Methylphenidate Hydrochloride (Ritalin)

Mechanism of Action: Methylphenidate is an amphetamine-like CNS stimulant that is believed to act by releasing dopamine and norepinephrine from CNS neurons.

Therapeutic Use: Treatment of attention deficit disorders (ADD) in children and narcolepsy (uncontrollable desire to sleep). Absorption: Well absorbed. Peak effect is 2 hours.

Metabolism: Metabolized in the liver and the metabolites are eliminated in the urine.

Half-life: 2 1/2 Hours.

Average Daily Dose (adult): 20-30 mg daily. In children, Ritalin should be initiated in small doses, with gradual weekly increments. Daily dosage above 60 mg is not recommended.

Adverse Effects: Nervousness, insomnia (disturbed sleep), loss of appetite, nausea, palpitations, dizziness and increase in blood pressure. Can trigger cardiac arrhythmias.

Drug Interaction: Use cautiously with drugs that increase blood pressure and MAO inhibitors. It may inhibit the metabolism of other drugs metabolized by the P-450 enzymes such as; coumadin, phenytoin and antidepressants. This would require a reduction in dose of the latter drugs.

Contraindication: Contraindicated for marked anxiety, tension, agitation, glaucoma (eye disease) and Tourette s syndrome. Safety in children under 6 years of age has not been established. Use with caution in patients with hypertension or seizure history.

References:

• Braha, R., Joyce, B., & Smith, L. (1999). Ritalin and neurobehavioral therapy in the treatment of low arousal following severe brain injury. Neurorehabilitation. 12(3), 201-204.
• Glenn, M. (1998). Methylphenidate for cognitive and behavioral dysfunction after traumatic brain injury. Journal of Head Trauma Rehabilitation. 13(5), 87-90.
  
• Kaelin, D., Cifu, D., & Matthies, B. (1996). Methylphenidate effect on attention deficit in the acutely brain-injured adult. Archives of Physical Medicine and Rehabilitation. 77(1), 6-9.
• Watanabe, M., Martin, E., et al. (1995). Successful Methylphenidate (Ritalin) treatment of apathy after subcortical infarcts. Journal of Neuropsychiatry and Clinical Neurosciences. 7(4), 502-504.
  
• Mooney, G.F. & Haas, L.J. (1993). Effect of methylphenidate on brain injury-related anger. Archives of Physical Medicine & Rehabilitation. 74, 153-160, Feb.
  Speech, T.J., Rao, S.M., Osmon, D.C., & Sperry, L.T. (1993). A double-blind controlled study of methylphenidate treatment in closed head injury.Brain Injury. 7(4), 333-338.
  
• Wroblewski, B., Glenn, M.B., Cornblatt, R., Joseph, A.B. et al (1993). Protriptyline as an alternative stimulant medication in patients with brain injury: A series of case reports.Brain Injury. 7(4), 353-362.

Pemoline (Cylert)

Mechanism of Action: Although it s mechanism of action is not known Pemoline is believed to be an amphetamine-like mild CNS stimulant. However, it has less peripheral sympathetic nervous system stimulating effects, therefore it produces fewer effects on the heart and blood pressure than does methylphenidate or amphetamine.

Therapeutic Use: Treatment of Attention Deficit Hyperactivity disorders (ADHD).

Absorption: Well absorbed in the GI tract. Peak effect 2-4 hours.

Metabolism: Metabolized in the liver and 50% is excreted unchanged by the kidneys.

Half-life: 12 Hours.

Average Daily Dose (adult): 50 to 75 mg.

Adverse Effects: Insomnia (disturbed sleep), dyskenisia (impairment of normal movement) of the face and extremities, depression, headache, nystagmus (involuntary rapid eye movement), dizziness and irritability. There have been reports of liver dysfunction ranging from mild hepatitis to complete liver failure.

Drug Interaction: The interaction of Cylert (Pemoline) with other drugs has not been studied in humans. Contraindication: Use with caution in impaired renal or liver function. Should not be used in patients with Tourette s Syndrome.

General References:

Elovic, E. (2000). Use of provigil for underarousal following tbi.Journal of Head Trauma Rehabilitation. 15(4), 1068-1071.

Hornstein, A., Lennihan, L., Seliger, G., Lichtmlan, S., & Shroeder, K. (1996). Amphetamine in recovery from brain injury. Brain Injury. 145-148.

Elovic, E. (1996). Pharmacology of attention and arousal in the low level patient. Neurorehabilitation, 6(1), 57-68.

Reinhard, D., Whyte, J., Sandel, E. (1996). Improved arousal and inititation following tricyclic antidepressant use in severe brain injury. Archives of Physical Medicine and Rehabilitation. 77(1), 80-83.

Kraus, M. (1995). Neuropsychiatric sequalae of stroke and traumatic brain injury: the role of psychostimulants. International Journal of Psychiatry in Medicine. 25(1), 39-51.

Gualtieri, C.T. & Evans, R.W. (1988). Stimulant treatment for the neurobehavioural sequelae of traumatic brain injury.Brain Injury. 2(4), 273-290.

Glenn, M.B. (1986). CNS stimulants: Applications for traumatic brain injury.Journal of Head Trauma Rehabilitation. 1(4), 74-76.