Disposition of an immunoglobulin intravenous preparation in very low birth weight neonates

A Simple Method for the Prediction of Therapeutic Proteins (Monoclonal and Polyclonal Antibodies and Non-Antibody Proteins) for First-in-Pediatric Dose Selection: Application of Salisbury Rule

In order to conduct a pediatric clinical trial, it is important to optimize pediatric dose as accurately as possible. In this study, a simple weight-based method known as ‘Salisbury Rule’ was used to predict pediatric dose for therapeutic proteins and was then compared with the observed pediatric dose. The observed dose was obtained mainly from the FDA package insert and if dosing information was not available from the FDA package insert then the observed dose was based on the dose given to an age group in a particular study. It was noted that the recommended doses of most of the therapeutic proteins were extrapolated to pediatrics from adult dose based on per kilogram (kg) body weight basis. Since it is widely believed that pediatric dose should be selected based on the pediatric clearance (CL), a CL based pediatric dose was projected from the following equation: Dose in children = Adult dose × (Observed CL in children/Observed adult CL). In this study, this dose was also considered observed pediatric dose for comparison. A ±30% prediction error (predicted vs. observed) was considered acceptable. There were 21 monoclonal antibodies, 5 polyclonal antibodies in children ≥ 2 years of age, 4 polyclonal antibodies in preterm and term neonates, and 11 therapeutic proteins (non-antibodies) in the study. In children < 30 kg body weight, the predicted doses were within 0.5−1.5-fold prediction error for 87% (monoclonal antibody), 100% (polyclonal antibody), and 92% (non-antibodies) observations. In children > 30 kg body weight, the predicted doses were within 0.5−1.5-fold prediction error for 96% (monoclonal antibody), 100% (polyclonal antibody), and 100% (non-antibodies) observations. The Salisbury Rule mimics more to CL-based dose rather than per kg body weight-based extrapolated dose from adults. The Salisbury Rule for the pediatric dose prediction can be used to select first-in-children dose in pediatric clinical trials and may be in clinical settings.

A systematic review of population pharmacokinetic analyses of polyclonal immunoglobulin G therapy

BACKGROUND

Population pharmacokinetics (popPK) using the nonlinear mixed-effect (NLME) modeling approach is an essential tool for guiding dose individualization. Several popPK analyses using the NLME have been conducted to characterize the pharmacokinetics of immunoglobulin G (IgG).

OBJECTIVE

To summarize the current information on popPK of polyclonal IgG therapy.

METHOD

A systematic search was conducted in the PubMed and Web of Science databases from inception to December 2020. Additional relevant studies were also included by reviewing the reference list of the reviewed articles. All popPK studies that employed the NLME modeling approach were included and data were synthesized descriptively.

RESULTS

This review included seven studies. Most of the popPK models were developed in patients with primary immunodeficiency (PID). IgG pharmacokinetics was described as a two-compartment model in five studies, while it was described as a one-compartment model in two other studies. Among all tested covariates, weight was consistently identified as a significant predictor for clearance (CL) of IgG. Whereas, weight and disease type were found to be significant predictors for the volume of distribution in central compartment (Vc). In a typical 70 kg adult, the median estimated values of Vc and CL were 4.04 L and 0.144 L/day, respectively. The between subject variability of Vc was considered large. Only two studies evaluated their models using external data.

CONCLUSIONS

Seven popPK studies of IgG were found and discussed, with only weight being a significant covariate across all studies. Future studies linking pharmacokinetics with pharmacodynamics in PID and other patient populations are required.

Considerations for Optimizing Dosing of Immunoglobulins Based on Pharmacokinetic Evidence

Immunoglobulins (IGs) are widely used for the treatment of immunodeficiency syndromes and several autoimmune diseases. In neonates, IGs have been used for the treatment of alloimmune thrombocytopenia, in neonatal infections and in the rare cases of neonatal Kawasaki disease. This review aims to examine the various dosing regimens of IGs following intravenous (IV) and subcutaneous (SC) administration, pharmacokinetics (PK) of IGs, and the importance of trough values for the prevention of infections in patients with primary immune deficiency (PID). The review also focuses on the mechanism of catabolism of IGs and the impact on the half-life of IGs. Data and reviews were obtained from the literature and the FDA package inserts. The authors suggest that for dosing, the PK of IGs should be evaluated on the baseline-corrected concentrations since this approach provides an accurate estimate of half-life and clearance of IGs. We also suggest employing clearance as a primary PK parameter for dosing determination of IGs. We suggest that IV dosing would be more effective if given more frequently to adjust for the increased clearance at high doses and because the baseline-corrected half-life is much shorter than the baseline-uncorrected half-life. Regarding SC administration, the dose should be adjusted based on the absolute bioavailability (determined against IV dosing) of the product. Finally, we highlight clinical and PK data gaps for optimum and individualized dosing of IGs.

