Alizin Injection for Dogs (Aglepristone 30mg/ml) – Pregnancy Termination & Pyometra Treatment | 10ml

Alizin for Dogs – Aglepristone 30mg/ml Solution for Injection

Alizin is a veterinary injectable medication manufactured by Virbac, containing aglepristone 30mg/ml, a synthetic progesterone antagonist. It is primarily licensed for the safe termination of unwanted pregnancy (misalliance) in bitches up to 45 days after mating. Alizin works by blocking progesterone receptors in the uterus, preventing implantation and maintenance of pregnancy, leading to abortion or fetal resorption.

While licensed for dogs, Alizin is also used off-label under veterinary direction in cats for pregnancy termination and certain medical conditions including pyometra and mammary hyperplasia.

Composition

Alizin is provided as a clear, yellow, oily solution for injection in 10ml glass vials.

• Active substance: Aglepristone 30mg per 1ml
• Excipients: Ethanol (anhydrous) 0.1ml per 1ml, Arachis Oil (refined peanut oil) q.s. to 1ml

This product does not contain an antimicrobial preservative.

How Alizin Works – Mechanism of Action

Progesterone Antagonism: Aglepristone competitively binds to progesterone receptors in the uterus with an affinity 3 times higher than natural progesterone in dogs (9 times higher in cats). By blocking these receptors, it inhibits the effects of progesterone essential for embryo implantation and pregnancy maintenance, resulting in abortion or fetal resorption within approximately 7 days.

Hormonal Effects: Within 24 hours of administration, aglepristone does not significantly alter plasma concentrations of progesterone, prostaglandins, oxytocin, or cortisol. However, it induces a release of prolactin within 12 hours.

Anti-Glucocorticoid Effect: Aglepristone also binds to glucocorticoid receptors with affinity similar to dexamethasone but acts as an antagonist, potentially reducing the effects of corticosteroid treatments.

Pharmacokinetics: After subcutaneous injection (two doses of 10mg/kg, 24 hours apart), maximum plasma concentration (~280 ng/ml) is reached after approximately 2.5 days. Aglepristone is metabolised in the liver and excreted primarily via feces (~90%), with about 60% eliminated in the first 10 days and 80% over 24 days. Mean residence time is approximately 6 days.

Indications for Use

Dogs (Licensed Use):

• Induction of abortion in pregnant bitches up to 45 days after mating

Dogs (Off-Label Use):

• Medical treatment of pyometra (uterine infection), often combined with antibiotics and prostaglandins
• Induction of parturition (labour)

Cats (Off-Label Use):

• Termination of pregnancy (efficacy ~87% at day 25, ~67% at day 45)
• Medical treatment of pyometra
• Treatment of benign mammary hyperplasia (fibroadenomatous hyperplasia – FAH)

Off-label use should only occur under strict veterinary guidance.

Dosage and Administration

Administer by subcutaneous injection only, preferably in the scruff of the neck. Lightly massage the injection site after administration. Use strict aseptic technique.

Dogs (Pregnancy Termination):

• 10mg aglepristone per kg body weight (equivalent to 0.33ml Alizin per kg)
• Administer TWO injections, precisely 24 hours apart
• If dose volume exceeds 5ml, divide across two or more injection sites

Cats (Pregnancy Termination – Off-Label):

• 10–15 mg/kg body weight (0.33–0.5 ml/kg)
• TWO injections, 24 hours apart, as determined by the veterinarian

Pyometra Treatment (Off-Label):

• Dogs: 10mg/kg on Days 1, 2, 8 ± Day 15, combined with antibiotics
• Cats: 15mg/kg on Days 0, 2, 5, 8
• Requires intensive veterinary supervision and monitoring

Alizin Dosage Chart by Dog Weight

Note: Each injection is given once per day for 2 consecutive days. For doses exceeding 5ml, split across multiple injection sites.

Pyometra Treatment with Alizin (Off-Label)

Alizin is sometimes used as part of a medical management protocol for pyometra, particularly in breeding animals or those considered poor surgical candidates.

