How to convert desmopressin (DDAVP) from subcutaneous (SC) to oral (PO) administration?

From the Guidelines

To convert desmopressin (DDAVP) from subcutaneous (SC) to oral (PO) administration, the recommended conversion ratio is approximately 1:10 to 1:20 due to the significantly lower bioavailability of oral desmopressin. For example, if a patient is receiving 2 micrograms of SC desmopressin, they would typically need 20-40 micrograms orally. The standard oral tablet strengths are 0.1 mg and 0.2 mg (100 and 200 micrograms) 1. When switching, start with the lower equivalent dose and titrate based on clinical response, monitoring for symptom control and fluid balance. Oral desmopressin should be taken at the same time each day, preferably at bedtime for patients with nocturnal polyuria or diabetes insipidus. Patients should limit fluid intake from 1 hour before until 8 hours after taking oral desmopressin to reduce the risk of hyponatremia. The conversion is necessary because oral desmopressin has only about 5-10% bioavailability compared to parenteral forms due to degradation in the gastrointestinal tract. Regular monitoring of serum sodium levels is essential when initiating therapy or changing routes of administration 1.

Some key points to consider when converting from SC to PO administration include:

• Starting with a lower equivalent dose and titrating based on clinical response
• Monitoring for symptom control and fluid balance
• Limiting fluid intake to reduce the risk of hyponatremia
• Regular monitoring of serum sodium levels
• Being aware of the potential for water intoxication, a rare but serious side effect of DDAVP 1

It's also important to note that the combination of DDAVP and a sustained-release anticholinergic agent may be more effective than DDAVP alone 1. However, more evidence is required to support this as a standard treatment for enuresis. Overall, the goal of converting from SC to PO administration is to achieve effective symptom control while minimizing the risk of adverse effects, and this can be achieved by following the recommended conversion ratio and monitoring guidelines.

From the FDA Drug Label

When switching from desmopressin acetate tablets to desmopressin acetate injection, titrate dose individually according to the diuresis (antidiuretic response) and electrolyte status (serum sodium) due to the large variability in both PK and PD.

When switching from desmopressin acetate injection to desmopressin acetate tablets is not directly addressed, however the inverse is mentioned: When switching from desmopressin acetate tablets to desmopressin acetate injection, titrate dose individually according to the diuresis (antidiuretic response) and electrolyte status (serum sodium) due to the large variability in both PK and PD.

The conversion from subcutaneous (SC) to oral (PO) administration of desmopressin (DDAVP) should be done by titrating the dose individually according to the diuresis (antidiuretic response) and electrolyte status (serum sodium) of the patient, due to the large variability in both pharmacokinetics (PK) and pharmacodynamics (PD) 2.

• Monitor patients closely during the initial dose titration period.
• Key considerations for conversion include:
  • Diuresis: monitor the patient's antidiuretic response.
  • Electrolyte status: monitor the patient's serum sodium levels.
  • Dose titration: adjust the dose based on the patient's response to treatment.

From the Research

Conversion from Subcutaneous to Oral Administration

To convert desmopressin (DDAVP) from subcutaneous (SC) to oral (PO) administration, the following points should be considered:

• The bioavailability of DDAVP after oral administration is approximately 0.1% compared to subcutaneous administration 3.
• A study found that the average oral DDAVP dose required to control diuresis was 19 times more than the prior intranasal treatment 4.
• The recommended oral dose of DDAVP is 100-300 micrograms, 2-3 times a day 5.
• A retrospective analysis found that the mean oral dosage of DDAVP was 417 micrograms, with a dosage ratio of about 20 compared to nasal administration 6.
• Oral DDAVP tablets have been used effectively in long-term treatment of central diabetes insipidus, with doses ranging from 400-600 micrograms/day in 2-3 administrations 7.

Key Considerations

• The oral dose of DDAVP may need to be significantly higher than the subcutaneous dose due to the low bioavailability of the oral formulation.
• The frequency of administration may also need to be adjusted, with oral doses typically given 2-3 times a day.
• Patients should be monitored closely to ensure that the oral dose is effective in controlling diuresis and that no adverse effects occur.
• The use of oral DDAVP may offer improved patient compliance and quality of life compared to subcutaneous or nasal administration.