Metadate, Ritalin, and Concerta are stimulant medications employed in the treatment of Attention Deficit Hyperactivity Disorder. They all are forms of methylphenidate and have essentially the same side effect profile. Side effects can include appetite suppression, onset insomnia (more likely if the medication is taken later in the day so that it has not been metabolized by 8:00 pm or so), some stomach upset if not taken with food, motor tics (usually involving the facial muscles), headache, unusual thinking, and irritability.
As you may already know, secretin is one of the body's neurotransmitters, commonly referred to as chemical messengers. Secretin is one of the chemicals that controls digestion. In research conducted to investigate digestion, it was noted that the substance yielded some benefits in behavior - e.g., increased alertness, better eye contact, improvement in expressive language. However, controlled studies have been few, and they have not been encouraging relative to expected benefits for children diagnosed with disorders along the PDD spectrum, particularly autism. Synthetic secretin has been produced for the purpose of research - it is not approved for other use.