Considerations for pharmacokinetic assessment of immunoglobulins: Gammagard in very low birth weight neonates with and without baseline-correction

BACKGROUND

Immunoglobulins are widely used across multiple therapeutic areas such as immunodeficiency syndromes, infection and autoimmune diseases. The pharmacokinetics (PK) of immunoglobulins are well characterized in adults, but very little is known about the PK of immunoglobulins in neonates and infants.

OBJECTIVE

The objective of the present study was to characterize the PK of Gammagard, an immunoglobulin, in very low birth weight preterm neonates.

METHOD

Gammagard concentration-time data from very low birth weight neonates (bodyweight range 0.78-1.38 kg, n = 20) following intravenous administration of 500 mg/kg and 750 mg/kg were obtained from the literature. The data were analyzed with and without baseline correction using extensive blood samples (8 blood samples). Model-independent (non-compartmental) analysis was used to characterize the PK of Gammagard.

RESULTS

Based on uncorrected baseline concentration-time data, the clearance and half-life of Gammagard were 3.1 ± 0.7 mL/day and 22 ± 6 days, respectively. Based on corrected baseline concentration-time data, the clearance and half-life of Gammagard were 20.2 ± 7.4 mL/day and 5.3 ± 2.2 days, respectively.

CONCLUSION

The dose of immunoglobulins should be adjusted based on the PK of baseline corrected rather than baseline uncorrected profiles because baseline corrected PK parameters especially half-life reconciles with PK principles.

Pharmacokinetic modeling of therapies for systemic lupus erythematosus

With the increasing use of different types of therapies in treating autoimmune diseases such as systemic lupus erythematosus (SLE), there is a need to utilize pharmacokinetic (PK) strategies to optimize the clinical outcome of these treatments. Various PK analysis approaches, including population PK modeling and physiologically based PK modeling, have been used to evaluate drug PK characteristics and population variability or to predict drug PK profiles in a mechanistic manner. This review outlines the PK modeling of major SLE therapies including immunosuppressants (methotrexate, azathioprine, mycophenolate and cyclophosphamide, among others) and immunomodulators (intravenous immunoglobulin). It summarizes the population PK modeling, physiologically based PK modeling and model-based individualized dosing strategies to improve the therapeutic outcomes in SLE patients.

Pharmacokinetics of immunoglobulin administered via intravenous or subcutaneous routes

This article reviews pharmacokinetic studies of IgG administration by intravenous and subcutaneous routes. Intravenous immunoglobulin pharmacokinetics have been studied during replacement therapy for primary and secondary immunodeficiencies and other special circumstances (eg, infection prophylaxis in neonates). Subcutaneous immunoglobulin pharmacokinetics have been studied only during replacement therapy for primary immunodeficiency. Published studies vary greatly with respect to the nature of the patients studied, dose regimens, sampling schedules, and pharmacokinetic models, making comparisons difficult. With either route of administration, there is large variation in individual IgG elimination rates. Periodic measurement of serum IgG concentration is critical to monitor the adequacy of replacement during therapy.

Pharmacokinetics of Intravenous Immunoglobulin: A Systematic Review

BACKGROUND

Intravenous immunoglobulin (IGIV) is used in the treatment of a wide variety of immune disorders. To our knowledge, no comprehensive or systematic review on the pharmacokinetics of IGIV has been published despite the availability of many published individual studies.

OBJECTIVE

To systematically review published studies of the pharmacokinetics of IGIV.

METHODOLOGY

We conducted a search of PubMed/MEDLINE from January 1966-September 2005 and EMBASE from January 1980-September 2005 for English-language articles on the pharmacokinetics of IGIV. This search was supplemented by a bibliographic review of all relevant articles.

RESULTS

Data elements extracted from these articles included study design, number of study subjects, indication for IGIV therapy, IGIV treatment regimen (formulation, dosage, and duration), pharmacokinetic parameters (clearance, volume of distribution, elimination rate constant, and half-life), analytic methodology, pharmacokinetic model, and blood sampling times. The United States Preventive Services Task Force rating scale was used to categorize the 50 pertinent citations identified in our literature search. According to the rating scale, 12 studies were level I (prospective, randomized, controlled studies), 3 were level II-1 (prospective, nonrandomized, controlled studies), 30 were level II-2 (prospective, nonrandomized, uncontrolled [cohort] studies), and 5 were level III (case reports or descriptive studies).

