Pharmacogenomic Contributions to Trihexyphenidyl Biotransformation and Response in Children With Dystonic Cerebral Palsy

Cmax will be measured in first-dose pharmacokinetic study on study day 1

AUC0-n will be measured in first-dose pharmacokinetic study on study day 1

AUC0-∞ will be measured in first-dose pharmacokinetic study on study day 1

Measure percent of participants who were approached for the study that enrolled in the study

Measure percent of participants enrolled who completed the study

Measure percent of participants enrolled who were able to complete each dystonia efficacy measure (see secondary outcome measures)

Adverse events will only include those that are determined to be related to the study drug.

The Dyskinesia Impairment Scale, Version 2 (DIS-2) is an updated version of the Dyskinesia Impairment Scale used to assess dystonia across multiple body regions.

Duration of dystonia using subscale DIS-D are measured in 12 body regions during activity and rest.

Dystonia duration scores are measured on a 4-point scale from 0 to 4 with 0 being dystonia is absent and 4 being dystonia is always present (≥90%).

Amplitude of dystonia using subscale DIS-D are measured in 12 body regions during activity and rest.

Dystonia amplitude scores are measured on a 4-point scale from 0 to 4 with 0 being dystonia is absent and 4 being dystonia in maximal range of motion (≥90%).

Upper extremity function in 1 domain; grasp. 13 activities with item-level scores and three items for the tester to rate: hand function, spasticity, and cooperativeness. All scores are summed, and formulas are used to calculate percentages for this domain. Domain percentage is summed with a minimum score less than 0, and the maximum score is 100.

Functional impact scores are measured on a 5-point scale from 0 to 4 with 0 being dyskinesia may be present but has no impact on the named activity, and 4 being dyskinesia is present and prevents child from doing a named activity, even with help. An "NA" option indicates the activity is difficult but NOT due to dyskinesia.

Priority scores are measured on a 4-point scale from 1 to 4 with 1 being an activity is not a priority and 4 being an activity is highest priority.

Performance scores are measured on a 10-point scale with 1 being not able to do an activity at all and 10 being able to do an activity extremely well.

Satisfaction scores are measured on a 10-point scale with 1 being not satisfied at all with the way they do an activity to 10 being extremely satisfied with the way they do an activity.

Scores for each domain and for the total survey are standardized and range from 0 to 100 with 0 being the worst and 100 being the best.

Scores are measured on a 5-point scale from Completely Disagree to Completely Agree for items 1) The outcome measure meets my approval. 2) The outcome measure is appealing to me. 3) I like the outcome measure. 4) I welcome the outcome measure

The Patient Global Impression of Severity (PGI-S) is a single-item outcome measure assessing overall disease severity over the past week. Clinicians rate the participant's condition on a 5-point scale: none, mild, moderate, severe, or very severe. Higher scores indicate greater perceived severity.

The Patient Global Impression of Change (PGI-C) is a single-item outcome assessing overall change since the start of the study. Participants and the clinician rate the participant's condition on a 7-point Likert scale ranging from very much improved to very much worse.