Hyaluronidase; a review of its therapeutic use in pediatrics

Effect of the Kallikrein Inhibitor Aprotinin on Myocardial Ischemia and Necrosis in Man

The effect of administration of aprotinin, a serine esterase inhibitor capable of inactivating kallikrein, on the extent and severity of acute myocardial is chemic injury and subsequent necrosis, was studied in 25 patients. Another group of 25 patients who did not receive aprotinin served as a control group. We administered 100,000 kallikrein inhibitor units (KIU) of aprotinin as a bolus dose, followed by a continuous infusion (4 ml/min) that contained 10,000 KIU/kg in 240 ml of dextrose/water solution, to all 25 patients admitted to the hospital within 30 to 60 minutes after the onset of acute myocardial ischemia.

To measure the effect of aprotinin, three parameters were studied; the sum of S-T segment elevations (ΣST), the development of Q waves, and the predic tion of infarct size by measuring the disappearance rate of creatine phosphoki nase (MB CPK isoenzyme).

The average ΣST in the treated group decreased from 40.5 ± 7.00 mv to 12.95 ± 4.60 mv (P < 0.01); in contrast the control group's ΣST did not change significantly, from 54.25 ± 8.02 to 51.7 ± 6.8. Deeper Q waves evolved in the control group compared to the treated group: ΔQ (6 hours) = 1.0 ST (15 min) + 1.19 (25 patients, r = 0.78); and in the treated group ΔQ (6 hours) = 0.66 ST (15 min) + 0.91 (25 patients, r = 0.65) (P < 0.025).

In the control group the estimated infarct size was 57.4 ± 4 CPK-gram- equivalents (CPK-g-Eq). There was significantly less damage in the treated group: 19 ± 2 CPK-g-Eq (P < 0.01). Thus we conclude that aprotinin dimin ishes myocardial damage.

Facilitated subcutaneous immunoglobulin (fSCIg) therapy--practical considerations

There is an increasing range of therapeutic options for primary antibody-deficient patients who require replacement immunoglobulin. These include intravenous immunoglobulin (IVIg), subcutaneous immunoglobulin (SCIg), rapid push SCIg and most recently recombinant human hyaluronidase-facilitated SCIg (fSCIg). Advantages of fSCIg include fewer needle punctures, longer infusion intervals and an improved adverse effect profile relative to IVIg. Limited real-life experience exists concerning the practical aspects of switching or starting patients on fSCIg. We describe the first 14 patients who have been treated with fSCIg at the Immunodeficiency Centre for Wales (ICW), representing more than 6 patient-years of experience. The regimen was well tolerated, with high levels of satisfaction and no increase in training requirement, including for a treatment-naive patient. Two patients discontinued fSCIg due to pain and swelling at the infusion site, and one paused therapy following post-infusion migraines. Ultrasound imaging of paired conventional and facilitated SCIg demonstrated clear differences in subcutaneous space distribution associated with a 10-fold increase in rate and volume delivery with fSCIg. Patient profiles for those choosing fSCIg fell into two main categories: those experiencing clinical problems with their current treatment and those seeking greater convenience and flexibility. When introducing fSCIg, consideration of the type and programming of infusion pump, needle gauge and length, infusion site, up-dosing schedule, home training and patient information are important, as these may differ from conventional SCIg. This paper provides guidance on practical aspects of the administration, training and outcomes to help inform decision-making for this new treatment modality.

