Subcutaneous administration of benzathine benzylpenicillin G has favourable pharmacokinetic characteristics for the prevention of rheumatic heart disease compared with intramuscular injection: a randomized, crossover, population pharmacokinetic study in healthy adult volunteers

Patient preferences for prophylactic regimens requiring regular injections in children and adolescents: a systematic review and thematic analysis

BACKGROUND

At present, limited literature exists exploring patient preferences for prophylactic treatment of acute rheumatic fever (ARF) and rheumatic heart disease (RHD). Given low treatment completion rates to this treatment in Australia, where the burden of disease predominantly affects Aboriginal and Torres Strait Islander people, an improved understanding of factors driving patient preference is required to improve outcomes. Due to limited available literature, this review sought to explore treatment preferences for conditions for which the findings might be generalisable to the ARF/RHD context.

OBJECTIVE

Explore treatment preferences of patients, parents/caregivers and healthcare providers towards regular injection regimens in paediatric and adolescent populations for any chronic condition. Findings will be applied to the development of benzathine penicillin G (BPG) prophylactic regimens that are informed by treatment preferences of patients and their caregivers. This in turn should contribute to optimisation of successful BPG delivery.

METHODS

A systematic review of databases (Medline, Embase and Global Health) was conducted using a search strategy developed with expert librarian input. Studies were selected using a two-stage process: (1) title and abstract screen and (2) full text review. Data were extracted using a reviewer-developed template and appraised using the JBI Critical Appraisal tool. Data were synthesised according to a thematic analytical framework.

RESULTS

1725 papers were identified by the database search, conducted between 12 February 2022 and 8 April 2022, and 25 were included in the review. Line-by-line coding to search for concepts generated 20 descriptive themes. From these, five overarching analytical themes were derived inductively: (1) ease of use, (2) tolerability of injection, (3) impact on daily life, (4) patient/caregiver agency and (5) home/healthcare interface.

CONCLUSIONS

The findings of this review may be used to inform the development of preference-led regular injection regimens for paediatric and adolescent patient cohorts-specifically for BPG administration in ARF/RHD secondary prophylaxis.

TRIAL REGISTRATION NUMBER

Patient, parent and health personnel preferences towards regular injection regimes in paediatric and adolescent populations-a protocol for a systematic review. PROSPERO 2021 CRD42021284375. Available from: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021284375.

"Hurts less, lasts longer"; a qualitative study on experiences of young people receiving high-dose subcutaneous injections of benzathine penicillin G to prevent rheumatic heart disease in New Zealand

BACKGROUND

Four-weekly intramuscular (IM) benzathine penicillin G (BPG) injections to prevent acute rheumatic fever (ARF) progression have remained unchanged since 1955. A Phase-I trial in healthy volunteers demonstrated the safety and tolerability of high-dose subcutaneous infusions of BPG which resulted in a much longer effective penicillin exposure, and fewer injections. Here we describe the experiences of young people living with ARF participating in a Phase-II trial of SubCutaneous Injections of BPG (SCIP).

METHODOLOGY

Participants (n = 20) attended a clinic in Wellington, New Zealand (NZ). After a physical examination, participants received 2% lignocaine followed by 13.8mL to 20.7mL of BPG (Bicillin-LA®; determined by weight), into the abdominal subcutaneous tissue. A Kaupapa Māori consistent methodology was used to explore experiences of SCIP, through semi-structured interviews and observations taken during/after the injection, and on days 28 and 70. All interviews were recorded, transcribed verbatim, and thematically analysed.

PRINCIPAL FINDINGS

Low levels of pain were reported on needle insertion, during and following the injection. Some participants experienced discomfort and bruising on days one and two post dose; however, the pain was reported to be less severe than their usual IM BPG. Participants were 'relieved' to only need injections quarterly and the majority (95%) reported a preference for SCIP over IM BPG.

CONCLUSIONS

Participants preferred SCIP over their usual regimen, reporting less pain and a preference for the longer time gap between treatments. Recommending SCIP as standard of care for most patients needing long-term prophylaxis has the potential to transform secondary prophylaxis of ARF/RHD in NZ and globally.

Lack of awareness of secondary rheumatic prevention in preoperative candidates for mitral valve surgery - alarming situation

BACKGROUND

We conducted this study to assess the compliance with secondary rheumatic prophylaxis among preoperative patients with rheumatic mitral valve disease undergoing valvular heart surgery at a tertiary care cardiac hospital in a developing country.

