Naloxone injection

Because you will receive naloxone in an emergency situation, you are not likely to miss a dose.

Avoid leaving a person alone after giving him or her a naloxone injection. An overdose can impair a person's thinking or reactions.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

• Abdominal or stomach cramps
• body aches
• convulsions
• diarrhea
• difficult or troubled breathing
• excessive crying
• fast, pounding, or irregular heartbeat or pulse
• fever
• goosebumps
• increased or excessive unconscious or jerking movements
• irregular, fast or slow, or shallow breathing
• irritability
• nausea or vomiting
• nervousness
• pale or blue lips, fingernails, or skin
• restlessness
• runny nose
• shivering
• sneezing
• sweating
• trembling
• weakness
• yawning

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

• If you have an allergy to naloxone or any other part of naloxone injection.
• If you are allergic to any drugs like this one, any other drugs, foods, or other substances. Tell your doctor about the allergy and what signs you had, like rash; hives; itching; shortness of breath; wheezing; cough; swelling of face, lips, tongue, or throat; or any other signs.

This medicine may interact with other drugs or health problems.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take this medicine with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
• Signs of high or low blood pressure like very bad headache or dizziness, passing out, change in eyesight.
• Seizures.
• Shortness of breath.
• Chest pain or pressure or a fast heartbeat.
• A heartbeat that does not feel normal.
• A burning, numbness, or tingling feeling that is not normal.
• Feeling agitated.
• Mood changes.
• Hallucinations (seeing or hearing things that are not there).
• Shakiness.
• Sweating a lot.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Upset stomach or throwing up.
• Dizziness.
• Irritation where the shot is given.
• Hot flashes.
• Flushing.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-FDA-1088. You may also report side effects at http://www.fda.gov/medwatch.

• If you need to store this medicine at home, talk with your doctor, nurse, or pharmacist about how to store it.

Complete or Partical Reversal of Opioid Depression

Naloxone hydrochloride prevents or reverses the effects of opioids including respiratory depression, sedation, and hypotension. Also, it can reverse the psychotomimetic and dysphoric effects of agonist-antagonist such as pentazocine.

Naloxone hydrochloride is an essentially pure opioid antagonist, i.e., it does not possess the "agonistic" or morphine-like properties characteristic of other opioid antagonists. When administered in usual doses and in the absence of opioids or agonistic effects of other opioid antagonists, it exhibits essentially no pharmacologic activity.

Naloxone hydrochloride has not been shown to produce tolerance or cause physical or psychological dependence. In the presence of physical dependence on opioids, naloxone hydrochloride will produce withdrawal symptoms. However, in the presence of opioid dependence, opiate withdrawal symptoms may appear within minutes of naloxone hydrochloride administration and subside in about 2 hours. The severity and duration of the withdrawal syndrome are related to the dose of naloxone hydrochloride and to the degree and type of opioid dependence.

While the mechanism of action of naloxone hydrochloride is not fully understood, in vitro evidence suggests that naloxone hydrochloride antagonizes opioid effects by competing for the u, k and o opiate receptor sites in the CNS, with the greatest affinity for the u receptor.

When naloxone hydrochloride is administered intravenously (I.V.), the onset of action is generally apparent within two minutes. The onset of action is slightly less rapid when it is administered subcutaneously (S.C.) or intramuscularly (I.M.). The duration of action is dependent upon the dose and route of administration of naloxone hydrochloride. Intramuscular administration produces a more prolonged effect than intravenous administration. Since the duration of action of naloxone hydrochloride may be shorter than that of some opiates, the effects of the opiate may return as the effects of naloxone hydrochloride dissipates. The requirement for repeat doses of naloxone hydrochloride will also be dependent upon the amount, type and route of administration of the opioid being antagonized.

Adjunctive Use in Septic Shock

Naloxone hydrochloride has been shown in some cases of septic shock to produce a rise in blood pressure that may last up to several hours; however, this pressor response has not been demonstrated to improve patient survival. In some studies, treatment with naloxone hydrochloride in the setting of septic shock has been associated with adverse effects, including agitation, nausea and vomiting, pulmonary edema, hypotension, cardiac arrhythmias, and seizures. The decision to use naloxone hydrochloride in septic shock should be exercised with caution, particularly in patients who may have underlying pain or have previously received opioid therapy and may have developed opioid tolerance.

Because of the limited number of patients who have been treated, optimal dosage and treatment regimens have not been established.

Distribution

Following parenteral administration, naloxone hydrochloride is rapidly distributed in the body and readily crosses the placenta. Plasma protein binding occurs but is relatively weak. Plasma albumin is the major binding constituent but significant binding of naloxone also occurs to plasma constituents other than albumin. It is not known whether naloxone is excreted into human milk.

Metabolism and Elimination

Naloxone hydrochloride is metabolized in the liver, primarily by glucuronide conjugation with naloxone-3-glucoronide as the major metabolite. In one study the serum half-life in adults ranged from 30 to 81 minutes (mean 64 ± 12 minutes). In a neonatal study the mean plasma half-life was observed to be 3.1 ± 0.5 hours. After an oral or intravenous dose, about 25-40% of the drug is excreted as metabolites in urine within 6 hours, about 50% in 24 hours, and 60-70% in 72 hours.

Naloxone hydrochloride is an opioid antagonist. Physical dependence associated with the use of naloxone hydrochloride has not been reported. Tolerance to the opioid antagonist effect of naloxone hydrochloride is not known to occur.