Antibiotic (Long-acting Penicillin)
Last reviewed July 2026
Who is this for?
Benzathine benzylpenicillin (sold as Bentarpen Injection in Nigeria) is a long-acting antibiotic injection that kills bacteria by breaking down their protective walls, allowing one injection to keep working in your body for weeks.
Inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins and preventing cross-linking of peptidoglycan strands, leading to bacterial cell lysis and death. The long-acting depot formulation provides sustained antimicrobial activity over weeks, making it ideal for infections requiring prolonged therapy.
Prescription Required
You need a doctor's prescription to buy this drug.
Explore this drug
If you miss a scheduled injection appointment (especially for rheumatic fever prevention), go to your clinic as soon as possible to get it. Do not wait until the next scheduled date, as the sooner you get it, the better your protection.
Important for antibiotics
Always complete the full course even if you feel better. Stopping early can cause the infection to return and become drug-resistant.
Always get this injection at a proper hospital, clinic, or registered pharmacy, never from roadside medicine sellers or unqualified people. If your doctor prescribes a series of injections (e.g. monthly for rheumatic fever), complete the full course even if you feel fine. After receiving the injection, stay at the clinic for at least 30 minutes so they can watch you for any allergic reaction.
Methotrexate (used for arthritis and some cancers): penicillin can increase its side effects. Probenecid (used for gout) makes penicillin stay longer in the body, which your doctor may sometimes use on purpose. Blood-thinning drugs like warfarin may need dose adjustment when used together with this injection.
Check your specific combination
Is it safe to take Benzathine with your other drugs?
Benzathine benzylpenicillin is generally considered safe during pregnancy and breastfeeding. In fact, it is the recommended treatment for syphilis in pregnant women, but always let your doctor know you are pregnant before receiving it.
Store the injection vial or powder in a cool, dry place away from direct sunlight and heat. In Nigeria's hot climate, keep it below 25°C if possible; a cool cupboard works. Keep away from children. Once mixed by the pharmacist or nurse, it should be used immediately.
For information only: not medical advice. Always talk to a doctor or pharmacist before changing your medication.
Names this drug is sold under, especially in Nigerian and West African pharmacies
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Counterfeit Drug Warning
Fake drugs are a serious problem in Nigeria. Always buy from a registered pharmacy. If the packaging looks different from what is described above, do not use it.