METHODS

This is a descriptive cross-sectional study conducted at a tertiary care cardiac hospital in Karachi, Pakistan. The inclusion criteria encompassed patients of any sex, aged between 18 and 80 years, who had been diagnosed with rheumatic mitral valve disease through transthoracic echocardiography and had undergone valvular heart surgery. The level of compliance with secondary rheumatic prophylaxis and barriers toward noncompliance was assessed during routine preoperative interview session. This preventive measure plays a crucial role in reducing the progression of the disease and improving patient outcomes.

RESULTS

Out of the 239 patients included in the study, 125 (52.3%) were females, with a mean age of 38.8 ± 11.8 years. The majority of patients (88.7%) came from rural areas. Among the patients, 79 (33.1%) received rheumatic prophylaxis, while 160 (66.9%) did not adhere to it regularly. The common barriers for receiving rheumatic prophylaxis were non availability (41.0%) and nonaffordability (40.6%). Additionally, 28.0% of patients had lacked awareness of the importance of rheumatic prophylaxis, and 2.5% expressed fear of injection site pain and subsequent symptoms.

CONCLUSIONS

A concerning level of noncompliance with secondary rheumatic prophylaxis was observed. The barriers identified in patients who did not receive rheumatic prophylaxis were primarily related to affordability, availability, lack of awareness, and fear of injection site pain and subsequent symptoms.

The Subcutaneous Administration of Beta-Lactams: A Case Report and Literary Review-To Do Small Things in a Great Way

The subcutaneous (s.c.) route is a commonly used method for delivering various drugs, although its application in the administration of antibiotics is relatively uncommon. In this case, we report a successful treatment of nosocomial pneumonia using piperacillin/tazobactam via continuous subcutaneous administration. Furthermore, this article provides an overview of the current literature regarding the s.c. administration of beta-lactam antibiotics. Based on our analysis, we identified only 15 studies that described the s.c. use of beta-lactam antibiotics in human subjects. Among these studies, cephalosporins were the most extensively investigated antibiotic class, with 10 available studies. According to the study findings, all three antibiotic classes (cephalosporins, penicillins, and carbapenems) demonstrated a similar pharmacokinetic profile when administered via the subcutaneous route. The subcutaneous route appears to be associated with a lower peak serum concentration (Cmax) but a comparable minimum blood concentration (Cmin) and an extended half-life (t1/2) when compared to conventional routes of antibiotic administration. Further research is necessary to determine whether subcutaneously administered beta-lactam antibiotics in human subjects achieve pharmacodynamic targets and demonstrate clinical efficacy.

Subcutaneous infusion of high-dose benzathine penicillin G is safe, tolerable, and suitable for less-frequent dosing for rheumatic heart disease secondary prophylaxis: a phase 1 open-label population pharmacokinetic study

Since 1955, the recommended strategy for rheumatic heart disease (RHD) secondary prophylaxis has been benzathine penicillin G [BPG; 1.2 MU (900 mg)] injections administered intramuscularly every 4 weeks. Due to dosing frequency, pain, and programmatic challenges, adherence is suboptimal. It has previously been demonstrated that BPG delivered subcutaneously at a standard dose is safe and tolerable and has favorable pharmacokinetics, setting the scene for improved regimens with less frequent administration. The safety, tolerability, and pharmacokinetics of subcutaneous infusions of high-dose BPG were assessed in 24 healthy adult volunteers assigned to receive either 3.6, 7.2, or 10.8 MU (three, six, and nine times the standard dose, respectively) as a single subcutaneous infusion. The delivery of the BPG to the subcutaneous tissue was confirmed with ultrasonography. Safety assessments, pain scores, and penicillin concentrations were measured for 16 weeks post-dose. Subcutaneous infusion of penicillin (SCIP) was generally well tolerated with all participants experiencing transient, mild infusion-site reactions. Prolonged elevated penicillin concentrations were described using a combined zero-order (44 days) and first-order (t1/2 = 12 days) absorption pharmacokinetic model. In simulations, time above the conventionally accepted target concentration of 20 ng/mL (0.02 µg/mL) was 57 days for 10.8 MU delivered by subcutaneous infusion every 13 weeks compared with 9 days of every 4-weekly dosing interval for the standard 1.2 MU intramuscular dose (i.e., 63% and 32% of the dosing interval, respectively). High-dose SCIP (BPG) is safe, has acceptable tolerability, and may be suitable for up to 3 monthly dosing intervals for secondary prophylaxis of RHD.

