Pregnancy Category B. There are no adequate and well-controlled studies using oxybutynin chloride extended-release tablets in pregnant women. Oxybutynin chloride extended-release tablets should be used during pregnancy only if the potential benefit to the patient outweighs the risk to the patient and fetus. Women who become pregnant during oxybutynin chloride extended-release tablets treatment are encouraged to contact their physician.
Risk Summary
Based on animal data, oxybutynin is predicted to have a low probability of increasing the risk of adverse developmental effects above background risk.
Animal Data
Reproduction studies with oxybutynin chloride in the mouse, rat, hamster, and rabbit showed no evidence of impaired fertility or harm to the animal fetus.
Absorption
Following the first dose of oxybutynin chloride extended-release tablets oxybutynin plasma concentrations rise for 4 to 6 hours; thereafter steady concentrations are maintained for up to 24 hours, minimizing fluctuations between peak and trough concentrations associated with oxybutynin.
The relative bioavailabilities of R- and S-oxybutynin from oxybutynin chloride extended-release tablets are 156% and 187%, respectively, compared with oxybutynin. The mean pharmacokinetic parameters for R- and S-oxybutynin are summarized in Table 2. The plasma concentration-time profiles for R- and S-oxybutynin are similar in shape; Figure 1 shows the profile for R-oxybutynin.
Table 2: Mean (SD) R- and S-Oxybutynin Pharmacokinetic Parameters Following a Single Dose of Oxybutynin Chloride Extended-Release Tablets 10 mg (n=43)| Parameters (units) | R-Oxybutynin | S-Oxybutynin |
|---|
| C
max (ng/mL)
| 1.0 | (0.6) | 1.8 | (1.0) |
| T
max (h)
| 12.7 | (5.4) | 11.8 | (5.3) |
| t
1/2 (h)
| 13.2 | (6.2) | 12.4 | (6.1) |
| AUC
(0–48) (ng∙h/mL)
| 18.4 | (10.3) | 34.2 | (16.9) |
| AUC
inf (ng∙h/mL)
| 21.3 | (12.2) | 39.5 | (21.2) |
Figure 1: Mean R-oxybutynin plasma concentrations following a single dose of oxybutynin chloride extended-release tablets 10 mg and oxybutynin 5 mg administered every 8 hours (n=23 for each treatment).
Figure 1 (Oxybutynin Fig 1)
Steady state oxybutynin plasma concentrations are achieved by Day 3 of repeated oxybutynin chloride extended-release tablets dosing, with no observed drug accumulation or change in oxybutynin and desethyloxybutynin pharmacokinetic parameters.
Oxybutynin chloride extended-release tablets steady state pharmacokinetics were studied in 19 children aged 5 to 15 years with detrusor overactivity associated with a neurological condition (e.g., spina bifida). The children were on oxybutynin chloride extended-release tablets total daily dose ranging from 5 to 20 mg (0.10 to 0.77 mg/kg). Sparse sampling technique was used to obtain serum samples. When all available data are normalized to an equivalent of 5 mg per day of oxybutynin chloride extended-release tablets, the mean pharmacokinetic parameters derived for R- and S-oxybutynin and R- and S-desethyloxybutynin are summarized in Table 3. The plasma-time concentration profiles for R- and S-oxybutynin are similar in shape; Figure 2 shows the profile for R-oxybutynin when all available data are normalized to an equivalent of 5 mg per day.
Table 3: Mean ± SD R- and S-Oxybutynin and R- and S-Desethyloxybutynin Pharmacokinetic Parameters in Children Aged 5 to 15 Following Administration of 5 to 20 mg Oxybutynin Chloride Extended-Release Tablets Once Daily (n=19), All Available Data Normalized to an Equivalent of Oxybutynin Chloride Extended-Release Tablets 5 mg Once Daily | R-Oxybutynin | S-Oxybutynin | R- Desethyloxybutynin | S- Desethyloxybutynin |
|---|
| C
max (ng/mL)
| 0.7 ± 0.4 | 1.3 ± 0.8 | 7.8 ± 3.7 | 4.2 ± 2.3 |
| T
max (h)
| 5.0 | 5.0 | 5.0 | 5.0 |
| AUC (ng∙h/mL) | 12.8 ± 7.0 | 23.7 ± 14.4 | 125.1 ± 66.7 | 73.6 ± 47.7 |
Figure 2: Mean steady state (± SD) R-oxybutynin plasma concentrations following administration of 5 to 20 mg oxybutynin chloride extended-release tablets once daily in children aged 5 to 15. Plot represents all available data normalized to an equivalent of oxybutynin chloride extended-release tablets 5 mg once daily.
Figure 2 (Oxybutynin Fig 2)
Food Effects
The rate and extent of absorption and metabolism of oxybutynin are similar under fed and fasted conditions.
Distribution
Oxybutynin is widely distributed in body tissues following systemic absorption. The volume of distribution is 193 L after intravenous administration of 5 mg oxybutynin chloride. Both enantiomers of oxybutynin are highly bound (>99%) to plasma proteins. Both enantiomers of N-desethyloxybutynin are also highly bound (>97%) to plasma proteins. The major binding protein is alpha-1 acid glycoprotein.
Metabolism
Oxybutynin is metabolized primarily by the cytochrome P450 enzyme systems, particularly CYP3A4 found mostly in the liver and gut wall. Its metabolic products include phenylcyclohexylglycolic acid, which is pharmacologically inactive, and desethyloxybutynin, which is pharmacologically active. Following oxybutynin chloride extended-release tablets administration, plasma concentrations of R- and S-desethyloxybutynin are 73% and 92%, respectively, of concentrations observed with oxybutynin.
Excretion
Oxybutynin is extensively metabolized by the liver, with less than 0.1% of the administered dose excreted unchanged in the urine. Also, less than 0.1% of the administered dose is excreted as the metabolite desethyloxybutynin.
Dose Proportionality
Pharmacokinetic parameters of oxybutynin and desethyloxybutynin (C
max and AUC) following administration of 5 to 20 mg of oxybutynin chloride extended-release tablets are dose proportional.
Use in Specific Populations
Pediatric
The pharmacokinetics of oxybutynin chloride extended-release tablets were evaluated in 19 children aged 5 to 15 years with detrusor overactivity associated with a neurological condition (e.g., spina bifida). The pharmacokinetics of oxybutynin chloride extended-release tablets in these pediatric patients were consistent with those reported for adults (see
Tables 2 and
3, and
Figures 1 and
2 above).
Gender
There are no significant differences in the pharmacokinetics of oxybutynin in healthy male and female volunteers following administration of oxybutynin chloride extended-release tablets.
Race
Available data suggest that there are no significant differences in the pharmacokinetics of oxybutynin based on race in healthy volunteers following administration of oxybutynin chloride extended-release tablets.
For more information, go to www.accordhealthcare.us or call Accord Healthcare Inc. at 1-866-941-7875.
Manufactured For:
Accord Healthcare, Inc.,
1009 Slater Road,
Suite 210-B,
Durham, NC 27703,
USA.
Manufactured By:
Intas Pharmaceuticals Limited,
Plot No. : 457, 458,
Village – Matoda,
Bavla Road, Ta.- Sanand,
Dist.- Ahmedabad – 382 210,
INDIA.
10 1091 1 697321
Issued May 2019