Study of an Extended-Release, Crystalline Formulation of Recombinant Human Growth Hormone (ALTU-238) in Growth Hormone Deficient Adults to Determine Pharmacokinetics, Pharmacodynamics, and Drug Safety

Inclusion Criteria: * Growth hormone deficient men and women ages 18-60 years with a hypothalamic and/or pituitary structural lesion or longstanding idiopathic GHD * Growth hormone deficiency as determined by pituitary testing within the last five years by either of the two following tests: 1. Insulin hypoglycemia (glucose \< 50 mg/dL) with maximum GH \< 5 ng/mL (5 µg/L) by radioimmunoassay or \< 2.5 µg/L, if measured by immunoradiometric assay 2. Arginine-GHRH infusions with maximum GH \< 5 ng/mL (5 µg/L) or \< 2.5 µg/L, if measured by immunoradiometric assay * Women must be of non-child bearing potential (hysterectomy, tubal ligation, or IUD are acceptable) during the three months prior to entering the study, or post-menopausal (no menses for one year or more), or six to twelve months without menses and β-estradiol levels \< 20 pg/mL * Glucocorticoid use is allowed provided the subject has been on physiologic (\<7.5 mg prednisone or equivalent/day) replacement doses for at least 3 months * Free thyroxine (T4) within the normal range at Screening. If the subject is receiving thyroid hormone replacement therapy, the dose must be stable for at least 6 weeks prior to Screening * Willing and able to provide written informed consent * BMI 20 - 36 kg/m2 Exclusion Criteria: * Any previous or ongoing clinically significant illness that, in the opinion of the investigator, could prevent the subject from completing the study * Any history of cancer within the past 5 years, except for dermal squamous and basal cell carcinoma with documented 6-month remission. Subjects with a more recent history of successfully treated cervical carcinoma in situ will not be excluded provided there is documented 12-month remission * BMI \<20 or \>36 kg/m2 * Any allergic or abnormal reaction to human growth hormone * Inability of the subject to discontinue use of their regularly prescribed human growth hormone treatment from six weeks prior to Day -1 through the completion of the study * Serum creatinine \> 1.4 mg/dL * Hypocalcemia or hypercalcemia from any cause * Hyperparathyroidism, osteomalacia or any other disorder which may affect bone and bone markers including the use of bisphosphonates or other medications for osteoporosis * Participation in another clinical trial 30 days prior to screening * Demonstrated inability to comply with protocol requirements (e.g. uncooperative attitude, inability to return for follow-up visits, history of medical non-compliance, and/or poor likelihood of completing the study) * Blood donation within 56 days of the screening visit * Plasma donation within seven days of the screening visit * Positive serum pregnancy test * Women of child bearing potential * Abuse of alcohol; to be determined by principal investigator * Abuse of prescription or illicit drugs; to be determined by principal investigator