This clinical study is designed to evaluate the safety and tolerability of a single oral administration of a Metadoxine slow release formulation to subjects diagnosed as having ADHD. Study also assess cognitive effects of such drug administration.

Primary outcome measure is the safety and tolerability of study drug after a single dosing.

Additional outcomes include commission error rate from the TOVA test. The result is measured as standard score in % compared to the values of the normal population.

Exploratory outcome measures include:

1. TOVA measures like response time , variability, omissions etc.
2. Subtests from Wechsler: digit memory, digit-number signs etc

Inclusion Criteria:

• age 18-45
• diagnosed as ADHD

Exclusion Criteria:

• PDD patients
• head injured patients
• patients suffering from heart, lung, liver, kidney, intestinal, endocrine an neurological diseases and patients who are sensitive to vitamin B