Identification of the component part in an epoetin alfa preparation that causes pain after subcutaneous injection

New insight into the importance of formulation variables on parenteral growth hormone preparations: potential effect on the injection-site pain

Reducing injection-site pain (ISP) in patients with chronic conditions such as growth hormone deficiency is a valuable strategy to improve patient compliance and therapeutic efficiency. Thus understanding different aspects of pain induction following subcutaneous injection of biotherapeutics and identifying the responsible factors are vital. Here we have discussed the effects of formulation's viscosity, concentration, osmolality, buffering agents, pH, and temperature as well as injection volume, dosing frequency, and different excipients on ISP following subcutaneous injection of commercially available recombinant human growth hormone products. Our literature review found limited available data on the effects of different components of parenteral rhGH products on ISP. This may be due to high cost associated with conducting various clinical trials to assess each excipient in the formulation or to determine the complex interactions of different components and its impact on ISP. Recently, conducting molecular dynamics simulation studies before formulation design has been recommended as an alternative and less-expensive approach. On the other hand, the observed inconsistencies in the available data is mainly due to different pain measurement approaches used in each study. Moreover, it is difficult to translate data obtained from animal studies to human subjects. Despite all these limitations, our investigation showed that components of parenteral rhGH products can significantly contribute to ISP. We suggest further investigation is required for development of long acting, buffer-free, preservative-free formulations. Besides, various excipients are currently being investigated for reducing ISP which can be used as alternatives for common buffers, surfactants or preservatives in designing future rhGH formulations.

Multi-Electrode Array of Sensory Neurons as an In Vitro Platform to Identify the Nociceptive Response to Pharmaceutical Buffer Systems of Injectable Biologics

PURPOSE

Pharmaceutical buffer systems, especially for injectable biologics such as monoclonal antibodies, are an important component of successful FDA-approved medications. Clinical studies indicate that buffer components may be contributing factors for increased injection site pain.

METHODS

To determine the potential nociceptive effects of clinically relevant buffer systems, we developed an in vitro multi-electrode array (MEA) based recording system of rodent dorsal root ganglia (DRG) sensory neuron cell culture. This system monitors sensory neuron activity/firing as a surrogate of nociception when challenged with buffer components used in formulating monoclonal antibodies and other injectable biologics.

RESULTS

We show that citrate salt and citrate mannitol buffer systems cause an increase in mean firing rate, burst frequency, and burst duration in DRG sensory neurons, unlike histidine or saline buffer systems at the same pH value. Lowering the concentration of citrate leads to a lower firing intensity of DRG sensory neurons.

CONCLUSION

Increased activity/firing of DRG sensory neurons has been suggested as a key feature underlying nociception. Our results support the utility of an in vitro MEA assay with cultured DRG sensory neurons to probe the nociceptive potential of clinically relevant buffer components used in injectable biologics.

Subcutaneous Injection Site Pain of Formulation Matrices

PURPOSE

The objective of this work was to systematically evaluate the effects of formulation composition on subcutaneous injection site pain (ISP) using matrices comprising of common pharmaceutical excipients.

METHODS

Two randomized, blinded, crossover studies in healthy subjects were conducted at a single site, where subjects received 1 mL SC injections of the buffer matrices. ISP intensity was measured using a 100 mm visual analogue scale (VAS), which was then analyzed via heatmap, categorical grouping, subgroup analysis, and paired delta analysis.

RESULTS

Buffer type, buffer concentration and tonicity agent showed a substantial impact on ISP. Citrate buffer demonstrated a higher ISP than acetate buffer or saline). The 20 mM citrate buffer was more painful than 10 or 5 mM citrate buffers. NaCl and propylene glycol were significantly more painful than sugar alcohols (mannitol, sucrose, trehalose or glycerol). Histidine buffers exhibited ISP in the descending order of 150 mM > 75 mM > 25 mM > 0 mM NaCl, while histidine buffers containing Arginine-HCl at 0, 50, or 150 mM all showed very low ISP. Histidine buffer at pH 6.5 showed a lower ISP than pH 5.7.

CONCLUSIONS

This systematic study via orthogonal analyses demonstrated that subcutaneous ISP is significantly influenced by solution composition.