Subcutaneous rehydration: updating a traditional technique

Subcutaneous (SC) rehydration therapy (SCRT), originally referred to as "hypodermoclysis," shows promise as an alternative to intravenous (IV) fluid administration for treatment of dehydration. A simple, safe, and effective technique, SCRT is indicated for treatment of mild-to-moderate dehydration. Augmentation of SCRT with administration of a recombinant human formulation of the hyaluronidase enzyme at the infusion site gives rise to SC fluid administration rates up to 5-fold faster than those achieved without the enzyme, making the technique more clinically practical. Unlike older, animal-derived forms of hyaluronidase, recombinant human hyaluronidase has a lower chance of allergic reactions with repeated dosing. Clinical trials have demonstrated that recombinant human hyaluronidase effectively and safely facilitates fluid delivery in adults and children and is well accepted by parents and clinicians. In the emergency department setting, SCRT may be an appropriate alternative to IV fluid administration in certain situations because it is less invasive and generally less painful, while still permitting administration of appropriate volumes of rehydration fluids. Subcutaneous rehydration therapy appears to be particularly useful in patients who present with mild-to-moderate dehydration and have had failed attempts at oral rehydration. The SC route also provides benefits in patients with small, collapsed, or difficult-to-visualize veins or in those who may be agitated or distressed by IV catheterization. Continued research will further clarify the role of recombinant human hyaluronidase-facilitated SCRT in the rehydration treatment algorithm.

Alternatives to intravenous rehydration in dehydrated pediatric patients with difficult venous access

Intravenous (IV) catheter placement in the pediatric patient population can be challenging. Many health care providers automatically choose IV fluid administration to treat dehydration, often not considering other routes. This article reviews the available literature on difficulties in obtaining IV access in the pediatric population and discusses alternative methods for fluid replacement, their respective advantages and disadvantages, and place in therapy.

Review of the mechanism of action and clinical efficacy of recombinant human hyaluronidase coadministration with current prandial insulin formulations

For patients with type 1 or type 2 diabetes, achieving good glycemic control is critical for successful treatment outcomes. As many patients remain unable to reach glycemic goals with currently available rapid-acting analog insulins, ultrafast insulin products are being developed that provide an even faster pharmacokinetic profile compared with current rapid prandial insulin products. The overall strategy of these ultrafast insulin products is to better mimic the normal physiologic response to insulin that occurs in healthy individuals to further improve glycemic control. Recombinant human hyaluronidase (rHuPH20) is a genetically engineered soluble hyaluronidase approved by the U.S. Food and Drug Administration as an adjuvant to increase the absorption and dispersion of other injected drugs; mammalian hyaluronidases as a class have over 6 decades of clinical use supporting the safety and/or efficacy of hyaluronidase coadministration. Clinical findings have demonstrated that coadministration of rHuPH20 with insulin or an insulin analog achieved faster systemic absorption, reduced inter- and intrapatient variability of insulin absorption, and achieved faster metabolic effects compared with injection of either insulin formulation alone. The magnitude of this acceleration is similar to the incrementally faster absorption of prandial insulin analogs as compared with regular insulin. In addition, coadministration of rHuPH20 with regular insulin or insulin analog also improved the achievement of prandial glycemic targets. Thus, rHuPH20 coadministration shows promise as a method of establishing a more rapid insulin profile to prandial insulin in patients with diabetes and has the potential to yield substantial improvements in postprandial glycemic excursion.

A systematic data review of the cost of rehydration therapy

Dehydration secondary to acute gastroenteritis is a commonly encountered condition among patients presenting to physicians' offices and hospital EDs. Treatment options consist of oral rehydration therapy (ORT), intravenous rehydration therapy (IVRT) and subcutaneous rehydration therapy (SCRT). Although most patients with dehydration can be effectively treated in an outpatient setting, hospitalization is frequently warranted, with estimated annual inpatient costs for dehydration therapy exceeding $US1 billion in the US in 1999 for elderly patients alone. Although most treatment guidelines recommend ORT as first-line treatment for mild to moderate dehydration, IVRT remains the predominant route of administration for rehydration fluids in the acute care setting in the US. To evaluate the current state of the literature examining costs associated with dehydration therapy, a systematic review of articles published on MEDLINE from 2000 to 2009 was conducted. A total of 20 reports containing pharmacoeconomic data on rehydration therapy were evaluated. Findings suggest that ORT and SCRT may be less costly than IVRT in the treatment of mild to moderate dehydration; however, variability in cost parameters examined or data collection methods described in the literature precluded a comprehensive comparative cost-effectiveness analysis of treatment options. Future pharmacoeconomic analyses of rehydration therapy should incorporate time-motion analyses comprising a consistent set of variables to determine the most cost-effective treatment modality for patients with mild to moderate dehydration.

