AMPHADASE

Amphadase^® is indicated as an adjuvant in subcutaneous fluid administration for achieving hydration.

Amphadase^® is indicated as an adjuvant to increase the dispersion and absorption of other injected drugs.

Amphadase^® is indicated as an adjunct in subcutaneous urography for improving resorption of radiopaque agents.

Insert needle with aseptic precautions. With tip lying free and movable between skin and muscle, begin clysis; fluid should start in readily without pain or lump. Then inject Amphadase^® (hyaluronidase injection) into rubber tubing close to needle.

An alternate method is to inject Amphadase^® under skin prior to clysis. 150 units will facilitate absorption of 1,000 mL or more of solution. As with all parenteral fluid therapy, observe effect closely, with same precautions for restoring fluid and electrolyte balance as in intravenous injections. The dose, the rate of injection, and the type of solution (saline, glucose, Ringer’s, etc.) must be adjusted carefully to the individual patient. When solutions devoid of inorganic electrolytes are given by hypodermoclysis, hypovolemia may occur. This may be prevented by using solutions containing adequate amounts of inorganic electrolytes and/or controlling the volume and speed of administration.

Amphadase^® may be added to small volumes of solution (up to 200 mL), such as small clysis for infants or solutions of drugs for subcutaneous injection. For infants and children less than 3 years old, the volume of a single clysis should be limited to 200 mL; and in premature infants or during the neonatal period, the daily dosage should not exceed 25 mL/kg of body weight; the rate of administration should not be greater than 2 mL per minute. For older patients, the rate and volume of administration should not exceed those employed for intravenous infusion.

Absorption and dispersion of other injected drugs may be enhanced by adding 50 units to 300 units, most typically 150 units hyaluronidase, to the injection solution.

The subcutaneous route of administration of urographic contrast media is indicated when intravenous administration cannot be successfully accomplished, particularly in infants and small children. With the patient prone, 75 units of Amphadase^® (hyaluronidase injection) is injected subcutaneously over each scapula, followed by injection of the contrast medium at the same sites.

Hypersensitivity to hyaluronidase or any other ingredient in the formulation is a contraindication to the use of this product.

Hyaluronidase should not be injected into or around an infected or acutely inflamed area because of the danger of spreading a localized infection.
Hyaluronidase should not be used to reduce the swelling of bites or stings.

Hyaluronidase should not be applied directly to the cornea.

Hyaluronidase should not be used for intravenous injections because the enzyme is rapidly inactivated.

Furosemide, the benzodiazepines and phenytoin have been found to be incompatible with hyaluronidase.

Admixture stability studies have shown that 2% lidocaine with 1:100,000 or 1:200,000 epinephrine is incompatible with hyaluronidase due to the presence of sodium metabisulfite, a common additive in anesthetic products containing epinephrine.

Hyaluronidase should not be used to enhance the dispersion and absorption of dopamine and/or alpha agonist drugs.

When considering the administration of any other drug with hyaluronidase, it is recommended that appropriate references first be consulted to determine the usual precautions for the use of the other drug; e.g., when epinephrine is injected along with hyaluronidase, the precautions for the use of epinephrine in cardiovascular disease, thyroid disease, diabetes, digital nerve block, ischemia of the fingers and toes etc., should be observed.

When hyaluronidase is added to a local anesthetic agent, it hastens the onset of analgesia and tends to reduce the swelling caused by local infiltration, but the wider spread of the local anesthetic solution increases its absorption; this shortens its duration of action and tends to increase the incidence of systemic reaction.

Patients receiving large doses of salicylates, cortisone, , adrenocorticotropic hormone (ACTH), estrogens or antihistamines may require larger amounts of hyaluronidase for equivalent dispersing effect, since these drugs apparently render tissues partly resistant to the action of hyaluronidase.

Risk Summary

Human studies of hyaluronidase as an aid to conception and as an aid to delivery have been conducted without reports of maternal or fetal harm. There are no available data on Amphadase^® use in pregnant women to evaluate for a drug-associated risk of major birth defects, miscarriage or other adverse maternal or fetal outcomes. Animal reproduction studies have not been conducted with Amphadase^®.