Citric Acid in Drug Formulations Causes Pain by Potentiating Acid-Sensing Ion Channel 1

Pain at the injection site is a common complaint of patients receiving therapeutic formulations containing citric acid. Despite the widely acknowledged role of acid-sensing ion channels (ASICs) in acid-related perception, the specific ASIC subtype mediating pain caused by subcutaneous acid injection and the mechanism by which citrate affects this process are less clear. Here, male mice subjected to intraplantar acid injection responded by executing a withdrawal reflex, and this response was abolished by ASIC1 but not ASIC2 knockout. Although intraplantar injection of neutral citrate solution did not produce this response, intraplantar injection of acidic citrate solution produced a withdrawal reflex greater than that produced by acidity alone. Consistent with the behavioral data, neutral citrate failed to produce an electrophysiological response in HEK293 cells, which express ASIC1, but acidic citrate produced a whole-cell inward current greater than that produced by acidity alone. Saturating the intracellular solution with citrate had no effect on the potentiating effect of extracellular citrate, suggesting that citrate acted extracellularly to potentiate ASIC1. Moreover, exposure to citrate immediately before acid stimulation failed to potentiate ASIC1 currents, which ruled out the involvement of a metabotropic receptor gated by a citrate metabolite. Finally, removal of calcium ions from the extracellular solution mimicked the potentiating effect of citrate and prevented citrate from further potentiating ASIC1. Our data demonstrate that ASIC1 is necessary for the nociceptive response caused by subcutaneous acid infusion and that neutral citrate, despite not inducing ASIC1 currents or nociceptive behavior on its own, potentiates acid nociception by removing the inhibitory effect of extracellular calcium ions on ASIC1.

SIGNIFICANCE STATEMENT Citric acid is a common ingredient used in pharmaceutical formulations. Despite the widespread clinical use of these formulations, it remains unclear how citric acid causes pain when injected into patients. We identified ASIC1 as the key receptor used to detect injection-site pain caused by acid, and we showed that neutral citrate does not stimulate ASIC1; instead, citrate substantially potentiates ASIC1 activation when injected simultaneously with acid. In addition, we demonstrated that citrate potentiates ASIC1 by removing the inhibitory action of calcium on the extracellular side of the receptor. Given that injection-site pain is the primary complaint of patients receiving citrate-containing medical products, our data provide mechanistic insight into a common medical complaint and suggest a means of avoiding injection pain.

Subcutaneous Delivery of High-Dose/Volume Biologics: Current Status and Prospect for Future Advancements

Subcutaneous (SC) delivery of biologics has traditionally been limited to fluid volumes of 1-2 mL, with recent increases to volumes of about 3 mL. This injection volume limitation poses challenges for high-dose biologics, as these formulations may also require increased solution concentration in many cases, resulting in high viscosities which can affect the stability, manufacturability, and delivery/administration of therapeutic drugs. Currently, there are technologies that can help to overcome these challenges and facilitate the delivery of larger amounts of drug through the SC route. This can be achieved either by enabling biologic molecules to be formulated or delivered as high-concentration injectables (>100 mg/mL for antibodies) or through facilitating the delivery of larger volumes of fluid (>3 mL). The SC Drug Delivery and Development Consortium, which was established in 2018, aims to identify and address critical gaps and issues in the SC delivery of high-dose/volume products to help expand this delivery landscape. Identified as a high priority out of the Consortium's eight problem statements, it highlights the need to shift perceptions of the capabilities of technologies that enable the SC delivery of large-volume (>3 mL) and/or high-dose biologics. The Consortium emphasizes a patient-focused approach towards the adoption of SC delivery of large-volume/high-concentration dosing products to facilitate the continued expansion of the capabilities of novel SC technologies. To raise awareness of the critical issues and gaps in high-dose/volume SC drug development, this review article provides a generalized overview of currently available and emerging technologies and devices that could facilitate SC delivery of high-dose/volume drug formulations. In addition, it discusses the challenges, gaps, and future outlook in high-dose/volume SC delivery as well as potential solutions to exploit the full value of the SC route of administration.

The Impact of Product and Process Related Critical Quality Attributes on Immunogenicity and Adverse Immunological Effects of Biotherapeutics

The pharmaceutical industry has experienced great successes with protein therapeutics in the last two decades and with novel modalities, including cell therapies and gene therapies, more recently. Biotherapeutics are complex in structure and present challenges for discovery, development, regulatory, and life cycle management. Biotherapeutics can interact with the immune system that may lead to undesired immunological responses, including immunogenicity, hypersensitivity reactions (HSR), injection site reactions (ISR), and others. Many product and process related critical quality attributes (CQAs) have the potential to trigger or augment such immunological responses to the product. Tremendous efforts, both clinically and preclinically, have been invested to understand the impact of product and process related CQAs on adverse immunological effects. The information and knowledge are critical for the implementation of Quality by Design (QbD), which requires risk assessment and establishment of specifications and control strategies for CQAs. A quality target product profile (QTPP) that identifies the key CQAs through process development can help assign severity scores based on safety, immunogenicity, pharmacokinetics (PK) and pharmacodynamics (PD) of the molecule. Gaps and future directions related to biotherapeutics and emerging novel modalities are presented.

Evaluation of Adherence and Persistence Differences Between Adalimumab Citrate-Free and Citrate Formulations for Patients with Immune-Mediated Diseases in the United States

INTRODUCTION

Our aim was to evaluate patient adherence and persistence with citrate-free adalimumab (ADA-CF), introduced in 2018 to reduce injection-site pain, compared with citrate-containing adalimumab (ADA-C).