• Mechanism: Blocking progesterone leads to cervical relaxation and increased uterine contractility, facilitating expulsion of uterine contents
• Suitability: Best for open-cervix pyometra in systemically stable animals. Not recommended for closed-cervix pyometra or severely ill animals
• Monitoring: Ultrasound examinations and blood work are crucial during treatment
• Risks: Treatment failure, incomplete uterine emptying, recurrence in future cycles
• Note: Ovariohysterectomy (spay surgery) remains the definitive treatment for pyometra

Side Effects

• Injection site reactions (common): Pain (~17% of dogs), local inflammation (~23%). Usually resolve within 28 days
• Systemic effects: Anorexia (~25%), excitation/restlessness (~23%), depression (~21%), diarrhoea (~13%), vomiting (~2%)
• Post-abortion effects (after day 20): Fetal expulsion, vaginal discharge, reduced appetite, mammary congestion
• Uterine infections: Reported in 3.4% of dogs in field trials
• Early return to oestrus: Heat interval shortened by 1–3 months
• Cats: Haemorrhagic vaginal discharge has been specifically reported

Contact your veterinarian if purulent or haemorrhagic discharge persists over 3 weeks, or if your animal shows prolonged illness.

Contraindications

• Known hypersensitivity to aglepristone or excipients (especially peanut oil)
• Impaired liver or kidney function
• Diabetic animals
• Dogs in poor general health
• Addison’s disease or predisposition to hypoadrenocorticism
• Do not administer after 45 days post mating

Important Safety Warnings

• Treatment failure: Partial abortion seen in ~5% of bitches. Confirmation via ultrasound 10 days after treatment is essential
• Human safety: Aglepristone can induce abortion in humans. Pregnant women or women of childbearing age must wear protective gloves. In case of accidental self-injection, seek urgent medical advice immediately
• Drug interactions: Potential interactions with ketoconazole, itraconazole, and erythromycin. May reduce effectiveness of corticosteroids. Do not mix with other injectables

Storage

Store below 25°C. Protect from light. Shelf life after first opening: 28 days. Keep out of reach of children.

Frequently Asked Questions

How much Alizin does my dog need?
The dose is 0.33ml per kg of body weight, given as two subcutaneous injections exactly 24 hours apart. For example, a 10kg (22lb) dog needs 3.3ml per injection. See the dosage chart above for your dog’s weight.

How soon does Alizin work?
The abortion or fetal resorption process typically begins within a few days and is complete within 7 days of administration. A veterinary follow-up with ultrasound is recommended 10 days after treatment to confirm termination.

Can Alizin be used for pyometra?
Yes, Alizin is used off-label for the medical treatment of open-cervix pyometra in dogs and cats, usually combined with antibiotics. This should only be done under intensive veterinary supervision. Spay surgery remains the gold-standard treatment.

Is Alizin safe for cats?
Alizin is used off-label in cats for pregnancy termination and pyometra treatment at a dose of 10–15mg/kg. Its binding affinity in cats is 9 times higher than progesterone. Always consult a veterinarian.

What are the most common side effects?
The most commonly reported effects include injection site pain and swelling, temporary loss of appetite, restlessness, and mild depression. These are usually transient and resolve on their own.

Can I use Alizin after 45 days?
No. Alizin is only authorised for use up to 45 days post mating. After this point, the risks increase significantly and alternative options should be discussed with your veterinarian.

How many vials do I need for my dog?
Each vial contains 10ml. A 10kg dog needs 3.3ml per injection (6.6ml total for both injections) — so one vial is sufficient. A 30kg dog needs 9.9ml per injection (19.8ml total) — so two vials are required. Consult the dosage chart above.

Is Alizin available in the USA?
Alizin is manufactured by Virbac and is available in many countries. Availability may vary by region. We ship worldwide from our online store.

What is the efficacy rate?
In the first trimester (up to day 21), efficacy is approximately 99%. In the second trimester, efficacy is approximately 95%. In case of partial or failed abortion, repeat treatment may be given between days 30–45.