacy and safety of... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Lambert-Eaton myasthenic syndrome (LEMS) is a rare autoimmune disorder of neuromuscular transmission. The objective was to examine the efficacy and safety of 3,4-diaminopyridine (3,4-DAP) in patients with LEMS.
METHODS
We searched several databases to identify relevant studies, including PubMed, EMBASE, Web of Science, MEDLINE, Cochrane Neuromuscular Disease Group Specialized Register and the Cochrane Central Register of Controlled Trials(CENTRAL). The primary outcome, quantitative myasthenia gravis (QMG) score and the secondary outcome, compound muscle action potentials (CMAP) amplitude were pooled by meta-analysis.
RESULTS
Six randomised controlled trials (RCTs) involving 115 patients with LEMS were included. QMG score showed a significant decrease (improvement) of 2.76 points (95 % CI, -4.08 to -1.45, p < 0.001) after treatment with 3, 4-DAP. Moreover, the overall mean CMAP amplitude improved significantly in LEMS patients with 3, 4-DAP treatment, compared with placebo treatment (mean difference 1.34 mV, 95 % CI, 0.98 to 1.70, p < 0.001). The overall assessment of all included trials showed a low risk of bias and low heterogeneity.
CONCLUSIONS
The pooled results of RCTs demonsrated with moderate to high evidence that 3,4-DAP has a significant effect on LEMS treatment, with improvements in muscle strength score and CMAP amplitude.
Topics: 4-Aminopyridine; Adult; Amifampridine; Humans; Lambert-Eaton Myasthenic Syndrome; Myasthenia Gravis; Randomized Controlled Trials as Topic
PubMed: 34563155
DOI: 10.1186/s12883-021-02405-3 -
Cureus Jan 2024After a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, approximately 10-20% of patients are affected by the post-COVID syndrome (PCS). This...
After a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, approximately 10-20% of patients are affected by the post-COVID syndrome (PCS). This condition leads to a variety of functional complaints, including symptoms of fatigue. To date, there is still no adequate treatment option. Five patients are presented, including the self-observation of one of the authors, in whom the administration of amifampridine as an "off-label use" led to a normalization of the unphysiologically increased need for sleep with a simultaneous increase in the Bell score. This effect was confirmed in a double-blind discontinuation trial (the medication was discontinued on a trial basis) in two of the patients. The five patients, who were previously unable to lead a normal life due to their fatigue symptoms, were able to return to everyday life after treatment with amifampridine. This offers hope to millions of affected patients.
PubMed: 38406122
DOI: 10.7759/cureus.52935 -
The Journal of Physiology Oct 19901. Intracellular recordings were made from neurones of the guinea-pig gall-bladder in vitro. Intracellular injection of horseradish peroxidase revealed a simple...
1. Intracellular recordings were made from neurones of the guinea-pig gall-bladder in vitro. Intracellular injection of horseradish peroxidase revealed a simple structure, consisting of a soma and a single process, but no discernible dendritic arborization. 2. The resting membrane potential was -50.5 +/- 0.4 mV and the input resistance was 80 M omega. 3. Gall-bladder neurones spiked only once at the onset of depolarizing current pulses. Action potentials were blocked by tetrodotoxin, but a Ca2(+)-dependent spike could be elicited in the presence of tetrodotoxin and tetraethylammonium. 4. Action potential after-hyperpolarizations had a duration of 172 +/- 3.7 ms and reversed at a membrane potential of -93 mV; this reversal potential was linearly related to the logarithm of the external potassium concentration. The initial phase of the after-hyperpolarization was inhibited by tetraethylammonium (1-10 mM) and was not affected by 3,4-diaminopyridine. The late phase of the after-hyperpolarization was blocked by apamin (10 nM) or curare (500 microM). Both the early and late phases of the after-hyperpolarization were inhibited when the preparation was perfused with a calcium-free, high-magnesium solution. The calcium-free, high-magnesium solution had no effect on the membrane potential or input resistance of these cells. 5. Fast excitatory synaptic responses and antidromic responses were elicited in gall-bladder neurones by focal stimulation of fibre tracts. High-frequency fibre tract stimulation often resulted in prolonged, calcium-dependent, depolarizations that were associated with a decrease in input resistance. 6. 5-Hydroxytryptamine and substance P caused depolarizations that were associated with a decrease in input resistance. Bethanechol caused hyperpolarizations that were associated with a decrease in input resistance and which were blocked by atropine.