METHODS

This was a retrospective cohort study using a US claims database (IBM^® MarketScan^® Commercial and Medicare Supplemental Claims Database) from February 2018 to January 2020. Patients at least 18 years of age who were naïve to adalimumab 6 months before the index date (date of first adalimumab claim) and with at least 12 months of continuous medical and pharmacy coverage were eligible for the study. Adherence was assessed by determining the proportion of days covered (PDC) and the percentage of patients with PDC ≥ 80% during the 12-month follow-up period. Persistence was evaluated by measuring the rate of discontinuation and days to discontinuation (i.e., time on treatment) from the index date over the 12-month follow-up period. Continuous adherence outcomes (PDC) were evaluated using linear regression models. Binary adherence outcomes (PDC ≥ 80%) were assessed using logistic regression models. Kaplan-Meier analysis and Cox proportional hazards models were used to assess persistence outcomes.

RESULTS

There were 2195 and 1005 patients in the ADA-CF and ADA-C cohorts, respectively, with most using adalimumab for rheumatoid arthritis (ADA-CF 29.7%, ADA-C 27.2%) and psoriasis (ADA-CF 24.5%, ADA-C 31.9%). Significantly greater adherence was achieved with ADA-CF compared with ADA-C (mean PDC [standard deviation] 0.68 [0.30] vs 0.61 [0.32], P < 0.0001). A significantly greater percentage of patients receiving ADA-CF (47.2%) vs ADA-C (39.6%) had PDC ≥ 80% (P < 0.0001). The discontinuation rate was significantly lower for the ADA-CF cohort (46.4%) compared with ADA-C (55.9%, P < 0.0001), resulting in a 27% lower likelihood of discontinuation during the 12-month follow-up period (hazard ratio 0.73; 95% confidence interval 0.66, 0.82; P < 0.0001) and longer time on treatment (260 vs 232 days, P < 0.0001).

CONCLUSION

Adherence and persistence are significantly improved with ADA-CF compared with ADA-C.

Erythropoietin Administration for Anemia Due to Chronic Kidney Disease - Subcutaneous OR Intravenous, What Do We Know So Far?

The prevalence of anemia in chronic kidney disease (CKD) patients is almost twice that of the normal population and its severity increases exponentially as the disease worsens, dramatically affecting the quality of an individual’s life. The advent of erythropoiesis stimulating agents (ESA) in the 1980s saw a revolutionary change in the treatment of anemia in CKD patients, drastically improving quality of life (QoL), overall health and reducing the need for blood transfusions. Numerous ESAs have been developed ever since and are in current use, with the primary routes of administration being intravenous (IV) and subcutaneous (SC) injections. Their use, however, has stirred significant controversy over the last two decades. Additionally, despite numerous studies and trials, the latest international recommendations for their use do not provide clear cut guidance with well-grounded evidence on the recommended route of administration for different sets of patients. Instead, this decision has mainly been left up to the physician’s discretion, whilst keeping certain key factors in mind. This review shall summarize, discuss and compare the findings of previous studies on various factors governing the two aforementioned routes of administration and identify areas that need further exploration.

Subcutaneous Injection of Drugs: Literature Review of Factors Influencing Pain Sensation at the Injection Site

The subcutaneous administration route is widely used to administer different types of drugs given its high bioavailability and rapid onset of action. However, the sensation of pain at the injection site might reduce patient adherence. Apart from a direct effect of the drug itself, several factors can influence the sensation of pain: needle features, injection site, volume injected, injection speed, osmolality, viscosity and pH of formulation, as well as the kind of excipients employed, including buffers and preservatives. Short and thin needles, conveniently lubricated and with sharp tips, are generally used to minimize pain, although the anatomic injection site (abdomen versus thigh) also affects the sensation of pain. Large subcutaneous injection volumes are associated with pain. In this sense, the maximum volume generally accepted is around 1.5 ml, although volumes of up to 3 ml are well tolerated when injected in the abdomen. Injected volumes of up to 0.5–0.8 ml are not expected to increase substantially the pain produced by the needle insertion. Ideally, injectable products should be formulated as isotonic solutions (osmolality of about 300 mOsm/kg) and no more than 600 mOs/kg have to be used in order to prevent pain. A pH close to the physiological one is recommended to minimize pain, irritation, and tissue damage. Buffers are frequently added to parenteral formulations to optimize solubility and stability by adjusting the pH; however, their strength should be kept as low as possible to avoid pain upon injection. The data available recommend the concentration of phosphate buffer be limited to 10 mM and that the concentration of citrate buffer should be lower than 7.3 mM to avoid an increased sensation of pain. In the case of preservatives, which are required in multiple-dose preparations, m-cresol seems to be more painful than benzyl alcohol and phenol.

