A Phase 3, Open-label, Multicentre Study to Provide Access to Guanfacine Hydrochloride Extended Release for European Subjects with Attention-deficit/Hyperactivity Disorder (ADHD) who Participated in Study SPD503-315 or SPD503-316

For subjects enrolling from antecedent Study SPD503-315:;Subjects will be eligible if they met the response criteria for entry into Phase 2, were;randomized, and completed Phase 2 or withdrew early because the protocol-defined treatment;failure criteria was met.;For subjects enrolling from antecedent Study SPD503-316:;Children age 6-12, regardless of treatment group, must complete 10 weeks of double-blind;treatment, reach Visit 15/Final, and complete the 2-week dose taper.;Adolescents age 13 and older, regardless of treatment group, must complete 13 weeks of;double-blind treatment, reach Visit 15/Final, and complete the 2-week dose taper.;For all subjects:;1. For subjects where Study SPD503-318 was not available at the time of subject*s;final visit in the antecedent study (SPD503-315 or SPD503-316), subject may still;screen unless they are well-controlled on another ADHD medication with;acceptable tolerability and the parent/caregiver is satisfied with the current ADHD;medication.;2. Subject satisfied all entry criteria for the antecedent study (SPD503-315 or;SPD503-316).;3. Subject who is a female of child-bearing potential (FOCP), defined as >9 years of;age or <9 years of age and is post-menarchal, must have a negative serum beta;Human Chorionic Gonadotropin (*-hCG) pregnancy test at the Screening Visit;(Visit 1) and a negative urine pregnancy test at the Baseline Visit (Visit 2) and;agree to comply with any applicable contraceptive requirements of the protocol.;4. Subject*s parent or legally authorised representative (LAR) must provide signature;of informed consent, and there must be documentation of assent (if applicable) by;the subject indicating that the subject is aware of the investigational nature of the;study and the required procedures and restrictions in accordance with the;International Conference on Harmonisation (ICH) Good Clinical Practice (GCP);Guideline E6 and applicable regulations, before completing any study-related;procedures.;5. Subject and parent/LAR are willing, able, and likely to fully comply with all the;testing and requirements defined in this protocol, including oversight of dosing.;Specifically, the parent/LAR must be available upon awakening, to dispense the;dose of investigational product for the duration of the study.;6. Subject has a supine and standing blood pressure (BP) measurement within the;95th percentile for age, sex, and height.;7. Subject is functioning at an age-appropriate level intellectually, as deemed by the;Investigator.;8. Subject is able to swallow intact tablets.

1. Subject has any current, controlled (requiring a prohibited medication or behavioural;modification program) or uncontrolled, co-morbid psychiatric diagnosis [except;oppositional defiant disorder (ODD)], including any severe comorbid Axis II disorders;or severe Axis I disorders such as post traumatic stress disorder (PTSD), bipolar;illness, psychosis, pervasive developmental disorder, obsessive-compulsive disorder;(OCD), substance abuse disorder, or other symptomatic manifestations or lifetime;history of bipolar illness, psychosis or conduct disorder that, in the opinion of the;Investigator, contraindicate treatment with SPD503 or confound efficacy or safety;assessments. Review the Kiddie Schedule for Affective Disorders and Schizophrenia *;Present and Lifetime version (K-SADS-PL) from the antecedent study to confirm;diagnosis, if necessary.;2. Subject who early terminated from Study SPD503-315 or Study SPD503-316 for;protocol non-adherence, subject non-compliance, an adverse event (AE), serious;adverse event (SAE), or withdrawal by subject.;3. Subject experienced any clinically significant AE in a prior SPD503 study (SPD503-;315 or SPD503-316) that, in the opinion of the Investigator, would preclude exposure;to SPD503.;4. Clinically important abnormality on urine drug and/or alcohol screen at the Screening;Visit (Visit 1).;5. Subject has taken any investigational medicinal product as follows: last dose of;investigational product in Study SPD503-315 within 7 days prior to the Baseline Visit;(Visit 2); investigational product in Study SPD503-316 within 30 days prior to the;Baseline Visit (Visit 2); any other investigational product within 30 days prior to the;Baseline Visit (Visit 2) or any other ADHD medication within 30 days prior to;Baseline Visit (Visit 2).;6. Subject is significantly overweight based on Center for Disease Control and;Prevention Body Mass Index (BMI)-for-age sex-specific charts at the Screening Visit;(Visit 1). Significantly overweight is defined as a BMI >95th percentile.;7. Children aged 6 to 12 years with a body weight of less than 25.0kg or adolescents;aged 13 years and older with a body weight of less than 34.0kg at the Screening Visit;(Visit 1).;8. Subject has any condition or illness including clinically significant abnormal;laboratory values at the Screening Visit (Visit 1) which, in the opinion of the;Investigator, represents an inappropriate risk to the subject and/or could confound the;interpretation of the study.;9. Subject is currently considered a suicide risk in the opinion of the Investigator, has;previously made a suicide attempt, or has a prior history of, or is currently;demonstrating active suicidal ideation. Subjects with intermittent passive suicidal;ideation are not necessarily excluded based on the assessment of the Investigator.;10. Subject has clinically significant ECG findings, as judged by the Investigator with;consideration of the central ECG laboratory*s interpretation, at the Baseline Visit;(Visit 2).;11. Subject has a known or suspected allergy, hypersensitivity, or clinically significant;intolerance to guanfacine hydrochloride, or any components found in SPD503.;12. Subject has a history of alcohol or other substance abuse or dependence, as defined by;DSM-IV-TR (with the exception of nicotine) within the last 6 months.;13. Subject has a history of a seizure disorder (other than a single childhood febrile;seizure occurring before the age of 3 years) or the presence of a serious tic disorder;including Tourette*s syndrome.;14. Subject has a known history or presence of structural cardiac abnormalities, serious;heart rhythm abnormalities, syncope, cardiac conduction problems (e.g., clinically;significant heart block), exercise-related cardiac events including syncope and pre;syncope, or clinically significant bradycardia.;15. Subject with orthostatic hypotension or a known history of controlled or uncontrolled;hypertension.;16. Current use of any prohibited medication or other medications, including herbal;supplements, that affect BP or heart rate or that have CNS effects or affect cognitive;performance, such as sedating antihistamines and decongestant sympathomimetics;(inhaled bronchodilators are permitted) or a history of chronic use of sedating;medications [i.e., antihistamines]) in violation of the protocol specified washout;criteria at the Baseline Visit (Visit 2).;17. Subject has a medical condition, other than ADHD, that requires treatment with;medications that have central nervous system effects and/or affect performance.;18. Subject is female and is pregnant or currently lactating.;19. Subject failed screening or was previously enrolled in this study.