CONCLUSION

The pharmacokinetics of IGIV shows considerable intra- and interpopulation variability among patients with normal immunoglobulin levels, patients with primary immunodeficiency diseases, bone marrow transplant recipients, patients with immune deficiency due to chronic lymphocytic leukemia or multiple myeloma, very low birth weight neonates, neonates with suspected sepsis, high-risk infants in the neonatal intensive care unit, high-risk infants with cardiopulmonary disease, children with cryptogenic West or Lennox-Gastaut syndrome, women and infants with fetal alloimmune thrombocytopenia, and women with recurrent spontaneous abortions. Despite the large number of studies characterizing the pharmacokinetics of IGIV, major literature gaps include lack of information on IGIV clearance or area under the curve parameters and target serum immunoglobulin G concentrations. Further study is needed to rigorously characterize the pharmacokinetic properties of IGIV in a range of patient populations.

Fibronectin Enhances In Vitro Lipopolysaccharide Priming of Polymorphonuclear Leukocytes

We investigated the role of humoral factors in lipopolysaccharide (LPS) priming of polymorphonuclear leukocytes (PMN) using cells isolated from adults and from neonates. Plasma from newborn infants had decreased priming activity of adult plasma when mixed with LPS in studies measuring oxidative radical production of PMN after stimulation with a formyl bacterial oligopeptide (fMLP). This marked difference was not caused by LPS binding protein (LBP) because the LBP concentration in newborn and adult plasma were similar (138.4 ± 12.9 U for adults, and 126.9 ± 12.1 U for neonates, P = .53). Therefore, we attempted to identify other plasma factors that may contribute to LPS priming of PMN. We identified an LPS priming factor for PMN that is present in plasma, heat stable (56°C for 30 minutes), enhanced by heparin, and concentrated in cold precipitates of plasma. Because these properties resemble those of plasma fibronectin, we assessed the role of fibronectin in LPS priming of PMN. Although fibronectin in phosphate-buffered saline (PBS) had little effect on LPS priming of PMN, fibronectin in combination with other plasma factors appeared to play a role in LPS priming of PMN because (1) removing fibronectin from adult plasma dramatically decreased LPS priming activity from plasma (P < .005), (2) addition of fibronectin to fibronectin-depleted plasma restored its LPS plasma priming activity (P < .05), and (3) neutralizing fibronectin with antibody decreased the LPS priming activity of plasma (60.3 ± 1.3 v 30.2 ± 2.2, P < .01). Thus, plasma fibronectin plays a role in LPS priming of PMN in the presence of other factors in plasma.

Dose-related protective efficacy of immunoglobulins in experimentally induced group B streptococcal infection

This study investigates the dose-dependent effect of administration of commercially available intravenous immunoglobulins (IVIG) on the survival of newborn rats experimentally infected with group B streptococci (GBS). The opsonic activity of various concentrations of IVIG in vitro was determined by examination of opsonophagocytosis of GBS by peritoneal macrophages and bacterial killing by blood neutrophils. The best survival was observed in newborn rats who received immunoglobulins at doses of 250, 500 and 1,000 mg/kg of bodyweight. The survival of animals that received either 125 mg/kg or 2.5 g/kg of immunoglobulins was no better than that of animals who received no immunoglobulins. The maximal phagocytosis and bacterial killing were observed at in vitro immunoglobulin concentrations ranging from 32 to 250 mg/dL (these in vitro concentrations may correspond roughly to in vivo administration doses ranging from 150 to 1200 mg/kg). These doses are comparable to the doses of IVIG currently administered to neonates. However use of very high doses may be harmful to babies since the high concentration of non-specific immunoglobulins inhibited in vitro phagocytosis and bacterial killing by phagocytes.

Intravenous immune globulin for the prevention of nosocomial infection in low-birth-weight neonates. The Multicenter Group for the Study of Immune Globulin in Neonates

BACKGROUND

Nosocomial infection is a major risk for premature infants with very low birth weights. One reason for their susceptibility to infection may be antibody deficiency, since there is little transfer of maternal IgG to the fetus before 32 weeks' gestation.

METHODS

We conducted a multicenter, double-blind study of neonates weighing 500 to 1750 g at birth. A total of 588 neonates were randomly assigned, with stratification for birth weight, to receive periodic intravenous infusions of either immune globulin (500 mg per kilogram of body weight per day) or a placebo. Mortality, morbidity, and nosocomial infection during the next 56 days were assessed.