Funding: Sandoz SA.

New adalimumab formulation associated with less injection site pain and improved motivation for treatment

Objectives: We aimed to evaluate the effect of change to the existing formulation of adalimumab (ADA) on pain and treatment motivation.Methods: We classified injection pain into the following categories: overall pain, pain at needle insertion, pain during drug injection, and pain 10 min after injection; we evaluated the effect of change to the existing formulation on pain using a visual analogue scale. In addition, a faces pain scale was used to evaluate the effect of change in injection pain intensity on treatment motivation.Results: Compared with the existing ADA formulation, the new formulation was associated with lower scores of overall pain (1.6 vs. 6.7), pain at needle insertion (1.8 vs. 4.7), pain during injection (1.6 vs. 7.0), and pain 10 min after the injection (0.4 vs. 3.1). All results showed a significant difference. p < .001. Paired t-tests were used. In the survey, 68% and 80% of the patients reported injection pain with influenza vaccine and the existing formulation, respectively; however, the proportion of the patients who experienced pain with the new formulation decreased to 20%.Conclusions: The new ADA formulation may alleviate the burden on RA patients and improve the quality of adherence to treatment, thereby influencing the RA treatment outcomes.

Pain Perception following Subcutaneous Injections of Citrate-Buffered and Phosphate-Buffered Epoetin Alpha

Subcutaneous injection of citrate-buffered epoetin alpha (EPO-α) causes pain. Substitution of citrate buffer with a phosphate buffer in the EPO-α resulted in a significant reduction in duration and severity of pain. It is possible that sodium citrate which is present in the EPO-α may be the agent that causes discomfort in the patients.

Role of Buffers in Protein Formulations

Buffers comprise an integral component of protein formulations. Not only do they function to regulate shifts in pH, they also can stabilize proteins by a variety of mechanisms. The ability of buffers to stabilize therapeutic proteins whether in liquid formulations, frozen solutions, or the solid state is highlighted in this review. Addition of buffers can result in increased conformational stability of proteins, whether by ligand binding or by an excluded solute mechanism. In addition, they can alter the colloidal stability of proteins and modulate interfacial damage. Buffers can also lead to destabilization of proteins, and the stability of buffers themselves is presented. Furthermore, the potential safety and toxicity issues of buffers are discussed, with a special emphasis on the influence of buffers on the perceived pain upon injection. Finally, the interaction of buffers with other excipients is examined.

Randomized Crossover Comparison of Injection Site Pain with 40 mg/0.4 or 0.8 mL Formulations of Adalimumab in Patients with Rheumatoid Arthritis

Introduction

Adalimumab, an anti-tumor necrosis factor antibody, is currently available in a 40 mg/0.8 mL formulation. The objective of this analysis was to evaluate injection site-related pain, safety, and tolerability of a 40 mg/0.4 mL formulation of adalimumab that had fewer excipients, a smaller volume, and a delivery presentation with a smaller gauge needle, versus the current 40 mg/0.8 mL formulation in patients with rheumatoid arthritis (RA).

Methods

Two identically designed, phase 2, randomized, single-blind, two-period crossover studies were conducted in Belgium and the Czech Republic (Study 1) and Australia, Canada, and Germany (Study 2). In both studies, adults with RA [biologic-naive or current users of 40 mg/0.8 mL adalimumab with an average injection site-related pain rating ≥3 cm on a visual analog scale (VAS; 0–10 cm)] were randomized to receive 40 mg/0.8 mL or 40 mg/0.4 mL adalimumab at visit 1. After 1–2 weeks (depending on patient medication schedule), patients received the other formulation at visit 2. A pain VAS [McGill Pain Questionnaire (MPQ-SF)] and the Draize scale were evaluated immediately after injection and 15 min postinjection. The primary endpoint was immediate pain after injection.

Results

64 and 61 patients were randomized in Studies 1 and 2, respectively. Both studies found a clinically relevant and statistically significant lower immediate pain after injection for the 40 mg/0.4 mL versus the 40 mg/0.8 mL formulation. The mean difference on the VAS for the pooled data (−2.48 cm) was also clinically relevant. Most other endpoints in both studies favored the 40 mg/0.4 mL formulation, and its tolerability and safety profile were consistent with 40 mg/0.8 mL adalimumab.

Conclusion

A 40 mg/0.4 mL adalimumab formulation was well tolerated and associated with less injection site-related pain than the 40 mg/0.8 mL adalimumab formulation.

Trial registration

ClinicalTrials.gov identifier, NCT01561313 and NCT01502423.

Funding

AbbVie.

Electronic supplementary material

The online version of this article (doi:10.1007/s40744-016-0041-3) contains supplementary material, which is available to authorized users.