The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. However, the background risk in the U.S. general population of major birth defects is 2% to 4%, and of miscarriage is 15% to 20%, of clinically recognized pregnancies.

Clinical Considerations
Hyaluronidase has been used as a component to aid the in vitro fertilization of human eggs. Administration of hyaluronidase during labor was reported to cause no complications: no increase in blood loss or differences in cervical trauma were observed.

Risk Summary
There is no information regarding the presence of Amphadase^® in human milk, the effects on breastfed infants, or the effects on milk production to inform risk of Amphadase^® to an infant during lactation. The developmental and health benefits of breastfeeding should be considered, along with the mother’s clinical need for Amphadase^®, and any potential adverse effects on the breastfed infant from Amphadase^®.

The safety and effectiveness of Amphadase^® have been established in pediatric patients. Use of Amphadase^® in these patients is supported by evidence from adequate and well-controlled studies. Clinical hydration requirements for children can be achieved through administration of subcutaneous fluids facilitated with Amphadase^®.

The dosage of subcutaneous fluids administered is dependent upon the age, weight, and clinical condition of the patient as well as laboratory determinations. The potential for chemical or physical incompatibilities should be kept in mind [see  Drug Interactions (7)].

The rate and volume of subcutaneous fluid administration should not exceed those employed for intravenous infusion. For premature infants or during the neonatal period, the daily dosage should not exceed 25 mL/kg of body weight, and the rate of administration should not be greater than 2 mL per minute.

During subcutaneous fluid administration, special care must be taken in pediatric patients to avoid over hydration by controlling the rate and total volume of the infusion [see  Dosage and Administration (2.1)].

No overall differences in safety or effectiveness have been observed between elderly and younger adult patients.

Hyaluronidase is a dispersion agent, which modifies the permeability of connective tissue through the hydrolysis of hyaluronic acid, a polysaccharide found in the intercellular ground substance of connective tissue, and of certain specialized tissues, such as the umbilical cord and vitreous humor. Hyaluronic acid is also present in the capsules of type A and C hemolytic streptococci.

Hyaluronidase hydrolyzes hyaluronic acid by splitting the glucosaminidic bond between C₁ of an N-acetylglucosamine moiety and C₄ of a glucuronic acid moiety. This temporarily decreases the viscosity of the cellular cement and promotes dispersion of injected fluids or of localized transudates or exudates, thus facilitating their absorption.

Hyaluronidase cleaves glycosidic bonds of hyaluronic acid and, to a variable degree, some other acid mucopolysaccharides of the connective tissue. The activity is measured in vitro by monitoring the decrease in the amount of an insoluble serum albumin-hyaluronic acid complex as the enzyme cleaves the hyaluronic acid component.

In the absence of hyaluronidase, material injected subcutaneously disperses very slowly.

Hyaluronidase facilitates dispersion, provided local interstitial pressure is adequate to furnish the necessary mechanical impulse. Such an impulse is normally initiated by injected solutions. The rate and extent of dispersion and absorption is proportionate to the amount of hyaluronidase and the volume of solution.

Results from an experimental study, in humans, on the influence of hyaluronidase in bone repair support the conclusion that this enzyme alone, in the usual clinical dosage, does not deter bone healing.

Knowledge of the mechanisms involved in the disappearance of injected hyaluronidase is limited. It is known, however, that the blood of a number of mammalian species brings about the inactivation of hyaluronidase.

Studies have demonstrated that hyaluronidase is antigenic: repeated injections of relatively large amounts of this enzyme may result in the formation of neutralizing antibodies.

Long-term animal studies have not been performed to assess the carcinogenic or mutagenic potential of hyaluronidase. Hyaluronidase is found in most tissues of the body.

Adequate fertility studies have not been conducted in animals, however, it has been reported that testicular degeneration may occur from the production of organ-specific antibodies against this enzyme following repeated injections.