Recombinant human hyaluronidase-enabled subcutaneous pediatric rehydration

OBJECTIVES

The Increased Flow Utilizing Subcutaneously-Enabled (INFUSE)-Pediatric Rehydration Study was designed to assess efficacy, safety, and clinical utility of recombinant human hyaluronidase (rHuPH20)-facilitated subcutaneous rehydration in children 2 months to 10 years of age.

METHODS

Patients with mild/moderate dehydration requiring parenteral treatment in US emergency departments were eligible for this phase IV, multicenter, single-arm study. They received subcutaneous injection of 1 mL rHuPH20 (150 U), followed by subcutaneous infusion of 20 mL/kg isotonic fluid over the first hour. Subcutaneous rehydration was continued as needed for up to 72 hours. Rehydration was deemed successful if it was attributed by the investigator primarily to subcutaneous fluid infusion and the child was discharged without requiring an alternative method of rehydration.

RESULTS

Efficacy was evaluated in 51 patients (mean age: 1.9 years; mean weight: 11.2 kg). Initial subcutaneous catheter placement was achieved with 1 attempt for 46/51 (90.2%) of patients. Rehydration was successful for 43/51 (84.3%) of patients. Five patients (9.8%) were hospitalized but deemed to be rehydrated primarily through subcutaneous therapy, for a total of 48/51 (94.1%) of patients. No treatment-related systemic adverse events were reported, but 1 serious adverse event occurred (cellulitis at infusion site). Investigators found the procedure easy to perform for 96% of patients (49/51 patients), and 90% of parents (43/48 parents) were satisfied or very satisfied.

CONCLUSIONS

rHuPH20-facilitated subcutaneous hydration seems to be safe and effective for young children with mild/moderate dehydration. Subcutaneous access is achieved easily, and the procedure is well accepted by clinicians and parents.

Understanding clinical dehydration and its treatment

Dehydration in clinical practice, as opposed to a physiological definition, refers to the loss of body water, with or without salt, at a rate greater than the body can replace it. We argue that the clinical definition for dehydration, ie, loss of total body water, addresses the medical needs of the patient most effectively. There are 2 types of dehydration, namely water loss dehydration (hyperosmolar, due either to increased sodium or glucose) and salt and water loss dehydration (hyponatremia). The diagnosis requires an appraisal of the patient and laboratory testing, clinical assessment, and knowledge of the patient's history. Long-term care facilities are reluctant to have practitioners make a diagnosis, in part because dehydration is a sentinel event thought to reflect poor care. Facilities should have an interdisciplinary educational focus on the prevention of dehydration in view of the poor outcomes associated with its development. We also argue that dehydration is rarely due to neglect from formal or informal caregivers, but rather results from a combination of physiological and disease processes. With the availability of recombinant hyaluronidase, subcutaneous infusion of fluids (hypodermoclysis) provides a better opportunity to treat mild to moderate dehydration in the nursing home and at home.

Initial Experiences with Subcutaneous Recombinant Human Hyaluronidase

We report here our retrospective observations on the use of recombinant human hyaluronidase (rHuPH20) for the facilitation of subcutaneous hydration and drug infusion. Thirty-two patients were treated with rHuPH20 in a hospice setting over a 6-month period. Of these, 26 received this agent to enhance hypodermoclysis with standard hydration fluids for symptom control of delirium, myoclonus and mild to moderate dehydration. Flow rates up to 500 mL/hr were attained without difficulty. Electrolyte replacement in hydration fluid was achieved without incident in 5 patients receiving potassium and in 1 patient receiving both potassium and magnesium. In addition to use for hydration, 6 patients received recombinant human hyaluronidase to enhance subcutaneous infusion of 9 medications, primarily because the medication dosage required subcutaneous flow rates greater than the standard 3 mL/hr. There were no significant adverse events. Induration at the infusion site occurred in 1 patient receiving hydration and higher than expected serum lidocaine concentration was observed in another patient. Based on our positive initial experience with recombinant human hyaluronidase, there is interest in expanding its use in our facility in both the inpatient and outpatient settings.