Injection-site reactions upon Kineret (anakinra) administration: experiences and explanations

Anakinra (Kineret), a recombinant form of human interleukin-1 (IL-1) receptor antagonist, is approved for the treatment of rheumatoid arthritis (RA) in combination with methotrexate. Kineret is self-administered by daily subcutaneous injections in patients with active RA. The mechanism of action of anakinra is to competitively inhibit the local inflammatory effects of IL-1. Kineret is generally safe and well tolerated and the only major treatment-related side effects that appear are skin reactions at the injection site. Due to the relatively short half-life of anakinra, daily injection of the drug is required. This, in combination with the comparably high rates of injection-site reactions (ISRs) associated with the drug, can become a problem for the patient. The present review summarises published data concerning ISRs associated with Kineret and provides some explanations as to their cause. The objective is also to present some clinical experiences of how the ISRs can be managed.

Meeting New Challenges in the Management of Anemia of Chronic Kidney Disease Through Collaborative Care with Pharmacists

Objective:

To evaluate chronic kidney disease (CKD)–associated anemia management challenges and limitations and discuss strategies to improve treatment rates and patient response to therapy, monitoring of patient response to therapy, and education of prescribing providers and patients.

Data Sources:

Multiple MEDLINE searches were performed using a comprehensive search term list to identify studies for inclusion, including, but not limited to, anemia, erythropoiesis-stimulating agent (ESA), epoetin, darbepoetin, CERA, hemoglobin, CKD, dialysis, end-stage renal disease, quality of life, and pharmacist. Annual data reports and clinical practice guidelines published by the National Kidney Foundation and US Renal Data System were included. Information provided within product package inserts for recombinant human erythropoietin (epoetin alfa; Epogen, Procrit) and darbepoetin alfa (Aranesp) were also included.

Study Selection and Data Extraction:

Only articles that were published in English and were relevant for this review were included.

Data Synthesis:

Anemia is a common complication of CKD, with significant impact on patients' quality of life. Anemia of CKD represents a significant burden on the healthcare system, with ESA use resulting in substantial financial costs. As new therapies, formularies, and dosing regimens evolve, the collaborative role of the clinical pharmacist is integral to a multidisciplinary treatment strategy, both in the inpatient and outpatient settings, such as hospitals or dialysis centers, respectively. This review focuses on initial and target hemoglobin (Hb) concentrations, as well as patient characteristics, treatment preferences, and dosing schedules, which are important considerations in managing CKD-associated anemia. To ensure effective therapeutic strategies, a patient-centered approach is required. Pharmacists are ideally positioned to help select ESA therapy, influence formulary use, educate healthcare professionals and patients, develop and implement dosing and monitoring protocols, and possibly promote quality improvement.

Conclusions:

An approach to CKD-associated anemia management that involves collaboration with pharmacists is essential to achieve patient-specific, cost-effective ESA therapy.

Subcutaneous injection pain with C.E.R.A., a continuous erythropoietin receptor activator, compared with darbepoetin alfa

OBJECTIVE

This study assessed injection site pain following subcutaneous (SC) administration with a continuous erythropoietin receptor activator (C.E.R.A.), compared with darbepoetin alfa in healthy adults.

METHODS

In a randomized, placebo-controlled, single-centre, single-blind, three-way crossover study, subjects received one of six treatment sequences (ABC/ACB/BAC/BCA/CBA/CAB) involving SC injection of (A) C.E.R.A. 50 microg, (B) darbepoetin alfa 50 microg, or (C) placebo on days 1, 29, and 57. An initial pilot phase (n = 12) was used to determine the sample size for the confirmatory phase (n = 72), and data were combined for the final analysis (n = 84).

MAIN OUTCOME MEASURES

The primary endpoint was pain on the 100 mm visual analog scale (VAS) immediately after dosing. Secondary endpoints included VAS at 1 hour after dosing and pain on the six-point verbal rating scale (VRS) immediately and at 1 hour after dosing.

RESULTS

C.E.R.A. was associated with significantly less pain immediately after SC injection compared with darbepoetin alfa: least squares mean VAS 21.5 (95% confidence interval [CI]: 17.5, 25.5) versus 33.4 (95% CI: 28.4, 38.4) (p < 0.0001). Incidence of pain on the VRS was lower with C.E.R.A. compared with darbepoetin alfa immediately after dosing (p < 0.0001). One hour after administration, most subjects had no VRS pain. A study limitation is the small sample size and the findings need to be confirmed in a large trial of chronic kidney disease patients.

CONCLUSIONS

SC injection with C.E.R.A. is significantly less painful than SC darbepoetin alfa in healthy adults. Treatment of anemia in chronic kidney disease with SC injection of C.E.R.A. may provide a lower pain burden compared with darbepoetin alfa.