Development of a sustained release implant of benzathine penicillin G for secondary prophylaxis of rheumatic heart disease

BACKGROUND

Regular intramuscular (i.m.) benzathine penicillin G (BPG) injections have been the cornerstone of rheumatic heart disease (RHD) secondary prophylaxis since the 1950s. Patient adherence to IM BPG is poor, largely due to pain, the need for regular injections every 3-4 weeks and health sector delivery challenges in resource-limited settings. There is an urgent need for new approaches for secondary prophylaxis, such as an implant which could provide sustained penicillin concentrations for more than 6 months.

METHODS

In this study we developed and evaluated a slow release implant with potential for substantially extended treatment. The side wall of a solid drug rich core was coated with polycaprolactone which acts as an impermeable barrier. The exposed surfaces at the ends of the implant defined the release surface area, and the in vitro release rate of drug was proportional to the exposed surface area across implants of differing diameter. The in vivo pharmacokinetics and tolerability of the implants were evaluated in a sheep model over 9 weeks after subcutaneous implantation.

RESULTS

The absolute release rates obtained for the poorly water-soluble benzathine salt were dependent on the exposed surface area demonstrating the impermeability of the wall of the implant. The implants were well-tolerated after subcutaneous implantation in a sheep model, without adverse effects at the implantation site. Gross structural integrity was maintained over the course of the study, with erosion limited to the dual-exposed ends. Steady release of penicillin G was observed over the 9 weeks and resulted in approximately constant plasma concentrations close to accepted target concentrations.

CONCLUSION

In principle, a long acting BPG implant is feasible as an alternative to IM injections for secondary prophylaxis of RHD. However, large implant size is currently a significant impediment to clinical utility and acceptability.

Evaluation of a Community-Led Program for Primordial and Primary Prevention of Rheumatic Fever in Remote Northern Australia

Environmental factors including household crowding and inadequate washing facilities underpin recurrent streptococcal infections in childhood that cause acute rheumatic fever (ARF) and subsequent rheumatic heart disease (RHD). No community-based 'primordial'-level interventions to reduce streptococcal infection and ARF rates have been reported from Australia previously. We conducted a study at three Australian Aboriginal communities aiming to reduce infections including skin sores and sore throats, usually caused by Group A Streptococci, and ARF. Data were collected for primary care diagnoses consistent with likely or potential streptococcal infection, relating to ARF or RHD or related to environmental living conditions. Rates of these diagnoses during a one-year Baseline Phase were compared with a three-year Activity Phase. Participants were children or adults receiving penicillin prophylaxis for ARF. Aboriginal community members were trained and employed to share knowledge about ARF prevention, support reporting and repairs of faulty health-hardware including showers and provide healthcare navigation for families focusing on skin sores, sore throat and ARF. We hypothesized that infection-related diagnoses would increase through greater recognition, then decrease. We enrolled 29 participants and their families. Overall infection-related diagnosis rates increased from Baseline (mean rate per-person-year 1.69 [95% CI 1.10-2.28]) to Year One (2.12 [95% CI 1.17-3.07]) then decreased (Year Three: 0.72 [95% CI 0.29-1.15]) but this was not statistically significant (p = 0.064). Annual numbers of first-known ARF decreased, but numbers were small: there were six cases of first-known ARF during Baseline, then five, 1, 0 over the next three years respectively. There was a relationship between household occupancy and numbers (p = 0.018), but not rates (p = 0.447) of infections. This first Australian ARF primordial prevention study provides a feasible model with encouraging findings.

Smart design of patient centric long-acting products: from preclinical to marketed pipeline trends and opportunities

INTRODUCTION

We see a development in the field of long-acting products to serve patients with chronic diseases by providing benefits in adherence, efficacy and safety of the treatment. This review investigates features of long-acting products on the market/pipeline to understand which drug substance (DS) and drug product (DP) characteristics likely enable a successful patient-centric, low-dosing frequency product.

AREAS COVERED

This review evaluates marketed/pipeline long-acting products with greater than one week release of small molecules and peptides by oral and injectable route of administration (RoA), with particular focus on patient centricity, adherence impact, health outcomes, market trends, and the match of DS/DP technologies which lead to market success.

EXPERT OPINION

Emerging trends are expected to change the field of long-acting products in the upcoming years by increasing capability in engineered molecules (low solubility, long half-life, high potency, etc.), directly developing DP as long-acting oral/injectable, increasing the proportion of products for local drug delivery, and a direction towards more subcutaneous, self-administered products. Among long-acting injectable products, nanosuspensions show a superiority in dose per administration and dosing interval, overwhelming the field of infectious diseases with the recently marketed products.

