1 What is Unasyn?

Brand: Unasyn

Generic: Ampicillin and Sulbactam

Unasyn is a broad spectrum β-lactam antibiotic which is bactericidal but it kills only when bacteria are growing and synthesizing cell wall.

This drug inhibits the synthesis of bacterial cell wall peptidoglycan by inhibiting transpeptidation enzyme (transpeptidase). It also inactivates the inhibitor of autolytic enzymes in the bacterial cell wall.

This causes activation of the autolytic enzyme (e.g. murein hydrolases), which degrades the peptidoglycan and thus causes lysis of the bacterium.

On the contrary, ampicillin is found inactive against organisms devoid of peptidoglycan cell walls, such as mycobacteria, protozoa, fungi, and viruses.

Unasyn is usually prescribed by the physicians to treat the patients with certain diseases like:

Although Unasyn is effective against both gram positive and gram negative organisms, it is destroyed by β-lactamase. That’s why Unasyn is often used with a potent β-lactamase inhibitor named sulbactam.

Thus, ampicillin and sulbactam combination is used to treat certain bacterial infections in many different parts of the body caused by a variety of β-lactamase producing bacteria such as staphylococci, H. influenzae, N. gonorrhea, Salmonella, Shigella, E. coli, and K. pneumoniae.

This combination medicine is generally given only by or under the direct supervision of a healthcare professional. This combination drug is available in powder form that is later dissolved in sterile water to make a solution at the time of injection.

2 What to Know Before Using

Before using Unasyn, you must know all about the risks and complications associated with it. This is a decision that your doctor will make with your active participation.

There are some important factors such as drug interaction, metabolic impairment, hypersensitivity reaction, pregnancy, lactation etc. which may alter the desired effects of such medications.

Sometimes the presence of other health disorders affects the beneficial effects of this medicine and even may cause serious complications. Make sure you mention your doctor if you have any other medical problems.

The use of this combination medicine is contraindicated in those patients who have known hypersensitivity to any component of this medication or to any other β-lactam antibiotic (e.g. cephalosporin). Further, you should not use this drug if you have mononucleosis, hepatic and/or renal disorders.

In addition, certain drugs should not be used concurrently with such medications. It is always recommended to consult with your doctor if you are in need of some drugs for another health problem in order to avoid unwanted serious effects.

You should not use the following drugs concurrently along with this combination medicine:

  • Tetracyclines: they may decrease ampicillin/sulbactam's effectiveness.
  • Probenecid: it may increase the risk of ampicillin/sulbactam's side effects.
  • Allopurinol: the risk of skin rash may be increased because of this drug.
  • Heparin: it increases the risk of bleeding in the susceptible individuals.
  • Methotrexate: the risk of its side effects may be increased by ampicillin/sulbactam.
  • Anticoagulants: their effectiveness may be reduced or the risk of their side effects may be increased by ampicillin/sulbactam.
  • Aminoglycosides, birth control pills, or live oral typhoid vaccine: their effectiveness may be decreased by ampicillin/sulbactam.

Furthermore, animal reproduction studies have failed to demonstrate a risk to the fetus and there are no adequate and well-controlled studies in pregnant women. Thus, this medicine can be used during pregnancy if clearly needed.

3 Proper Usage

To use Unasyn properly, you must follow all instructions given by your doctor. The frequency of your daily drug administration and the duration of drug therapy depend on the particular medical problem for which you are taking the medicine. That’s why the therapeutic dose may vary with patient’s condition or requirement.

This combination medicine is usually given to the patients by a nurse or other trained healthcare professional in a hospital. Deep intramuscular or intravenous administration of 1-2 vials of such combination medicine at every 6 hours interval is usually recommended to treat susceptible infections. Each vial contains 1 g ampicillin and 0.5 g sulbactam.

You should take this medicine in time until the prescribed course is finished. If you miss any dose of this medicine, you should take it as soon as possible. But if it is time for your next dose, then you should skip the missed dose and go back to your regular treatment schedule.

You should store the medicine in a closed container at room temperature away from heat, moisture, and direct light. All kinds of medicines should be kept out of the reach of children. It is advised to dispose of an outdated medicine by an appropriate way.

4 Precautions to Take

In using Unasyn, you must be careful and take some precautions as advised by your doctor. Unasyn is one of the semisynthetic penicillins and all forms of penicillins can cause hypersensitivity reactions.

The incidence of such allergic reactions is more commonly reported after parenteral administration but the course of hypersensitivity is unpredictable. That’s why history of penicillin or other β-lactam antibiotic allergy must be elicited before injecting it.

A scratch test or intradermal test (with 2-10 U) may be performed first. Testing with benzyl-penicilloyl-polylysine is safer. However, a negative intradermal test does not rule out delayed hypersensitivity. 

Moreover, regular visits are recommended to make sure penicillin is working properly or not while you are receiving this drug therapy.

5 Potential Side Effects

As with many medications, there are several potential side effects associated with Unasyn. These side-effects usually go away during the treatment episode as your body adjusts to the medicine.

Your healthcare professional may advise you about the ways how to prevent or reduce those unwanted side-effects.

Sometimes you may need to consult with the doctor if you feel any of the following serious toxic effects:

  • Pain at the site of injection, thrombophlebitis of injected vein, discoloration of the skin, hives, itching, bleeding, and diarrhea are the main adverse effects.
  • A high incidence (up to 10%) of rashes is reported, especially in patients with AIDS, EB virus infections or lymphatic leukemia. Sometimes the rashes may not be allergic, but toxic in nature.
  • Chest discomfort, white patches, painful urination, swelling of the abdominal area, redness, or soreness of the tongue may also occur following such drug therapy, but rarely.