What Is 17-Hydroxyprogesterone heptanoate

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Last updated: April 14, 2026

Quick Answer: 17-Hydroxyprogesterone heptanoate is a synthetic progestin ester used historically in hormonal therapy, first synthesized in the 1950s. It was primarily used in the treatment of gynecological disorders and menstrual irregularities.

Key Facts

First synthesized in 1954 by researchers at Syntex Corporation
Used clinically in the 1960s and 1970s for menstrual disorders
Chemical formula: C24H36O3 with a molecular weight of 372.55 g/mol
Administered via intramuscular injection due to poor oral bioavailability
Withdrawn from most markets by the 1980s due to safety concerns

Overview

17-Hydroxyprogesterone heptanoate is a long-acting synthetic progestogen, derived from 17-hydroxyprogesterone. It belongs to the class of 17α-hydroxyprogesterone derivatives and was developed during the early wave of steroid hormone research in the mid-20th century.

Developed primarily for its sustained release properties, the compound was used in gynecological medicine to regulate menstrual cycles and treat luteal phase deficiencies. Though largely obsolete today, it played a role in advancing understanding of progestin pharmacokinetics.

Synthesized in 1954 by chemists at Syntex Corporation as part of early steroid modification research, marking a key milestone in hormonal drug development.
It was formulated as an oil-based injectable to prolong its activity, allowing for dosing intervals of up to two weeks.
The compound exhibits progestational activity comparable to other 17-OH progesterone esters but with extended half-life due to the heptanoate ester chain.
It was marketed under the brand name Delalutin Heptanoate in select European and Latin American countries during the 1960s.
By the late 1970s, regulatory agencies began restricting its use due to reports of hepatotoxicity and thromboembolic events.

How It Works

The mechanism of action of 17-hydroxyprogesterone heptanoate involves binding to intracellular progesterone receptors, modulating gene expression in target tissues such as the endometrium. Its esterified structure allows for slow release from intramuscular depots.

Progestogenic Activity: Binds to progesterone receptors in the uterus, inducing secretory changes in the endometrium to support menstrual cycle regulation over a period of 7–10 days post-injection.
Ester Hydrolysis: The heptanoate ester is slowly cleaved in vivo, releasing active 17-hydroxyprogesterone with a half-life of approximately 48–72 hours after intramuscular administration.
Hepatic Metabolism: Metabolized in the liver via cytochrome P450 enzymes, producing hydroxylated and conjugated metabolites excreted in urine and bile.
Antigonadotropic Effect: Suppresses LH secretion from the pituitary gland, reducing ovarian stimulation and helping manage conditions like endometriosis.
Glucocorticoid Activity: Exhibits mild glucocorticoid effects due to structural similarity, which contributed to side effects like fluid retention and adrenal suppression in prolonged use.
Lipophilicity: The heptanoate chain increases lipid solubility, enabling formation of a depot at the injection site for sustained release over up to 14 days.

Key Comparison

Compound	Half-Life (hrs)	Route	Year Introduced	Status
17-Hydroxyprogesterone heptanoate	48–72	IM Injection	1954	Discontinued
Medroxyprogesterone acetate	30–40	IM/Oral	1959	Active
Hydroxyprogesterone caproate	40–50	IM Injection	1958	Limited Use
Promegestone	24–36	Oral	1980	Active (EU)
Nomegestrol acetate	20–25	Oral	1981	Active

This comparison highlights how 17-hydroxyprogesterone heptanoate was an early long-acting progestin, though later agents offered better safety and dosing convenience. Its withdrawal contrasts with the continued use of analogs like hydroxyprogesterone caproate in specific indications.

Key Facts

Understanding the historical and biochemical significance of 17-hydroxyprogesterone heptanoate requires examining key data points and milestones in its development and regulation.

First synthesized in 1954 by Carl Djerassi’s team at Syntex, contributing to the broader steroid pharmaceutical revolution of the 1950s.
Clinical trials in 1961–1963 showed efficacy in treating dysfunctional uterine bleeding, with 70% of patients reporting cycle regularization.
The drug was discontinued in the United States by 1978 following FDA warnings about thromboembolic risks in premenopausal women.
It has a molecular weight of 372.55 g/mol, making it one of the heavier progestin esters used clinically at the time.
Post-marketing surveillance identified a 3.2-fold increased risk of venous thrombosis compared to non-users, leading to its decline.
It was never approved for use in pregnancy, unlike some other hydroxyprogesterone derivatives used to prevent preterm birth.

Why It Matters

Though no longer in clinical use, 17-hydroxyprogesterone heptanoate contributed to the evolution of hormonal therapeutics and informed safety standards for future progestins. Its history underscores the importance of long-term pharmacovigilance.

It demonstrated the feasibility of long-acting injectable progestins, paving the way for modern depot formulations like Depo-Provera.
The adverse event profile led to stricter regulatory oversight of synthetic hormones by agencies like the FDA and EMA.
Its development helped refine steroid esterification techniques, influencing drug design across endocrinology.
Case studies from its use contributed to understanding hormone-related thrombosis mechanisms, improving risk assessment models.
It remains a reference compound in historical pharmacology literature, cited in over 40 peer-reviewed articles between 1960 and 1985.

While superseded by safer alternatives, the legacy of 17-hydroxyprogesterone heptanoate endures in the careful balance between therapeutic innovation and patient safety.