RESULTS

The infusions were well tolerated; mild, reversible adverse reactions occurred in five infants in each group. There was a significant reduction in the risk of a first nosocomial infection in the recipients of immune globulin as compared with the placebo recipients (relative risk, 0.7; 95 percent confidence interval, 0.5 to 0.9). About 85 percent of the nosocomial infections were bacterial; the majority of these were caused by coagulase-negative staphylococci or Staphylococcus aureus. The neonates who received immune globulin had fewer mean days of hospitalization than the controls (62 vs. 68, P = 0.15); among the infants with infections, the difference in the mean length of the hospital stay was even greater (80 days vs. 101 days, P = 0.02).

CONCLUSIONS

For premature infants weighing between 500 and 1750 g at birth, treatment with intravenous infusions of immune globulin is safe and reduces the risk of nosocomial infection.

Use of intravenous gamma globulin to passively immunize high-risk children against respiratory syncytial virus: safety and pharmacokinetics. The RSVIG Study Group

Infants with cardiopulmonary disease develop severe illness from respiratory syncytial virus (RSV) infection. Safety, feasibility, and pharmacokinetics of intravenous gamma globulin (IVIG) to prevent RSV illness were studied in 23 high-risk infants in a phase I trial. IVIG with an RSV neutralizing antibody titer of 1:1,100 in 5% solution was given monthly over a 2- to 4-h period in a clinical setting during the RSV season. The first group (n = 7) received 500 mg/kg of body weight, the second group (n = 9) received 600 mg/kg, and the third group (n =7) received 750 mg/kg. Serum was drawn prior to infusion and 2, 14, and 30 days after infusion. Total immunoglobulin G and RSV A2 and RSV B neutralizing antibody levels were obtained after the first IVIG infusion. Two children developed mild reversible pulmonary edema (group receiving 600 mg/kg per dose), and one developed hives and wheezing during one infusion (group receiving 500 mg/kg per dose). Twelve children developed subsequent RSV infection during two RSV seasons (November to April) over a 2-year follow-up period; 9 of 12 developed infection during the infusion year. Eleven illnesses were mild; one child died of progressive RSV illness (group receiving 500 mg/kg per dose). A cumulative infusion effect was not observed. IVIG appears safe and feasible in an outpatient setting, and at 750 mg/kg per dose, a target RSV antibody level of greater than or equal to 1:100 was achieved.

Use of intravenous immune globulin therapy: an overview

The intravenous immune globulin (IGIV) preparations are reviewed with respect to method of preparation, pharmacokinetics, clinical uses (with emphasis on the labeled indications), and adverse reactions; a brief review of the immune system also is provided. IGIV preparations are approved for the treatment of hypogammaglobulinemia, recurrent bacterial infections due to B-cell chronic lymphocytic leukemia, and idiopathic thrombocytopenic purpura (ITP). The mechanism of action in the first two indications is passive replacement of antibodies, but in ITP the mechanism is not clearly established. The clinical literature on the use of IGIV for these indications is summarized. In patients with ITP, platelet counts return to safe levels and the number of infections is reduced in patients with primary humoral immunodeficiency treated with IGIV. The use of IGIV in pregnant women and premature infants is controversial. Adverse reactions are primarily related to infusion rate, activation of complement, and anaphylactic reactions to a component of the product. There is minimal to no risk of viral transmission with IGIV therapy. IGIV also has been administered safely on an outpatient or homecare basis. This has led to a feeling of greater control by patients over their chronic illness. Other uses of IGIV are under investigation. As our understanding of the immune system and the pharmacology of immune globulin increases, the uses of IGIV will expand.

Effect on neutrophil kinetics and serum opsonic capacity of intravenous administration of immune globulin to neonates with clinical signs of early-onset sepsis

