Oxybutynin

Inquiry

Cat Number

API0232177

CAS Number

5633-20-5

For research use only. We do not supply to patients.

For pharmaceutical-grade products or other inquiries, please contact our experts.

Product Detail Description Scientific Support Advanced Innovations Customer Q&A

CAS Number

5633-20-5

EINECS

630-332-7

Storage

Store at room temperature

Synonyms

Oxytrol; Oxybutynine; kentera; Oxibutinina; Oxybutyninum; Anturol; Cystrin; 4-Diethylamino-2-butinyl alpha-cyclohexylmandelat

Molecular Formula

C22H31NO3

Molecular Weight

357.5

Smiles

CCN(CC)CC#CCOC(=O)C(C1CCCCC1)(C2=CC=CC=C2)O

Appearance

White to off-white solid

Melting Point

125-130°C

Boiling Point

494.4±45.0°C at 760 mmHg

Relative Density

1.1±0.1

General Description

Oxybutynin is an antispasmodic, anticholinergic agent with a tertiary amine structure, a cyclohexylphenyl glycolate ester. It exists as a racemic mixture of R- and S-enantiomers. The molecule contains a phenyl group and a cyclohexyl group attached to a glycolic acid backbone, with a dimethylaminoethyl side chain.

Mechanism of Action

Oxybutynin acts as a competitive antagonist at muscarinic acetylcholine receptors (M1, M2, M3 subtypes) in the bladder detrusor muscle, reducing involuntary bladder contractions. It also exerts a direct papaverine-like spasmolytic action on smooth muscle, independent of cholinergic blockade, which contributes to its efficacy. Its active metabolite, N-desethyloxybutynin, is responsible for most of the anticholinergic effects.

Application

Oxybutynin is indicated for the treatment of overactive bladder (OAB), including symptoms of urge incontinence, urgency, and urinary frequency, as well as for neurogenic detrusor overactivity in children. It is also used for the management of hyperhidrosis (excessive sweating). Its tertiary amine structure allows CNS penetration, leading to central anticholinergic side effects, unlike quaternary ammonium anticholinergics.

In a first-in-human study, eight healthy women received a single 3 mg intravaginal dose of oxybutynin hydrochloride via the microprocessor-controlled MedRing device. Plasma levels of oxybutynin and its active metabolite N-desethyloxybutynin were comparable to oral administration, with Cmax 5.4 ± 2.7 ng/mL and AUCinf 34.9 ± 17.4 h·ng/mL. No serious adverse events occurred. The MedRing device effectively delivered oxybutynin intravaginally with good tolerability.

Fig. 1 Individual pharmacokinetic profiles of oxybutynin (A) and N-desethyloxybutynin (B) up to 22 h after intravaginal dosing with 3 mg oxybutynin hydrochloride. (de Laat W, et al., 2023)

References

de Laat W, et al. First-in-human study to assess the pharmacokinetics, tolerability, and safety of single-dose oxybutynin hydrochloride administered via a microprocessor-controlled intravaginal ring. Drug Deliv. 2023;30(1):2180113.

In a double‑blind crossover trial, 11 children with Down syndrome and obstructive sleep apnea (baseline OAHI 7.4) received low‑dose (0.5 mg/kg atomoxetine + 5 mg oxybutynin) and high‑dose (1.2 mg/kg + 5 mg) regimens. Both significantly reduced OAHI to 3.6 and 3.9, respectively (P≤0.003). Sleep architecture was unchanged. OSA‑18 scores showed nonsignificant improvement. Mild irritability and fatigue were common. Atomoxetine‑oxybutynin is a promising treatment for OSA in children with Down syndrome.

Fig. 2 Participant-level changes in obstructive AHI (events/h) with low-dose and high-dose ato-oxy. (Combs D, et al., 2023)

References

Combs D, et al. The combination of atomoxetine and oxybutynin for the treatment of obstructive sleep apnea in children with Down syndrome. J Clin Sleep Med. 2023;19(12):2065-2073.

Does Oxybutynin (free base) require protection from light and heat during storage?

Yes, it is photosensitive and thermally labile. Light causes photodegradation and heat accelerates hydrolysis of the ester group. Store in light-resistant containers at controlled room temperature (15-25°C).

Is Oxybutynin stable in solution for transdermal and oral formulations?

Formulated solutions are stable when protected from light and stored at room temperature.

What is the recommended packaging for Oxybutynin to prevent degradation?

Use amber glass or aluminum containers with tight closures, filled to minimize headspace. Avoid plastic containers that may absorb the API.

How is the impurity phenylcyclohexylglycolic acid (a hydrolysis product) monitored?

This degradation product is quantified using a stability-indicating HPLC method, ensuring it remains below pharmacopoeial limits.