Syntocinon (Oxytocin) - Description and Clinical Pharmacology

Syntocinon^®

(oxytocin) injection, USP

Caution: Federal law prohibits dispensing without prescription.

DESCRIPTION

Syntocinon^® (oxytocin) is a synthetic, (1-6) cyclic nonapeptide. Chemically, oxytocin is designated as Glycinamide, L-cysteinyl-L-tyrosyl-L-isoleucyl-L-glutaminyl-L-asparaginyl-L-cysteinyl-L-prolyl- L-leucy1-, cyclic (1-6)-disulfide.

The structural formula is:

Syntocinon^® (oxytocin) injection is provided as a sterile solution for intravenous or intramuscular administration. Each 1 mL of solution contains 10 USP or International Units of oxytocin and the following inactive ingredients:

acetic acid, NF, qs to....................... pH 4 ± 0.3

alcohol, USP............................ 0.61 % by vol.

chlorobutanol, NF..........,................... 0.5%

sodium acetate, USP...,........................ 1 mg

sodium chloride, USP........................ 0.017 mg

water for injection, USP, qs to..................... 1 mL

CLINICAL PHARMACOLOGY

The pharmacologic and clinical properties of Syntocinon^® (oxytocin) are identical with the naturally occurring oxytocic principle of the posterior lobe of the pituitary. Syntocinon^® (oxytocin) injection does not contain the amino acids characteristic of vasopressin, and therefore has fewer and less severe cardiovascular effects. Syntocinon^® (oxytocin) exerts a selective action on the smooth musculature of the uterus, particularly toward the end of pregnancy, during labor and immediately following delivery. Oxytocin stimulates rhythmic contractions of the uterus, increases the frequency of existing contractions, and raises the tone of the uterine musculature.

Syntocinon^® (oxytocin), when given in appropriate doses during pregnancy, is capable of eliciting graded increases in uterine motility from a moderate increase in the rate and force of spontaneous motor activity to sustained tetanic contraction.

Syntocinon^® (oxytocin) is promptly effective after parenteral administration. Following intramuscular injection, the myotonic effect on the uterus appears in 3-7 minutes, and persists for 30-60 minutes. With intravenous injection, the uterine effect appears within 1 minute and is of more brief duration.