Hyaluronidase in the prevention of sclerotherapy-induced extravasation necrosis. A dose-response study

BACKGROUND

A previous study found hyaluronidase to be effective in the prevention of necrosis following intradermal sodium tetradecyl sulfate and 23.4% sodium chloride. There are no published dose-response studies of hyaluronidase used in this manner.

OBJECTIVE

To conduct a dose-response study using hyaluronidase in the prevention of necrosis following intradermal 23.4% sodium chloride.

METHODS

Study I evaluated control vs hyaluronidase groups (150, 300, 450 units; all in volume of 3 mL) in the prevention of necrosis following intradermal 0.25 mL 23.4% sodium chloride. Incidence and size of necrosis were compared between groups. In study II, hyaluronidase was administered in doses ranging from 18.75 to 900 units (all in volume of 3 mL) immediately following the intradermal instillation of 0.25 mL of 23.4% sodium chloride. A control group had no therapy. The incidence of necrosis was compared between groups. A dose-response curve was constructed. Both studies were randomized and blinded and used Sprague-Dawley rats.

RESULTS

A statistically significant protective effect was found in the treated vs the untreated groups in both studies. Maximal protection was achieved by 75 units of hyaluronidase and was not improved upon by higher doses.

CONCLUSION

In the event of extravasation with 23.4% sodium chloride, in the model studied, one can expect maximal protection with a dose of 75 units of hyaluronidase.

Cutaneous necrosis, telangiectatic matting, and hyperpigmentation following sclerotherapy. Etiology, prevention, and treatment

BACKGROUND

Telangiectatic matting and hyperpigmentation are some of the most commonly observed side effects of sclerotherapy. Cutaneous necrosis is relatively rare and often of limited sequelae but most commonly related to extravasation of sclerosant. Physicians treating varicosities and telangiectasia by sclerotherapy must be familiar with causes and means for minimization of all three side effects.

OBJECTIVE

This review article discusses the proposed etiology, risk factors, approach for minimizing, and suggested treatment for the three side effects of cutaneous necrosis, telangiectatic matting, and hyperpigmentation.

RESULTS

Cutaneous necrosis may occur with the injection of any sclerosing agent even under ideal circumstances and does not necessarily represent physician error. When sclerosant extravasation occurs, dilution must occur immediately. Telangiectatic matting is a recognized complication occurring in approximately 15-20% of patients treated by sclerotherapy. Although the exact mechanism of the phenomena remains unknown, reactive inflammatory and/or angiogenic mechanisms are felt to play a role. Patients are advised that telangiectatic matting is usually not permanent and usually resolves spontaneously in 3-12 months. Postsclerosis pigmentation is defined as the appearance of persistent, increased pigmentation running the course of an ectatic blood vessel treated by sclerotherapy. The general incidence of hyperpigmentation ranges from 10 to 30%. Although hyperpigmentation may persist for months, its presence rarely deters patients from continuing treatment. Spontaneous resolution occurs in 70% at 6 months with 99% resolution occurring within 1 year.

CONCLUSIONS

With understanding the etiology, risk factors, and ways to minimize these side effects our goal is to reduce their incidence. Attempting prevention may ultimately be the most effective means of treatment. Dermatol Surg 1995;21:19-29.

LEARNING OBJECTIVES

After studying the following article, participant should be able to: 1. Understand the definition and potential causes of cutaneous necrosis, telangiectatic matting, and hyperpigmentation following sclerotherapy. 2. Advise patients prior to treatment on the common risks involved in sclerotherapy and to advise them on the relative incidence. 3. Understand the concept of minimal sclerosant concentration and how it can help the physician to choose sclerosing solution concentrations to minimize risks.

The prevention of cutaneous necrosis following extravasation of hypertonic saline and sodium tetradecyl sulfate

BACKGROUND

Most authors have recommended treating extravasation during sclerotherapy by infiltrating the area with 0.9% sodium chloride and/or procaine.

OBJECTIVE

To evaluate interventions in the prevention of necrosis following intradermal injection of 23.4% sodium chloride and 3% sodium tetradecyl sulfate.