Topics: 4-Aminopyridine; Action Potentials; Amifampridine; Animals; Apamin; Bethanechol; Bethanechol Compounds; Calcium; Curare; Gallbladder; Guinea Pigs; In Vitro Techniques; Membrane Potentials; Neurons; Serotonin; Substance P; Tetraethylammonium; Tetraethylammonium Compounds; Tetrodotoxin
PubMed: 1703571
DOI: 10.1113/jphysiol.1990.sp018259 -
The Journal of General Physiology Jul 1982The blocking action of 4-aminopyridine (4-AP) and 3, 4-diaminopyridine (Di-AP) on transient potassium current (IA) in molluscan central neurons was studied in internal...
The blocking action of 4-aminopyridine (4-AP) and 3, 4-diaminopyridine (Di-AP) on transient potassium current (IA) in molluscan central neurons was studied in internal perfusion voltage-clamp experiments. Identical blocking effects were seen when the drugs were applied either externally or internally. It was found that aminopyridines have two kinds of effects on IA channels. The first involves block of open channels during depolarizing pulses and results in a shortening of the time to peak current and an increase in the initial rate of decay of current. This effect of the drug is similar to the block of delayed potassium current by tetraethylammonium (TEA). The other effect is a steady block that increases in strength during hyperpolarization, is removed by depolarization, and is dependent on the frequency of stimulation. The voltage dependence of steady state block approximates the voltage dependence of inactivation gating a changes e-fold in approximately 10 mV. These data suggest that the strength of block may depend on the state of IA gating such that the resting state of the channel with open inactivation gate is more susceptible to block than are the open or inactivated states. A multistate sequential model for IA gating and voltage-dependent AP block is developed.
Topics: 4-Aminopyridine; Amifampridine; Aminopyridines; Animals; Electric Conductivity; In Vitro Techniques; Ion Channels; Membrane Potentials; Microelectrodes; Mollusca; Neural Inhibition; Neurons; Potassium
PubMed: 6288835
DOI: 10.1085/jgp.80.1.1 -
Medicine Sep 2017To report our experience on 7 patients (4 males and 3 females), affected by nonparaneoplastic Lambert-Eaton myasthenic syndrome, treated with 3,4-diaminopyridine...
RATIONALE
To report our experience on 7 patients (4 males and 3 females), affected by nonparaneoplastic Lambert-Eaton myasthenic syndrome, treated with 3,4-diaminopyridine phosphate (3,4-DAPP) either alone or in combination with other immunosuppressants or steroids.
PATIENT CONCERNS
Patients have been evaluated at specific timepoints (ie, baseline and last 5 year follow-up), with neurological examination, autoantibodies against presynaptic voltage-gated Cav2.1 (P/Q type) calcium ion channel (VGCC) dosage, neurophysiological evaluation focusing on the increased amplitude of the compound muscle action potential (cMAP) after maximum voluntary effort, quantitative myasthenia gravis (QMG) and activities of daily living scales, and autonomic nervous system involvement evaluation.
OUTCOMES
Five out of 7 patients presented a clinical improvement persisting at last 5-year follow-up; 2 out of them improved taking only 3,4-DAPP at the maximal dosage, whereas the remaining received concomitant medications, such as prednisone and azathioprine. However, the clinical amelioration was not statistically significant. No one of the patients reported severe adverse events, except one, complaining of transient chin and perioral paresthesias. A significant association between QMG and the type of pharmacological drugs therapy (P = .028) emerged. Indeed, we observed an improvement of the clinical condition in all 3 subjects treated with 3,4-DAPP and prednisone.
CONCLUSIONS
In this study, we confirm 3,4-DAPP treatment efficacy on muscle strength, but minor evidence of drug effectiveness have been demonstrated on the autonomic nervous system involvement and on the deep tendon reflexes reappearance, a part from patients who received 3,4-DAPP associated to prednisone.
Topics: 4-Aminopyridine; Activities of Daily Living; Adult; Amifampridine; Azathioprine; Drug Therapy, Combination; Female; Humans; Immunosuppressive Agents; Lambert-Eaton Myasthenic Syndrome; Male; Middle Aged; Muscle Strength; Prednisone; Severity of Illness Index; Treatment Outcome
PubMed: 28930822
DOI: 10.1097/MD.0000000000007839