Population pharmacokinetic study of benzathine penicillin G administration in Indigenous children and young adults with rheumatic heart disease in the Northern Territory, Australia

BACKGROUND

Benzathine penicillin G (BPG) is the cornerstone of secondary prophylaxis to prevent Streptococcus pyogenes infections, which precede acute rheumatic fever (ARF). The paucity of pharmacokinetic (PK) data from children and adolescents from populations at the highest risk of ARF and rheumatic heart disease (RHD) poses a challenge for determining the optimal dosing and frequency of injections and undermines efforts to develop improved regimens.

METHODS

We conducted a 6 month longitudinal PK study of young people receiving BPG for secondary prophylaxis. Throat and skin swabs were collected for microbiological culture along with dried blood spot (DBS) samples for penicillin concentrations. DBSs were assayed using LC-MS/MS. Penicillin concentration datasets were analysed using non-linear mixed-effects modelling and simulations performed using published BMI-for-age and weight-for-age data.

RESULTS

Nineteen participants provided 75 throat swabs, 3 skin swabs and 216 penicillin samples. Throat cultures grew group C and G Streptococcus. Despite no participant maintaining penicillin concentration >20 ng/mL between doses, there were no S. pyogenes throat infections and no ARF. The median (range) observed durations >20 ng/mL for the low- and high-BMI groups were 14.5 (11.0-24.25) and 15.0 (7.5-18.25) days, respectively.

CONCLUSIONS

Few patients at highest risk of ARF/RHD receiving BPG for secondary prophylaxis maintain penicillin concentrations above the target of 20 ng/mL beyond 2 weeks during each monthly dosing interval. These PK data suggest that some high-risk individuals may get inadequate protection from every 4 week dosing. Future research should explore this gap in knowledge and PK differences between different populations to inform future dosing schedules.

High risk of early sub-therapeutic penicillin concentrations after intramuscular benzathine penicillin G injections in Ethiopian children and adults with rheumatic heart disease

Introduction

Intramuscular benzathine penicillin G (BPG) injections are a cornerstone of secondary prophylaxis to prevent acute rheumatic fever (ARF) and rheumatic heart disease (RHD). Uncertainties regarding inter-ethnic and preparation variability, and target exposure profiles of BPG injection are key knowledge gaps for RHD control.

Methods

To evaluate BPG pharmacokinetics (PK) in patients receiving 4-weekly doses in Ethiopia, we conducted a prospective cohort study of ARF/RHD patients attending cardiology outpatient clinics. Serum samples were collected weekly for one month after injection and assayed with a liquid chromatography-mass spectroscopy assay. Concentration-time datasets for BPG were analyzed by nonlinear mixed effects modelling using NONMEM.

Results

A total of 190 penicillin concentration samples from 74 patients were included in the final PK model. The median age, weight, BMI was 21 years, 47 kg and 18 kg/m², respectively. When compared with estimates derived from Indigenous Australian patients, the estimate for median (95% confidence interval) volume of distribution (V/F) was lower (54.8 [43.9–66.3] l.70kg^-1) whilst the absorption half-life (t_1/2-abs2) was longer (12.0 [8.75–17.7] days). The median (IQR) percentage of time where the concentrations remained above 20 ng/mL and 10 ng/mL within the 28-day treatment cycle was 42.5% (27.5–60) and 73% (58.5–99), respectively.

Conclusions

The majority of Ethiopian patients receiving BPG as secondary prophylaxis to prevent RHD do not attain target concentrations for more than two weeks during each 4-weekly injection cycle, highlighting the limitations of current BPG strategies. Between-population variation, together with PK differences between different preparations may be important considerations for ARF/RHD control programs.

Rheumatic heart disease (RHD) is the most common form of acquired heart disease in Ethiopia across all age groups. Monthly benzathine penicillin G (BPG) injections remains the cornerstone of secondary prophylaxis to prevent recurrent acute rheumatic fever (ARF) and progression to RHD, but data supporting the optimal dose and timing of BPG injections is a major knowledge gap for National RHD control programs, particularly amongst the highest risk groups. In this study we measured penicillin concentrations in Ethiopian patients receiving regular BPG injections. It demonstrates that that most Ethiopian patients receiving BPG as secondary prophylaxis to prevent RHD do not maintain target concentrations for more than two weeks during each 4-weekly injection cycle. This study highlights the limitation of the current BPG dosing recommendations and underpin global calls for improved penicillin formulations and better dosing and delivery strategies.