What is the dosing regimen of oxybutynin (Ditropan)?

From the Guidelines

The recommended dosing regimen of oxybutynin is 5 mg at bedtime, which may need to be doubled as needed. This dosing is based on the study by 1, which evaluated the treatment for monosymptomatic enuresis and found oxybutynin to be effective in suppressing detrusor overactivity.

Key Considerations

• The dose may need to be adjusted based on the patient's response and tolerability, with a maximum daily dose not specified in the study.
• It is essential to consider non-pharmacological methods to decrease detrusor overactivity before initiating anticholinergic treatment, such as instituting sound, regular voiding habits.
• Patients should be monitored for potential side effects, including constipation, which may be heralded by a slowly decreasing anti-enuretic effect, and post-void residual urine, which may cause UTIs.

Important Details

• The study by 1 found that oxybutynin is useful in approximately 40% of children with enuresis who have failed standard treatment, and often combination treatment with desmopressin is needed.
• The anti-enuretic effect of oxybutynin should appear within a maximum of 2 months, and sometimes much earlier.
• Patients and their families should be aware of the potential risks, including mood changes, although this side effect seems to be uncommon when alternatives other than oxybutynin are chosen.

From the FDA Drug Label

The plasma concentration-time profiles for R- and S-oxybutynin are similar in shape; Figure 1 shows the profile for R-oxybutynin Table 1 Mean (SD) R-and S-Oxybutynin Pharmacokinetic Parameters Following Three Doses of 5 mg Oxybutynin Chloride. Administered every 8 Hours (n=23) Figure 2. Mean steady-state (±SD) R-oxybutynin plasma concentrations following administration of total daily oxybutynin chloride tablet dose of 7.5 mg to 15 mg (0.22 mg/kg to 0. 53 mg/kg) in children 5-15 years of age. The dosing regimen of oxybutynin (Ditropan) is 5 mg administered every 8 hours as shown in Table 1, and 5 mg twice daily or 5 mg three times daily as indicated by the normalization of data in Figure 2 and Table 2 for pediatric patients 2.

• Total daily dose for pediatric patients ranged from 7.5 mg to 15 mg.
• Most patients (86.9%) were taking a total daily oxybutynin chloride dose between 10 mg and 15 mg.

From the Research

Dosing Regimen of Oxybutynin (Ditropan)

The dosing regimen of oxybutynin (Ditropan) varies depending on the formulation and the individual patient's response to the medication.

• The immediate-release formulation is typically administered 2-3 times daily, with a dose range of 2.5-5 mg per administration 3, 4.
• The extended-release formulation can be administered once daily, with a dose range of 5-30 mg per day 5, 6, 7.
• A common dose for the extended-release formulation is 10 mg once daily, which has been shown to be effective and well-tolerated in clinical trials 6, 7.
• The dose of oxybutynin can be adjusted based on the patient's response to the medication, with some patients requiring higher or lower doses to achieve optimal efficacy and tolerability 3, 5, 7.

Flexible Dosing

Flexible dosing regimens have been used in clinical trials to optimize the efficacy and tolerability of oxybutynin.

• In one study, patients were started on a dose of 2.5 mg three times daily and could have their dose increased to 5 mg three times daily if they experienced little or no symptomatic relief and no side effects 3.
• In another study, patients were started on a dose of 5 mg once daily and could have their dose adjusted in 5 mg increments up to a maximum dose of 30 mg once daily 5.

Formulations

Oxybutynin is available in several formulations, including immediate-release and extended-release tablets.

• The extended-release formulation has been shown to have a smoother plasma concentration-time profile and a lower maximum plasma concentration than the immediate-release formulation, which may improve tolerability 7.
• The extended-release formulation can be administered once daily, which may improve patient compliance compared to the immediate-release formulation, which must be administered 2-3 times daily 4, 7.