Memory boost for cocaine users? small study tests potassium channel blocker

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Current diagnosis of mild, moderate, or severe CoUD according to DSM-5 * Minimum cocaine use of 1g/month in the last three months * Cocaine as the primary drug of consumption * Willingness to abstain from cocaine use at least 72 hours before prior to each study visit * Ability to read, understand and provide written informed consent * To be sufficiently fluent in German * Age between 20 and 50 years * Body mass index (BMI) between 19 and 30 kg/m2 * If applicable: luteal phase of the menstrual cycle * For individuals with childbearing potential: use of contraceptive measures Exclusion Criteria: * Presence or history of severe neurological disorders or head injuries * Current diagnosis of an acute or chronic infectious disease * If applicable: pregnancy and breastfeeding * Lifetime history of any epileptic seizures * Lifetime diagnosis of a cardiovascular disease, specifically arrhythmia and long QT syndrome * Clinically significant laboratory or ECG abnormality that could be a safety issue in the study * Lifetime diagnosis of liver or kidney disease including moderate or severe renal impairment (creatinine clearance \< 50 ml/min) * Known hypersensitivity or allergy to 4-aminopyridine * Use of potassium channel blockers within the last 3 months * Use of psychotropic medication within the last 7 days * Use of inhibitors of the organic cation transporter 2 (OCT2), such as cimetidine * Lifetime diagnosis of schizophrenia, bipolar disorder, obsessive-compulsive disorder, or autism spectrum disorder according to DSM-5 * Diagnosis of a current episode of depression * Current diagnosis of a moderate or severe substance use disorder other than CoUD according than DSM-5 * Daily cannabis consumption in the past three months * (E-Cigarette) Fagerström Test of Nicotine Dependence Score \> 5 (strong nicotine dependence) * Inability to follow the procedures of the study, e.g., due to language problems * Being related to or in any form dependent on the investigator * Prior participation (less than two years ago) in a study investigating working memory using the n-back task, the SWM, PAL, RVP, or LNST * Participation in another study with investigational drugs within the 30 days preceding and during the present study