METHODS

Following intradermal 23.4% sodium chloride (Study I) or 3% sodium tetradecyl sulfate (Study II), subjects (Sprague-Dawley rats) received either no treatment or injections of 0.9% sodium chloride, sterile water, 1% procaine, or hyaluronidase. Groups were compared regarding incidence and size of necrosis.

RESULTS

In study I, hyaluronidase treated groups had significantly fewer and smaller areas of necrosis than other groups. In study II, the hyaluronidase group developed significantly fewer ulcers than the 0.9% sodium chloride group. The 0.9% sodium chloride group had significantly larger ulcers than other groups.

CONCLUSION

In the model studied, hyaluronidase was the only effective treatment in the prevention of necrosis. Following 3% sodium tetradecyl sulfate, 0.9% sodium chloride was associated with larger ulcers than other groups.

Importance of the source of hyaluronidase preparations in determining protective effect on ischemic heart muscle in acute myocardial infarction

Using a very sensitive new technique, the effectiveness of hyaluronidase (HYL) in reducing infarct size (IS) was compared employing HYL obtained from bovine testicles and from fungi. One minute after coronary artery occlusion in dogs, highly radioactive microspheres were injected for autoradiographic assessment. The animals were then randomized into a control group and several HYL-treated groups. Six hours later all hearts were divided into 20 to 25, 3 mm-thick slices which were incubated in TTC to measure IS and thereafter autoradiographed to delineate the hypoperfused zone (HZ). The percent of HZ that evolved to necrosis (IS/HZ) was determined in each animal. In the control group, IS/HZ was 89.9 +/- 4.2% and was reduced by 17% (p less than 0.05) in the group treated with 500 units/kg of bovine HYL. With 500 units/kg of fungal HYL, IS/HZ was not reduced, but the higher dose of 5000 units/kg reduced IS/HZ by 26% (p less than 0.01). Thus dependence of HYL source is documented relative to the effectiveness of this salutary intervention for protecting ischemic heart muscle and limiting necrosis in acute myocardial infarction.

The effects of hyaluronidase on coronary blood flow following coronary artery occlusion in the dog

In an attempt to determine the mechanism by which hyaluronidase reduces myocardial injury following coronary artery occlusion, myocardial blood flow was studied in 20 open-chest dogs with occlusion of the left anterior descending coronary artery. Ten dogs served as controls, and 10 received hyaluronidase (500 NF units/kg) intravenously 20 minutes after occlusion. At 15 minutes and at 6 hours after occlusion, regional myocardial blood flow in the epicardial and endocardial halves of both ischemic and nonischemic zones were determined with radiolabeled microspheres. Mean arterial pressure, heart rate, and cardiac output were similar in the untreated and treated dogs through the 6 hours of the experiment. Moreover, regional blood flow to nonischemic myocardium (areas without epicardial S-T segment elevation 15 minutes after occlusion) was similar in the two groups 15 minutes and 6 hours after occlusion. Fifteen minutes after occlusion, the flow to the ischemic myocardium subjacent to sites with S-T segment elevation exceeding 2 mV) in the untreated group was: transmural, 28.1 +/- 2.2 (mean +/- SE) ml/min per 100 g; endocardial, 20.7 +/- 1.8; and epicardial, 38.5 +/- 3.1. The endocardial-epicardial flow ratio was 0.56 +/- 0.04. Six hours after occlusion, the untreated group demonstrated a further decrease in blood flow to the ischemic myocardium: transmural, 15.2 +/- 1.4 ml/min per 100 g; endocardial, 6.8 +/- 1.1; and epicardial, 24.3 +/- 1.9. The endocardial-epicardial flow ratio fell to 0.28 +/- 0.04. In contrast, the hyaluronidase-treated dogs showed no further reduction in blood flow to ischemic myocardium 6 hours after occlusion: transmural, 30.3 +/- 3.1 ml/min per 100 g; endocardial, 21.3 +/- 2.5; and epicardial, 38.8 +/- 3.8. These regional myocardial flows were significantly higher than those of the untreated dogs 6 hours after occlusion. Thus, salvage of damaged myocardium by hyaluronidase might be explained by its beneficial effect on collateral blood flow to the ischemic tissue, though this effect on collateral flow could be the consequence rather than the cause of this salvage.

