Theophylline for Treatment of Pseudohypoparathyroidism

Pseudohypoparathyroidism is a genetic disorder with limited treatment options, characterized by early-onset obesity, short stature, hormone resistance and cognitive impairment. This phase 2 clinical trial will test the efficacy of theophylline, a phosphodiesterase inhibitor, in pseudohypoparathyroidism. We hypothesize that theophylline will cause weight loss, improve glucose tolerance and decrease hormone resistance in children and young adults.

Inclusion Criteria: * 1\. Successful completion of the randomized clinical trial "Phase 2 Study of Theophylline Treatment of Pseudohypoparathyroidism IND 133103 (11/1/2016)". Exclusion Criteria: 1. History of a seizure disorder unrelated to hypocalcemia 2. History of a cardiac arrhythmia (not including bradycardia) 3. Hepatic insufficiency including cirrhosis and acute hepatitis (AST or ALT \>3x upper limit of normal) 4. Congestive heart failure 5. Current cigarette use or alcohol abuse 6. Pregnancy or intention to become pregnant during the next year 7. Active peptic ulcer disease 8. Current use of medications known to effect theophylline levels 9. History of hypersensitivity to theophylline or other medication components 10. Unable to comply with study procedures in the opinion of the investigator