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This page contains information on Twin-Pen for veterinary use.
The information provided typically includes the following:
  • Twin-Pen Indications
  • Warnings and cautions for Twin-Pen
  • Direction and dosage information for Twin-Pen


This treatment applies to the following species:
Manufacturer: AgriLabs


penicillin G benzathine and penicillin G procaine Aqueous Suspension

Veterinary Injection for Use in Beef Cattle

NADA 65-498, Approved by FDA

For Subcutaneous Use Only



Each mL contains 150,000 units penicillin G benzathine; 150,000 units penicillin G procaine and, approximately: 0.08% sodium carboxymethylcellulose; 0.40% sodium citrate dihydrate; 1.17% lecithin; 0.31% povidone; 0.04% polysorbate 40; 0.06% sorbitan monopalmitate 40; 0.01% propylparaben, 0.12% methylparaben, and 0.25% phenol as preservatives; trisodium phosphate, as required to adjust pH; water for injection q.s.


Penicillin G is an antibiotic which shows a marked bactericidal effect against certain organisms during their growth phase. It is relatively specific in its action against gram-positive bacteria but is usually ineffective against gram-negative organisms.

It is normally recommended that any bacterial infection be treated as early as possible and with a dosage which will give effective blood levels. Although the recommended dosage of Twin-Pen® will give longer detectable penicillin blood levels than penicillin G procaine alone, it is recommended that a second dose be administered at 48 hours when treating a penicillin-susceptible bacterial infection.

The use of antibiotics in the management of disease is based on an accurate diagnosis and an adequate course of treatment. When properly used in the treatment of diseases caused by penicillin-susceptible organisms, most animals treated with Twin-Pen® show a noticeable improvement within 24 to 48 hours. If improvement does not occur within this period of time, the diagnosis and course of treatment should be re-evaluated. It is recommended that the diagnosis and treatment of animal diseases be carried out by a veterinarian. Since many diseases look alike but require different types of treatment, the use of professional veterinary and laboratory services can reduce treatment time, costs, and needless losses. Good housing, sanitation, and nutrition are important in the maintenance of healthy animals and are essential in the treatment of disease.


Beef cattle should be withheld from slaughter for food use for 30 days following last treatment. Treatment in beef cattle must be limited to two (2) doses, BY SUBCUTANEOUS INJECTION ONLY. Do not inject intramuscularly. A withdrawal period has not been established in pre-ruminating calves. Do not use in veal calves.

Twin-Pen Indications: Twin-pen® Is Indicated For Treatment Of The Following Bacterial Infections In Beef Cattle Due To Penicillin-susceptible Micro-organisms That Are Susceptible To The Serum Levels Common To This Particular Dosage Form, Such As:

1. Bacterial Pneumonia (shipping Fever Complex) (streptococcus Spp., corynebacterium Pyogenes, staphylococcus Aureus)

2. Upper Respiratory Infections Such As Rhinitis Or Pharyngitis (corynebacterium Pyogenes)

3. Blackleg (clostridium Chauvoei)


Exceeding the recommended doses and dosage levels may result in antibiotic residues beyond the withdrawal time. Do not inject this material intramuscularly.

Penicillin G is a substance of low toxicity. However, side effects, or so-called allergic or anaphylactic reactions - sometimes fatal, have been known to occur in animals hypersensitive to penicillin and procaine. Such reactions can occur unpredictably with varying intensity. Animals administered penicillin G should be kept under close observation for at least one-half hour. Should allergic or anaphylactic reactions occur, discontinue use of the product and immediately administer epinephrine following manufacturer’s recommendations; call a veterinarian.

As with all antibiotic preparations, use of this drug may result in overgrowth of nonsusceptible organisms, including fungi. A lack of response by the treated animal, or the development of new signs or symptoms suggest that an overgrowth of nonsusceptible organisms has occurred. In such instances, consult your veterinarian.

Since bactericidal drugs may interfere with the bacteriostatic action of tetracyclines, it is advisable to avoid giving penicillin in conjunction with tetracyclines.

Twin-Pen® should be stored under refrigeration 2°-8°C (36°-46°F). Avoid freezing. Warm to room temperature, and shake well before using.


The recommended dosage for beef cattle should be administered by SUBCUTANEOUS INJECTION ONLY. Failure to use the subcutaneous route of administration may result in antibiotic residues in meat beyond the withdrawal time.


Beef Cattle: 2 mL per 150 lb body weight GIVEN SUBCUTANEOUSLY ONLY (2,000 units penicillin G procaine and 2,000 units penicillin G benzathine per lb body weight). Treatment should be repeated in 48 hours.


Treatment in beef cattle should be limited to two (2) doses given by subcutaneous injection only.

Directions For Use

A thoroughly cleaned, sterile needle and syringe should be used for each injection (needles and syringes may be sterilized by boiling in water for 15 minutes). Before withdrawing the solution from the bottle, disinfect the rubber cap on the bottle with a suitable disinfectant, such as 70 percent alcohol. The injection site should be similarly cleaned with the disinfectant. Needles of 14 to 16 gauge and not more than 1 inch long are adequate for injections.

A subcutaneous injection should be made by pinching up a fold of the skin between the thumb and forefinger. The mid-neck region is the preferred injection site. Insert the needle under the fold in a direction approximately parallel to the surface of the body. When the needle is inserted in this manner the medication will be delivered underneath the skin between the skin and the muscles. Proper restraint, such as the use of a chute and nose lead, is needed for proper administration of the product.


For Animal Use Only

Restricted Drug(s) (california)

Not For Human Use

Use Only As Directed

PACKAGE INFORMATION: Twin-Pen® is available in vials of 100 mL, 250 mL and 500 mL with each mL containing 150,000 units of penicillin G benzathine and 150,000 units of penicillin G procaine. The 500 mL vial is intended for use with automatic syringes.

® Registered trademark of Agri Laboratories, Ltd.


Manufactured for Agri Laboratories, Ltd., St. Joseph, MO 64503



100 mL


250 mL

T-Rev 1105

500 mL


Nac No.

20927 STATE ROUTE K, P.O. BOX 3103 (64503), ST. JOSEPH, MO, 64505
Telephone:   816-233-9533
Order Desk:   800-542-8916
Fax:   816-233-9546
Every effort has been made to ensure the accuracy of the Twin-Pen information published above. However, it remains the responsibility of the readers to familiarize themselves with the product information contained on the US product label or package insert.

Copyright © 2018 North American Compendiums. Updated: 2018-04-26