Investigation of the Efficacy of Acamprosate and Calcium in Comparison to Placebo as Validation of a Behavioural Test for Alcohol Dependence

Inclusion Criteria:

1. male and female volunteers aged 25 to 55 years, who meet or met the diagnosticcriteria of an at least mild alcohol use disorder (DSM-5), but do not want to ceasealcohol consumption

2. willingness to stop alcohol and drug consumption for 15-20 days for the purpose ofstudy participation

3. at least high risky alcohol drinkers (WHO) in the Timeline Follow-back Interviewover the last 45 day with an average amount of alcohol of 60 g/day (men) or 40 g/day (women) with at least 4 drinking days per week

4. informed consent

5. ability to swallow a placebo capsule

6. not more than 6 consecutive alcohol abstinent days between screening and visit 2

Exclusion Criteria:

1. Current Substance dependence (illegal drugs) ICD-10 or DSM-IV

2. Intention to stop alcohol consumption immediately and permanently

3. Current or previous disease that could cause a clinically relevant hazard (e.g.pancreatitis, cirrhosis)

4. kidney stone disease

5. Current Treatment with psychotropic drugs or current psychiatric disorder in need oftreatment

6. alcohol withdrawal symptoms (at Screening, visit 1 or visit 2) with CIWA-Ar-Score > 6 points or arterial blood pressure >160 mm Hg or diastolic blood pressure > 100 mmHg or heart rate >105 bpm (when breath alcohol concentration 0 mg%)

7. history of epileptic seizure or delirium

8. routine laboratory parameters, indicating relevant liver-, pancreas- or kidneyinjury, an acute infection, anemia or lack of vitamins (ASAT, ALAT, lipase >threefold of the standard at screening, Quick's value < 70%, creatinine > 120 µmol/l, eGFR < 30 mol/min/1.73 m², leucocytes > 13000/µl, haemoglobin < 7.5 mmol/l (men) or 6.5 mmol/l (women), MCV > 105 fl, calcium level at screening > 2.7 mmol/l

9. body weight > 120 kg (Screening)

10. Breath alcohol concentration at screening or visit 1 or visit 2 two times > 0 mg% ordrug screening two times positive for opiate, cannabis, cocaine, amphetamine,benzodiazepine

11. history of hypersensitivity to alcohol or one of the used medicinal products, oftheir ingredients or medicinal products with similar chemical structures

12. history of inefficient treatment with Acamprosate

13. participation in another clinical trial within the last 4 weeks before inclusion

14. disorders, which will not allow the subject to assess the character and importanceor possible consequences of the clinical trial

15. pregnant or breastfeeding women

16. women capable of bearing children, except women who fulfil following criteria:-post-menopausal (12 months natural amenorrhoea or 6 month amenorrhoea and Serum FSH >40 ml U/ml) - post operative (6 weeks after ovariectomy on both sides with orwithout hysterectomy) - regular and correct use of a contraceptive method with anerror Quote of < 1 % per year (for example implants, depot injections, oralcontraceptive, IUP). It has to be recognized that a combined oral contraception - incontrast to pure progesterone compounds - have a failure rate of < 1 %. Hormone IUDswith a Pearl Index of 1 % are safer than copper IUDs. - sexual abstinence -vasectomy of the Partner)

17. participant is not expected to comply with the protocol (for example lackingcompliance)

18. less than 200 cumulative work trials for alcohol (in constant attention task) on 1stalcohol self-administration day

19. specific contraindications for Acamprosate or Calcium Carbonate (accordingprescribing information)

20. hypercalcemia, e.g. due to hyperparathyroidism, overdosage vitamin D,paraneoplastic

21. renal insufficiency (eGFR < 30ml/min/1.73m²), creatinine >120 µmol/l

22. intake of Vitamin D compounds or cardioactive glycosides