This study was designed to test the hypothesis that administration of immune globulin to human neonates with early-onset bacterial sepsis would (1) facilitate neutrophil egress from the marrow, (2) improve serum opsonic capacity, and (3) facilitate recovery from the infectious illness. Twenty-two newborn infants with clinical signs of early-onset sepsis were given an intravenous infusion of either 750 mg of immune globulin (IVIG) per kilogram of body weight or the same volume of a vehicle control (albumin). All 22 infants survived, but significant hematologic, immunologic, and respiratory differences were observed after the IVIG and not after the control infusion. Eleven of the patients had neutropenia; 24 hours after the infusions, the neutropenia had resolved in all six IVIG recipients but persisted in all five control recipients (p less than 0.001). Ten patients had I/T neutrophil ratios (a measure of immature neutrophils to total neutrophils on the leukocyte differential count) of less than 0.2. One hour after completion of the infusions, all five IVIG recipients had elevated I/T ratios (mean +/- SEM:0.10 +/- 0.05 before vs 0.43 +/- 0.03 after infusion; p less than 0.001), suggesting a prompt release of neutrophils from the marrow neutrophil storage pool into the circulation; no increase in the I/T ratio was observed in the control recipients. Six hours after the IVIG infusions, the ratio of arterial oxygen tension to fraction of inspired oxygen increased; no increase was observed after control infusions. Serum concentrations of IgG, IgG1, IgG2, IgG3, IgG4, and total hemolytic complement and the capacity of serum to support opsonophagocytosis of type II and type III group B streptococci increased markedly in the IVIG recipients but not in the control subjects. We conclude that administration of 750 mg IVIG per kilogram to neonates with clinical signs of early-onset sepsis was associated with immunologic, hematologic, and physiologic improvement.

Prophylactic intravenous immunoglobulin in pre-term infants: a controlled trial

Sixty-six pre-term infants of less than 30 weeks gestation consecutively admitted to either of two neonatal intensive care units were randomized to receive routine intensive care only or prophylactic intravenous immunoglobulin, 200 mg/kg body weight at 3-weekly intervals in addition to routine intensive care. Eleven babies, 6 in the control group and 5 in the treatment group, were withdrawn from the trial due to early death from extreme prematurity (7 babies), early return to the referring hospital (3 babies), and elective treatment with intravenous immunoglobulin for severe congenital septicaemia (1 baby). Of the 55 who remained in the trial, significantly fewer babies in the treatment group had infection, 8 compared to 17 (p = 0.01). This difference was not significant when blood-culture-proven septicaemia only was considered, 8 compared to 14 (p = 0.09). Twenty-seven (84%) of 32 blood-culture-positive episodes of infection were caused by coagulase-negative staphylococci. Serum IgG was significantly higher with treatment and achieved levels comparable to those of normal full-term babies at the same post-natal age.

Pharmacokinetics of intravenous immunoglobulin in neonates

Intravenous immunoglobulin (IVIG) may be a therapeutic adjunct to antibiotic treatment of neonatal infections. We examined the pharmacokinetics and safety of IVIG in human neonates. Thirty neonates with suspected sepsis were randomly assigned either to a treatment (receiving either 250, 500, or 1,000 mg/kg of IVIG plus antibiotics) or control (antibiotics alone) group. The 500 mg/kg dose produced a rise in total IgG for greater than 8 and in group B streptococcus (GBS) type-specific IgG for greater than 4-14 days. The type-specific antibody elevation varied with the amount of pathogen-specific antibody and dose of IVIG. Pharmacokinetic analysis suggests a Vdss of 42 ml/kg, Cl of 3.0 ml/kg/day, a biphasic elimination curve, and a terminal elimination half-life of 24.2 days. No toxicity was observed. These data may be valuable in determining optimal dosing schedules for IVIG in treating or preventing neonatal infections.

High intravenous doses of human immune globulin suppress neonatal group B streptococcal immunity in rats

We evaluated the effect of intravenously administered immune globulin (IVIG) on neonatal group B streptococcal (GBS) infection in vivo and in vitro. A suckling rat model was used to compare the impact of penicillin (150 mg/kg) with albumin control, high-dose IVIG (2.7 gm/kg), or low-dose IVIG (0.68 gm/kg) on survival and bacteremia. Three lots of IVIG (two standard and one hyperimmune) with varying titers of GBS type III activity were used. An opsonophagocytic assay was then employed to evaluate in vitro the effect of concentrations of penicillin (none to 2.4 micrograms/ml), IVIG (none to 20 mg/ml), organism-specific (GBS type III-specific) activity (none to 1280(-1], and quantity of organisms (10(4) to 10(6] on the killing of several strains of GBS type III. Low doses of IVIG enhanced suckling rat survival (p less than 0.0025) and bacterial clearance (p less than 0.01). High doses of IVIG did not improve survival and in fact delayed bacterial clearance (p less than 0.05) when compared with low doses. Survival and bacterial clearance increased as the GBS type III activity of the IVIG lot increased. GBS opsonophagocytosis was suppressed at all penicillin concentrations (p less than 0.01) by high levels of IVIG (20 mg/ml). High-dose IVIG suppression of GBS opsonophagocytosis decreased as type III activity of the lot increased. We speculate that high doses of nonspecific IVIG may cause blockade of neutrophil or bacterial receptors necessary for GBS immunity in neonates.