Favorable effects of hyaluronidase on electrocardiographic evidence of necrosis in patients with acute myocardial infarction

To evaluate hyaluronidase's effect in reducing post-infarction myocardial necrosis, we randomized 91 patients with anterior infarction to control (45) or to hyaluronidase-treatment (46) groups. A 35-lead precordial electrocardiogram was recorded on admission and seven days later. Hyaluronidase was administered intravenously after the first electrocardiogram and every six hours for 48 hours. QRS-complex changes were analyzed to assess the drug's effect. Precordial sites with ST-segment elevation (larger than or equal to 0.15 mV) on the initial electrocardiogram that retained an R wave were considered vulnerable for the development of electrocardiographic signs of necrosis. The sum of R-wave voltages of vulnerable sites fell more in the control group than in the hyaluronidase group (70.9 +/- 3.6 per cent [+/- 1 S.E.M.] vs 54.2 +/- 5.0 per cent P less than 0.01). Q waves appeared in 59.3 +/- 4.9 per cent of the vulnerable sites in control versus 46.4 +/- 4.9 per cent in hyaluronidase-treated patients (P less than 0.05). Thus, hyaluronidase reduced the frequency of electrocardiographic signs of myocardial necrosis.

Effects of hyaluronidase and hydrocortisone on myocardial necrosis after coronary occlusion

In anesthetized open chest dogs, hydrocortisone (50 mg/kg body weight administered 30 minutes after occlusion and 25 mg/kg 12 hours later) substantially reduced the size of myocardial infarcts, as reflected by both myocardial creatine phosphokinase activity and histologic appearance 24 hours later. Similarly, hyaluronidase, which increases diffusion through the extracellular space and presumably facilitates delivery of substrate to ischemic cells, also reduced the extent of myocardial necrosis after coronary occlusion in the dog. In view of the salutary effects of hyaluronidase and the absence of serious side effects, this agent was administered clinically to two groups of patients, who were compared with two groups of untreated control subjects. Hyaluronidase (500 National Formulary units/kg X 8) was shown to result in a significantly more rapid reduction in the magnitude and the extent of precordial S-T segment elevations, and in patients treated within 4 hours a tendency to a lower incidence rate of Q waves and a smaller reduction of R waves.

Reduction by hyaluronidase of myocardial necrosis following coronary artery occlusion

Electrocardiographic, enzymatic, and morphologic signs of myocardial ischemic injury following coronary occlusion have previously been shown to be ameliorated by reducing myocardial oxygen requirements, and/or by increasing the availability of oxygen as well as of substrates for anaerobic ATP production. Since hyaluronidase increases diffusion through the extracellular space and may facilitate delivery of substrates to ischemic cells, the influence of its administration on the size of experimentally produced infarcts was studied. In 14 control dogs epicardial electrocardiograms were taken in 10-15 sites on the anterior surface of the left ventricle before and after occlusion of the left anterior descending coronary artery. Twenty-four hours later, transmural specimens were obtained from the same sites from which electrocardiograms had been recorded, and were analyzed for creatine phophokinase (CPK) activity, for histologic changes, and glycogen content. In control dogs, sites exhibiting S-T-segment elevation 15 min after occlusion showed early structural signs of necrosis and glycogen depletion in 97% of specimens taken after 24 hours. The relationship between S-T-segment elevation at 15 min (mv) and CPK activity 24 hours later (IU/mg protein) was log CPK = –0.061 S-T + 1.26. Hyaluronidase (225 u/kg) was given to 15 dogs; no hemodynamic changes occurred but the depression of CPK activity was reduced following occlusion; log CPK = –0.024 S-T + 1.28. Similarly, only 55% of sites that showed S-T-segment elevation prior to hyaluronidase administration exhibited histologic signs of early infarcts and glycogen depletion 24 hours later. It is concluded that hyaluronidase diminished myocardial necrosis following acute coronary occlusion.