POM-V Prescription Required

Mamyzin 269.5mg/ml Powder and Solvent for Suspension for Injection for Cattle

Active ingredients: Penethamate Hydriodide, micronised

Form

Injection

Species

Cattle

Manufacturer

Boehringer Ingelheim Animal Health UK Limited

VMD MA No.

08327/5056

What it's used for

Bovine mastitis caused by penicillin sensitive organisms.

Full indications, dosage and side effects ↓

View official SPC (PDF)

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Clinical information

Mamyzin 269.5mg/ml Powder and Solvent for Suspension for Injection for Cattle — SPC Details

Source: VMD Summary of Product Characteristics (SPC). Last updated 26 Mar 2026.

Bovine mastitis caused by penicillin sensitive organisms.

Reconstitution:
5g vial with the 15ml vial of diluent OR the 10g vial with the 30 ml vial of diluent
provided.
Use only 5g vial with 15ml diluent and 10g vial with 30ml diluent to
provide the correct dose.
Shake well after reconstitution.
Dosage: The daily dose is 15 mg penethamate hydriodide per kg bodyweight
for 3 consecutive days. This is equivalent to 5.5 ml of the reconstituted
suspension per 100 kg bodyweight.
Shake well before administration.
For intramuscular use. Do not administer intravenously.
To ensure a correct dosage, bodyweight should be determined as accurately as
possible to avoid under-dosing.

Do not use in animals known to be hypersensitive to penicillin.
Do not administer by intravenous injection.

In very rare cases anaphylactic shock may occur, which can be fatal.

None.

Revised: August 2025
MA split from NI MA following AN: 01377/2025

Special precautions for use in animals
Use of the product should be based on susceptibility testing of the bacteria
isolated from the animal. If this is not possible, therapy should be based on
local (regional, farm level) epidemiological information about susceptibility of
the target bacteria.
Official, national and regional antimicrobial policies should be taken into
account when the product is used.
Use of the product deviating from the instructions given in the SPC may
increase the prevalence of bacteria resistant to benzylpenicillin and may
decrease the effectiveness of treatment with other beta-lactams due to the
potential for cross-resistance.
Special Precautions to be taken by the person administering the medicinal
product to animals
Penicillins and cephalosporins may cause hypersensitivity (allergy) following
injection, inhalation, ingestion or skin contact. Hypersensitivity to penicillins may
lead to cross-reactions to cephalosporins and vice versa. Allergic reactions to
these substances may occasionally be serious.
1. Do not handle this product is you know you are sensitised, or if you have
been advised not to work with such preparations.
2. Handle the product with great care to avoid exposure, taking all
recommended precautions.
3. If you develop symptoms following exposure such as a skin rash, you
should seek medical advice and show the Doctor this warning. Swelling of
the face, lips or eyes or difficulty breathing are more serious symptoms and
require urgent medical attention.
Wash hands after use.
In the event of self-injection, seek medical advice.

Penicillins should not be administered concurrently with bacteriostatic
antibiotics.

Revised: August 2025
MA split from NI MA following AN: 01377/2025

Do not store above 25C.
Discard unused suspension.
Keep the container in the outer carton.

suspension per 100 kg bodyweight.
Shake well before administration.
For intramuscular use. Do not administer intravenously.
To ensure a correct dosage, bodyweight should be determined as accurately as
possible to avoid under-dosing.
4.10 Overdose (symptoms, emergency procedures, antidotes), if necessary
Penicillins have a very wide margin of safety.
4.11 Withdrawal period(s)
Cattle meat and offal: 7 days
Cattle milk: 96 hours
5

This information is sourced from the official Summary of Product Characteristics (SPC) published by the Veterinary Medicines Directorate (VMD). It is provided for informational purposes only and does not replace professional veterinary advice. Always consult your vet before administering any medication.