Penstrep-400 (Procaine Penicillin G + Dihydrostreptomycin) Injectable Suspension – Broad-Spectrum Antibiotic for Cattle, Sheep, Goats & Pigs | 100ml

What Is Penstrep-400?

Penstrep-400 is a sterile white suspension for intramuscular injection manufactured by Interchemie, combining two established veterinary antibiotics in a single preparation:

• Procaine penicillin G — 200,000 IU per ml
• Dihydrostreptomycin sulphate — 200mg per ml

The combination provides bactericidal coverage across both Gram-positive and Gram-negative bacterial species — a broader spectrum than either agent alone — making Penstrep-400 a practical first-line injectable antibiotic for mixed or unconfirmed bacterial infections in farm livestock.

How the Two Active Ingredients Work Together

Procaine Penicillin G — Cell Wall Synthesis Inhibitor (Gram-Positive Focus)

Procaine penicillin G is a depot formulation of benzylpenicillin (penicillin G) combined with procaine to slow absorption and extend the duration of activity following IM injection. Penicillin kills bacteria by inhibiting transpeptidase enzymes (penicillin-binding proteins) that cross-link peptidoglycan strands in the bacterial cell wall. Without this cross-linking, the cell wall is structurally defective and the bacterium ruptures under osmotic pressure.

Penicillin G is primarily active against Gram-positive organisms, whose thick peptidoglycan cell walls are the drug’s primary target. It has limited activity against Gram-negative bacteria (which have an outer membrane that restricts penicillin access) and no activity against penicillinase-producing (beta-lactamase-positive) organisms.

Dihydrostreptomycin — Protein Synthesis Inhibitor (Gram-Negative Focus)

Dihydrostreptomycin is an aminoglycoside antibiotic that kills bacteria by binding irreversibly to the 30S subunit of the bacterial ribosome, disrupting the initial step of protein synthesis. This causes misreading of the genetic code during translation, producing non-functional proteins and ultimately bacterial cell death. Dihydrostreptomycin is primarily active against Gram-negative aerobic bacteria — complementing penicillin’s Gram-positive focus.

Why the Combination Is More Effective Than Either Agent Alone

The combination acts additively and in some cases synergistically. Procaine penicillin G weakens the bacterial cell wall, which can enhance the uptake of dihydrostreptomycin into bacteria (aminoglycosides are energy-dependent in their transport and require intact membrane potential). Together, the two antibiotics simultaneously attack two independent bacterial targets — the cell wall and ribosomal protein synthesis — making resistance development substantially harder than with single-agent therapy.

Target Bacteria

Penstrep-400 is active against the following organisms (subject to sensitivity testing):

Indications

Penstrep-400 is indicated for the treatment of the following conditions in cattle, calves, sheep, goats, and pigs caused by sensitive organisms:

• Arthritis — bacterial joint infections in calves, lambs, piglets, and adult animals
• Mastitis — acute and subacute udder infections
• Respiratory tract infections — pneumonia, bronchopneumonia, pleurisy
• Gastrointestinal infections — bacterial enteritis, colibacillosis (neonatal scours)
• Urinary tract infections
• Erysipelas in pigs
• Listeriosis (circling disease) in ruminants
• Secondary bacterial infections complicating viral disease

Dosage

Penstrep-400 is administered by deep intramuscular (IM) injection once daily for 3 consecutive days. Shake the bottle thoroughly before each use.

Worked Dosage Examples

How Many Doses Does the 100ml Bottle Provide?

Administration Instructions

1. Shake the bottle vigorously before each use — Penstrep-400 is a suspension that settles; inadequate mixing results in inaccurate dosing
2. Use a sterile needle appropriate for deep IM injection (typically 18–16 gauge for cattle; 20 gauge for smaller animals)
3. Inject into the deep muscle mass — preferred sites are the neck musculature or hindquarter (avoid the rump in animals close to slaughter to prevent injection-site lesions in the meat)
4. If the required dose exceeds the maximum per-site volume, divide the total volume and inject into two separate sites
5. Rotate injection sites between daily doses
6. Do not mix with other drugs in the same syringe

Withdrawal Periods

Note: Kidney withdrawal is longer than meat withdrawal due to dihydrostreptomycin accumulation in renal tissue. Kidneys should not be used for human consumption until 45 days after the last treatment. Always verify against the product label registered in your country.

⚠️ Critical Warnings

Sow Abortion Risk

Administration of therapeutic doses of procaine penicillin G to pregnant sows can result in abortion. Procaine (the salt carrier that extends penicillin absorption) has uterotonic effects in pigs. Do not use Penstrep-400 in pregnant sows unless the clinical benefit to the sow is assessed to outweigh this risk under veterinary supervision.