Nonhematologic complications of erythropoietin therapy

Exogenous recombinant human erythropoietin (rHuEPO) is a beneficial therapeutic agent for correction of anemia in both chronic kidney disease (CKD) and end-stage renal disease (ESRD) patients. Transfusion requirements in ESRD patients are reduced significantly and anemia management is much improved. Despite widespread use and near-universal exposure of ESRD patients to the drug, rHuEPO remains an effective and safe product. However, a number of nonhematologic complications are described with rHuEPO therapy. Most notable is hypertension, whereas the connection between seizure and enhanced thrombosis is less clear. A possible complication recently described is exacerbation of proliferative diabetic retinopathy. Finally, other less common adverse effects, although rare in most patients, should be recognized as such by physicians who prescribe rHuEPO.

Pain Perception after Subcutaneous Injections of Media Containing Different Buffers

Several hormones are administered by daily subcutaneous injections. Pain caused by subcutaneous injection is an unpleasant condition, which can limit patient compliance. The objective of the present study was to evaluate the perception of pain by subcutaneous injection of two different and commercially available solutions for dispensing recombinant human growth hormone. The solutions are characterised by pH, conservation, and buffer. Isotonic saline was used as reference solution. Fifty-four healthy volunteers (mean age (+/-S.E.M.): 35.5+/-1.1 years) were recruited to the double-blind, randomised study. All injections were performed pairwise (right and left thigh) in one day by the same experienced nurse. Perception of pain was evaluated by the volunteers immediately after injection and 2 min. after injection into the thigh of three formulations, which differed with respect to pH and buffers (histidine, citrate and saline, respectively). Significantly more participants (38/54) found than the citrate buffer caused more pain than the histidine buffer immediately after injection (P=0.002). Histidine buffer did not cause more pain than saline (P=0.996). After 2 min., there was no difference between the histidine and the citrate buffer (P=1.00), nor between the histidine buffer and saline (P=1.00). In summary, the solution-containing citrate as buffer caused more pain after subcutaneous injection than the solution with histidine as buffer. Considering patient compliance, it seems advisable to employ histidine-buffered solution rather than citrate-buffered solution for dispensing recombinant human growth hormone by daily subcutaneous injections.

A comparison of the bioequivalence of two formulations of epoetin alfa after subcutaneous injection

BACKGROUND

The previous formulation of epoetin alfa in Japan was a citrate-buffered protein solution containing gelatin hydrolysate as the protein protective agent. To eliminate pain at injection sites, and the risks of anaphylactic shock and unknown infections by gelatin we have developed a new formulation of phosphate-buffered epoetin alfa, which does not contain gelatin hydrolysate.

AIM

To compare the bioequivalence of two formulations of epoetin alfa administered by the subcutaneous route.

METHODS

Four separate studies were performed to assess the bioequivalence of two epoetin alfa formulations using different strength and doses, i.e. 750 IU per 0.5 ml x 0.5 ml (= 750 IU per subject), 750 IU per 0.5 ml x 4 ml (= 6000 IU per subject), 6000 IU per 0.5 ml x 0.5 ml (= 6000 IU per subject) and 24,000 IU per 0.5 ml x 0.125 ml (= 6000 IU per subject). Each study was a single-centre, open-label, randomized, two-treatment, two-period, crossover study for which healthy volunteers were enrolled. Bioequivalence was assessed using the confidence interval (CI) of the ratios for the log-transformed, baseline-corrected Cmax and AUC(0,t). Baseline-corrected AUC(0,t) was calculated using the following equation: AUC(0,t) = AUC(0,t), uncorrected -- predose level x observation period.

RESULTS

The ratios (gelatin-free/gelatin-containing) for the log-transformed Cmax and AUC(0,t) after 6000 IU per subject injection of three different concentrations of epoetin alfa were well within the usual range for bioequivalence (90% CI 0.8, 1.25). The 90% CI of the ratio for Cmax after 750 IU per subject injection was 0.906, 1.24, which was within the bioequivalence range. However, the ratio for AUC(0,t) was not determined in this lowest dose because of negative AUC(0,t) values obtained in 12/60 cases. The overall safety data were consistent with those expected for a healthy study population, and did not present any concerns suggestive of adverse effects due to either formulation.

CONCLUSIONS

The point estimates and 90% CIs of the ratios of Cmax and AUC(0,t) for the gelatin-free/gelatin-containing formulations indicated that the two formulations are bioequivalent.

Pharmacoeconomic considerations in the health system management of anaemia in patients with chronic kidney disease and end stage renal disease

Anaemia is prevalent in patients with chronic kidney disease and end stage renal disease. If left untreated, it greatly affects patient survival, quality of life and functional status. Epoetin and darbepoetin are two biotechnology drugs that effectively stimulate the production of red blood cells. These drugs have been shown to significantly increase haemoglobin concentrations and improve quality of life. So far, there have been no head-to-head pharmacoeconomic studies that have compared epoetin to darbepoetin. Health system decision makers need to evaluate important considerations when comparing these agents. These considerations include drug acquisition costs, the patient population being treated, the location of drug administration (in-patient versus ambulatory) and federal government reimbursement. This review details these important pharmacoeconomic considerations.

