Penicillin G

(pen-i-sill-in jee)

Description: Beta Lactam Antibiotic

Other names for this medication: Pfizerpen®, VetOne Pro®, VetriPen G®

Penicillin G is usually given by injection; oral administration is uncommon.

•Procaine penicillin G should not be given intravenously (in the vein).

•Injectable liquid solutions may cause stinging when injected under the skin (SC, subcutaneously).

How is this medication useful?

Penicillin G is an antibiotic that can be helpful to treat certain bacterial infections. The FDA has approved penicillin G for use in animals.

You and your veterinarian can discuss why this drug is the most appropriate choice.

What should I tell my veterinarian to see if this medication can be safely given?

Many things might affect how well this drug will work in your animal. Be sure to discuss the following with your veterinarian so together you can make the best treatment decisions.

•Other drugs can interact with penicillin G, so be sure to tell your veterinarian and pharmacist what medications (including vitamins, supplements, or herbal therapies) you give your animal, including the amount and time you give each.

•Tell your veterinarian about any conditions or diseases your animal may have now or has had in the past.

•If your animal has been treated for the same disease or condition in the past, tell your veterinarian about the treatment and how well it did or didn’t work.

•If your animal is pregnant or nursing, talk to your veterinarian about the risks of using this drug.

•Tell your veterinarian and pharmacist about any medication side effects (including allergic reactions, lack of appetite, diarrhea, itching, hair loss) your animal has developed in the past.

How long until I will know if this medication is working, and how long will the effects of this medication last?

This medication should start having effects within 1 to 2 hours; however, you may not see the effects of this medication outwardly. Your animal should begin feeling better within 1 to 2 days.

The effects of this medication are short-lived, meaning they will stop working within 24 hours, although the benefits may be prolonged if your animal has decreased kidney and/or liver function.

When should this medication not be used or be used very carefully?

No drug is 100% safe in all patients, but your veterinarian will discuss with you any specific concerns about using this drug in your animal.

This drug SHOULD NOT be used in patients:

•That are allergic to it or drugs like it (other penicillins).

This drug should be used WITH CAUTION in patients:

•That have electrolyte disorders or heart disease.

•That have a history of an allergic reaction this drug or related antibiotics (eg, cephalosporins).

•Penicillin G procaine should be used cautiously, if at all, in snakes, rabbits, guinea pigs, gerbils, hamsters, or chinchillas, as they may be more sensitive or reactive to this form of the antibiotic.

If your animal has any of these conditions, talk to your veterinarian about the potential risks versus benefits.

What are the side effects of this medication?

Common but not serious side effects include:

•Diarrhea, vomiting, and loss of appetite.

•Stinging at the injection site.

You don’t have to be overly concerned if you see any of these signs unless they are severe, worsen, or continue to be a problem. Contact your veterinarian if this happens.

Side effects that may be serious or indicate a serious problem:

•Complete loss of appetite in cats may cause severe liver problems.

•Fever, rashes, trouble breathing, and pale gums may be symptoms of allergic reactions.

If you see any of these signs, contact your veterinarian immediately.

If my animal gets too much of this medication (an overdose), what should I do?

Overdoses of penicillin G can be serious and can cause electrolyte imbalances and damage to the nervous system and liver. If you witness or suspect an overdose, contact your veterinarian or an animal poison control center for further advice. Animal poison control centers that are open 24 hours a day include: Pet Poison HELPLINE (855-764-7661) and ASPCA Animal Poison Control Center (888-426-4435); a consultation fee is charged for these services.

How should this medication be given?

For this medication to work, give it exactly as your veterinarian has prescribed. It’s a good idea to always check the prescription label to be sure you are giving the drug correctly.

By Injection:

•Your veterinarian or pharmacist will give you all of the items you need to give the injections (eg, needles, syringes). If the medicine needs to be mixed before you give it, mix it exactly as your veterinarian or pharmacist instructs you.

•Use a new needle and new syringe to mix each vial and to give each shot. Do not reuse needles and syringes.

•Because this drug must be injected, be sure you understand the proper dosage, location(s), and method for giving the shots.

For Penicillin G potassium or sodium:

•It is very important to equalize the pressure in a vial of penicillin when adding diluent (liquid). Your pharmacist or veterinarian will show you how to add diluent in a way that does not cause the penicillin to spray back out of the vial.

•After adding the diluent (liquid), shake vials of penicillin G sodium or potassium until the liquid is clear. Your veterinarian will usually have you dilute the entire vial of penicillin G in another bag of fluids for administration under the skin.

•These solutions break down quickly if not mixed exactly as instructed and must be stored in the refrigerator. Once the solution is mixed, the expiration date varies but can be no longer than 7 days. Do not use any mixed penicillin G after this expiration date.

For Procaine Penicillin G:

•This injection should be shaken very well before each administration. Make sure that there is not a layer of penicillin G procaine sitting on the bottom of the vial before you give it. Procaine penicillin G must be given in the muscle and not in the vein.

•Solution may sting when injected. If your animal objects to the injections too much, your veterinarian may be able to give you something to mix with the penicillin G to decrease stinging.

•These medications can be given for various lengths of time. Be sure you understand how long your veterinarian wants you to continue giving this medication. Prescription refills may be necessary before the therapy will be complete. Before stopping this medication, talk to your veterinarian, as there may be important reasons to continue its use.

What should I do if I miss giving a dose of this medication?

If you miss a dose, give it when you remember, but if it is close to the time for the next dose, skip the dose you missed and give it at the next scheduled time. After that, return to the regular dosing schedule. Do not double-up or give extra doses.

How should I store this medication?

•Store these medications in the original prescription bottle, vial, or another container provided by your pharmacist or veterinarian.

•Dry vials of the powder may be stored at room temperature but once mixed, the liquid must be stored in the refrigerator. Procaine Penicillin G must be refrigerated at all times.

•If your veterinarian or pharmacist has made (compounded) a special formulation for your animal, follow the storage recommendations and expiration date for the product.

•Keep away from children and other animals.

Can handling this medication be hazardous to me, my family, or other animals?

There are no specific precautions required when handling this medication unless you are allergic to it. Wash your hands after handling any medication.

How should I dispose of this medication if I don’t use it all?

•Do not flush this medication down the toilet or wash it down the sink. If a community drug “take-back” program is available, use this option. If there is no take-back program, mix the drug with coffee grounds or cat litter (to make it undesirable to children and animals and unrecognizable to people who might go through your trash), place the mixture in a sealable plastic bag to keep it from leaking out, and throw the bag out with the regular trash.

•Do not save leftover medication for future use or give it to others to use.

What other information is important for this medication?

Use of this drug may not be allowed in certain animal competitions. Check rules and regulations before entering your animal in a competition while this medication is being administered.