This is an open-label dose-titration study in Japanese Central Diabetes Insipidus (CDI) patients designed to demonstrate the efficacy and safety of orally-disintegrating tablet of desmopressin.

Inclusion Criteria:

• Participants must be documented to have Central Diabetes Insipidus (CDI) by at least two of the following four criteria (a-d):

  1. Failure to increase urine osmolality above 300 mOsm/kg during a period of fluid deprivation sufficient to raise plasma osmolality and sodium above the upper limit of normal level for the reference laboratory (usually 295 mOsm/kg and 148 mEq/l, respectively)
  2. Complete and continuous control of the DI by desmopressin therapy without "breakthrough" diuresis, hypernatremia, hyponatremia, or symptoms or signs of water intoxication.
  3. A deficient plasma vasopressin response to osmotic or non-osmotic stimulation.
  4. Absence of the posterior pituitary bright spot on T-1 weighted midsagittal magnetic resonance imaging (MRI) of the brain.

• Given written informed consent prior to any trial-related procedure is performed

• 24 hour urine volume (mL), urine osmolality (mOsm/kg), urine specific gravity, and serum sodium (mEq/L) maintained at a normal level by desmopressin nasal administration

• Outpatient

• The participant is, in the investigator's opinion, otherwise healthy

• Be willing and able to comply with the protocol requirements including restriction of water intake

Exclusion Criteria:

• Presence or a history of nephrogenic diabetes insipidus or diabetes mellitus
• Presence of uncorrected hypothyroidism, hypoadrenalism or hypogonadism
• Abnormalities or disease of the oral cavity that might affect the release and absorption of drug
• Unable to be placed on water-intake restriction starting from two hours before bedtime
• Presence of a hypothalamus abnormality leading to thirst disorder
• Evidence of hepatic, renal, cardiac, or pulmonary dysfunction
• Uncontrolled hypertension
• Treatment with another investigational product within the past 3 months
• Concurrent treatment with diuretics, chlorpropamide, tricyclic antidepressants, indomethacin, carbamazepine
• Alcohol dependency or drug abuse
• Breastfeeding, pregnant, or likely to become pregnant
• A mental condition, the lack of decision-making ability, dementia or a speech handicap
• Any other reason that the Investigator believes inappropriate