Epoetin alfa: current and future indications and nursing implications

Cancer-related anemia commonly is associated with fatigue and decreased quality of life (QOL). Treatment to achieve optimal hemoglobin levels in patients receiving chemotherapy can alleviate common symptoms of anemia and may allow patients to have more meaningful survival time while on chemotherapy. New studies have suggested that epoetin alfa (Procrit, Ortho Biotech Products, LP, Raritan, NJ) can be administered safely and effectively once a week in patients with anemia other than those patients with cancer receiving concomitant chemotherapy. Preclinical studies and pilot clinical studies also have suggested a new application for epoetin alfa in improving cognitive function. Oncology nurses skilled at anticipating, assessing, and managing anemia and its symptoms can be instrumental in improving the QOL of patients with cancer. They should be aware of clinical trials that have suggested advantages of improved dosing schedules and new applications for epoetin alfa.

Assessment of the myotoxicity of pharmaceutical buffers using an in vitro muscle model: effect of pH, capacity, tonicity, and buffer type

The purpose of the present study was to investigate the myotoxicity of three buffers containing carboxylic acid groups (i.e., acetate, succinate, and citrate) as a function of their pH, capacity, and tonicity. The myotoxicity of these buffers in the range of pH 2-6 and 0.001-0.1 M buffer capacity was assessed using cumulative creatine kinase (CK) release from an isolated rodent muscle model following injection. Phenytoin and 0.9% NaCl injection were used as positive and negative controls, respectively. Buffer solutions were prepared. A lower pH and higher buffer capacity was linked to increased myotoxicity for the acetate buffers. However, for succinate and citrate buffers, pH appeared to influence the extent of myotoxicity, whereas buffer capacity did not seem to have an effect. When either NaCl or trehalose was used as a tonicity-adjusting agent at pH 6, isotonic 0.01 M buffer solutions dramatically lowered the cumulative CK release compared to those that were not isotonic. Isotonic succinate buffers displayed the lowest myotoxicity, whereas citrate buffers displayed the highest values. Citrate buffers containing three carboxylic acid groups showed higher myotoxicity than succinate buffers and acetate buffers at 0.001 and 0.01 M buffer capacities, whereas acetate buffer produced higher cumulative CK release than citrate and succinate buffers at 0.1 M buffer capacity. The myotoxicity of pharmaceutical buffers containing carboxylic acid groups appears to be directly affected by lowering the pH of the solution.

Current perspectives on pain upon injection of drugs

A limitation in the administration of parenteral products is the pain caused upon injection. Injection site pain has been predominately associated with intravenous, intramuscular, and subcutaneous administration. It becomes important for the formulation scientist to have a basic understanding of the physiology underlying the pain process, as well as the pharmaceutical factors associated with injection site pain. Initially, this review will provide the reader with a primer on the mediation of pain in the periphery and a compilation of those drugs that have been associated with pain on injection. In addition, this review will present important considerations and general formulation approaches or methods that have been used to overcome pain on injection. Finally, a brief overview of the various experimental systems used to investigate injection site pain is discussed.

Local tolerance of subcutaneous injections

Human insulin-like growth factor I (hIGF-I) has several possible clinical applications. Because subcutaneous administration of the drug can cause pain, local tolerance to injection of different formulations with or without hIGF-I has been investigated in man using isotonic saline solution as reference. The formulations, made isotonic with NaCl, ranged in pH from 6 to 7 with phosphate buffer concentrations of 5 to 50 mM. The local tolerance after injection was assessed as injection pain on a visual analogue scale, pain duration and local tolerance (redness, paleness and oedema). The discomfort at the injection site was lowest with 10 mM phosphate, pH 7. Injection of buffer at pH 6 (50 mM phosphate) caused significantly more pain than using 10 mM phosphate, whereas the pain at pH 6 using 10 mM phosphate did not differ significantly from that experienced on injection of the solution at pH 7 using either 10 or 50 mM phosphate. hIGF-I itself did not seem to cause pain. We concluded that for subcutaneous injections at non-physiological pH, the buffer strength should be kept as low as possible to avoid pain upon injection. We also hypothesize that when a non-physiological pH must be used for stability reasons, a lower buffer strength enables more rapid normalization of the pH at the injection site.