DO NOT USE in Small Herbivores — Fatal Penicillin Toxicity

Penstrep-400 must never be administered to rabbits, guinea pigs, hamsters, gerbils, or other small herbivorous animals. Penicillin-class antibiotics cause fatal disruption of the gut flora in these species, leading to overgrowth of Clostridium difficile and related organisms, producing rapidly fatal enterotoxaemia. Even a single therapeutic dose can be lethal. Penstrep-400 is indicated only for cattle, calves, sheep, goats, and pigs.

Ototoxicity and Nephrotoxicity from Dihydrostreptomycin

Dihydrostreptomycin, like all aminoglycosides, has potential for ototoxicity (damage to the cochlea and vestibular apparatus of the inner ear, potentially causing permanent hearing loss and balance disorders) and nephrotoxicity (tubular damage to the kidney). These risks are greatest with overdosage, prolonged treatment beyond 3 days, or in animals with pre-existing renal impairment. Stick strictly to the 3-day treatment course and do not exceed the recommended dose.

Contraindications

• Hypersensitivity to penicillins, procaine, or aminoglycosides — anaphylactic reactions can be severe and fatal; have adrenaline available for emergency use
• Significantly impaired renal function — dihydrostreptomycin accumulates in renal failure, dramatically increasing ototoxicity and nephrotoxicity risk
• Rabbits, guinea pigs, hamsters, and other small herbivores — fatal penicillin enterotoxaemia (see warning above)
• Concurrent use with bacteriostatic antibiotics — see drug interactions below

Drug Interactions

The key principle: penicillin G is bactericidal and depends on bacterial cell division to work. Bacteriostatic antibiotics that halt cell growth (tetracyclines, macrolides, chloramphenicol, lincosamides) directly antagonise this mechanism. These combinations should not be used simultaneously.

Side Effects

• Sow abortion — due to uterotonic effect of procaine at therapeutic doses in pregnant pigs
• Pyrexia, vomiting, shivering, listlessness, incoordination — occasionally seen in suckling and fattening pigs; usually transient
• Ototoxicity — vestibular and cochlear damage from dihydrostreptomycin; risk increases with overdose or prolonged use
• Nephrotoxicity — tubular damage from dihydrostreptomycin accumulation; especially in renally compromised animals
• Neurotoxicity — at high doses or in animals with impaired drug elimination
• Hypersensitivity reactions — from mild urticaria to severe anaphylaxis; more common with penicillin. Monitor animals for 20–30 minutes after first injection.
• Injection site reactions — local swelling and muscle soreness; rotate sites between doses

Storage

• Store below 25°C, protected from light
• Do not freeze
• Keep in original container
• Penstrep-400 is a suspension — shake vigorously before every use
• Once broached, use under strict aseptic conditions; multi-dose vials should be used within a reasonable time frame
• Keep out of reach of children

Frequently Asked Questions

Why does Penstrep-400 contain two antibiotics?

Because penicillin G is active mainly against Gram-positive bacteria, while dihydrostreptomycin is active mainly against Gram-negative bacteria. Most livestock bacterial infections involve either Gram-negative organisms (like E. coli, Pasteurella, Salmonella) or mixed Gram-positive/Gram-negative infections. Using both together in one product covers the full spectrum with a single injection, rather than requiring two separate products.

Can Penstrep-400 be used in horses?

The Penstrep-400 product label specifies cattle, calves, sheep, goats, and swine. While similar pen-strep combination products are registered for horses in some countries, Penstrep-400 itself does not list horses as a target species. Do not use off-label in horses without specific veterinary guidance — and never use penicillin in any route in rabbits, guinea pigs, or small herbivores.

Why does the kidney withdrawal period (45 days) differ so much from meat (21 days)?

Dihydrostreptomycin is an aminoglycoside that selectively accumulates and persists in renal proximal tubular cells far longer than it remains in general muscle tissue. Even after the drug has cleared from bloodstream and muscle, significant concentrations remain in the kidney. The 45-day kidney withdrawal ensures that kidney tissue entering the human food chain contains no detectable residues.

What should I do if an animal has a severe reaction after Penstrep-400 injection?

Penicillin anaphylaxis, while rare in livestock, can be severe. Signs include sudden collapse, pale mucous membranes, laboured breathing, and swelling. Have adrenaline (epinephrine) available when treating animals with any penicillin product for the first time. Administer adrenaline immediately if severe hypersensitivity occurs and contact your veterinarian. Do not administer Penstrep-400 again to any animal that has shown a hypersensitivity reaction.

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