The dosage for injection modecate (fluphenazine decanoate) can vary depending on the individual's condition and response to treatment. It is typically administered every 2 to 4 weeks, with the initial dose usually ranging from 12.5 to 25 mg. The dosage may be adjusted based on the patient's symptoms and tolerance to the medication. It is important to follow the recommendations of a healthcare provider when determining the appropriate dosage for injection modecate.