Recombinant human erythropoietin therapy in children on dialysis

The addition of recombinant human erythropoietin (rHuEPO) to the therapeutic regimen for children with chronic renal failure (CRF) is one of the most important improvements in care in the last 20 years. Anemia had played an important role in the morbidity of chronic dialysis treatment. Before the availability of rHuEPO, repeated erythrocyte transfusions provided incomplete treatment and had significant long-term sequelae. Recombinant erythropoietin treatment resulted in the amelioration of anemia and marked reduction in transfusions. Additional benefits of the correction of anemia with rHuEPO include improvements in exercise tolerance and regression of ventricular hypertrophy. Many rHuEPO-treated patients have had subjective increases in appetite, but there has been no consistent improvement in dietary intake or anthropometric measures. Correction of anemia with rHuEPO has not been shown to improve the growth of children with CRF receiving dialysis. The most significant adverse effects of rHuEPO are the development of iron deficiency and the exacerbation or development de novo of hypertension. RHuEPO treatment has been shown to treat the anemia of CRF in children safely and effectively. In most cases, putative inhibitors of erythropoiesis and blood loss can be overcome. Many of the symptoms previously ascribed to "uremia" have improved with correction of anemia. The full implications of treatment of anemia with rHuEPO will be clearer when the health outcomes for children who never become severely anemic or require transfusions are more completely studied.

New hormones in the therapeutic arsenal of chronic renal failure. Growth hormone and erythropoietin

Although the benefits of rhGH and r-HuEPO therapy in children with CRF and on dialysis are already significant, further study of these new additions to the therapeutic arsenal remains necessary. Data on the final adult height achieved in patients who receive rhGH are extremely important information that is as yet unavailable. The risks and benefits of raising the target hematocrit to a "normal" value in patients receiving r-HuEPO remains under study. Only when these and other issues are soundly evaluated will the full impact of these medications be understood.

Intraperitoneal erythropoietin treatment of children with chronic renal failure

Intraperitoneal erythropoietin was given to three children on chronic peritoneal dialysis. Doses between 100 and 150 units/kg were given undiluted into a dry cavity twice weekly and left for 10-12 h before resuming dialysis. Satisfactory haemoglobin levels were seen over a 6-month period and there were no complications. Intraperitoneal administration of erythropoietin is cost-effective and avoids the local pain of subcutaneous injections.

Effect of lidocaine on the hematopoietic properties of recombinant human erythropoietin in the uremic rat

Subcutaneous injections of recombinant human erythropoietin (rHuEPO) produce considerable pain which can result in noncompliance. As a prelude to an investigation of the possible use of local anesthetics as additives to subcutaneous rHuEPO, we examined the effect of the addition of lidocaine on the erythropoietic properties of rHuEPO. Two weeks after 5/6 nephrectomy, 22 rats were randomly assigned to the following groups: normal saline, rHuEPO, lidocaine, and rHuEPO plus lidocaine. Injections were given three times a week for 2 weeks. No change in hematocrit was observed in the saline and lidocaine groups. The hematocrit of the rHuEPO rats increased from 44.5 +/- 1.4% (mean +/- SD) to 61.6 +/- 2.1% (P < 0.0005), and that of the rHuEPO plus lidocaine group from 42.8 +/- 4.3% to 63.9 +/- 3.0% (P < 0.005), with no difference between the groups. We conclude that the combination of rHuEPO plus lidocaine is as effective as rHuEPO alone in increasing the hematocrit of rats with chronic renal failure.

Effect of recombinant erythropoietin therapy on autoimmunity in systemic lupus erythematosus

Previous studies of the in vitro effects of recombinant erythropoietin (rEPO) on T and B cells and studies of lymphocyte subsets in dialysis patients receiving rEPO therapy suggest that rEPO might augment immune responses. In the present study indices of autoimmunity (antinuclear antibody, anti-double-stranded DNA, and antiphospholipid antibody [immunoglobulins G and M]) were measured before, during, and after rEPO therapy in five systemic lupus erythematosus patients without renal failure (mean serum creatinine, 1.5 +/- 0.3 mg/dL). The rEPO therapy was self-administered by subcutaneous injection in doses ranging from 4,000 units once weekly to 3,000 units three times weekly for 3 to 7 months. On rEPO therapy, each patient experienced an increase in hematocrit. The mean baseline hematocrit increased from 32 +/- 2.0 to a peak of 42.2 +/- 3 (P < 0.001) at 3 to 7 months and then decreased to baseline values 1 to 2 months after rEPO was discontinued. During this time the indices of autoimmunity were not significantly changed by rEPO therapy. Systemic lupus erythematosus activity, assessed by serum C3, serum creatinine, urinalysis, and 24-hour proteinuria, also was unchanged by rEPO therapy. The rEPO therapy was generally well tolerated. However, one patient, who was also receiving replacement estrogen therapy and had high-titer antiphospholipid antibody, experienced episodes of thrombophlebitis while on rEPO therapy. In conclusion, we found no evidence that rEPO increases autoimmunity in systemic lupus erythematosus. However, we observed a temporal relationship between episodes of thrombophlebitis and rEPO therapy in a single patient with high-titer anticardiolipin antibody who was also receiving replacement estrogen therapy. These associations require further investigation.