Propranolol pharmacokinetics in infants treated for Infantile Hemangiomas requiring systemic therapy: Modeling and dosing regimen recommendations

Personalized Dosing of Medicines for Children: A Primer on Pediatric Pharmacometrics for Clinicians

The widespread use of drugs for unapproved purposes remains common in children, primarily attributable to practical, ethical, and financial constraints associated with pediatric drug research. Pharmacometrics, the scientific discipline that involves the application of mathematical models to understand and quantify drug effects, holds promise in advancing pediatric pharmacotherapy by expediting drug development, extending applications, and personalizing dosing. In this review, we delineate the principles of pharmacometrics, and explore its clinical applications and prospects. The fundamental aspect of any pharmacometric analysis lies in the selection of appropriate methods for quantifying pharmacokinetics and pharmacodynamics. Population pharmacokinetic modeling is a data-driven method ('top-down' approach) to approximate population-level pharmacokinetic parameters, while identifying factors contributing to inter-individual variability. Model-informed precision dosing is increasingly used to leverage population pharmacokinetic models and patient data, to formulate individualized dosing recommendations. Physiologically based pharmacokinetic models integrate physicochemical drug properties with biological parameters ('bottom-up approach'), and is particularly valuable in situations with limited clinical data, such as early drug development, assessing drug-drug interactions, or adapting dosing for patients with specific comorbidities. The effective implementation of these complex models hinges on strong collaboration between clinicians and pharmacometricians, given the pivotal role of data availability. Promising advancements aimed at improving data availability encompass innovative techniques such as opportunistic sampling, minimally invasive sampling approaches, microdialysis, and in vitro investigations. Additionally, ongoing research efforts to enhance measurement instruments for evaluating pharmacodynamics responses, including biomarkers and clinical scoring systems, are expected to significantly bolster our capacity to understand drug effects in children.

Propranolol Therapy in Infantile Hemangioma: It Is Not Just About the Beta

BACKGROUND

Propranolol, a nonselective β-adrenergic receptor antagonist, is approved by the U.S. Food and Drug Administration to treat problematic infantile hemangiomas, but a subset of patients experience treatment complications. Parents wary of long-term use and side effects consult plastic surgeons on surgical options or as a second opinion. Understanding the mechanism(s) of action of propranolol will allow plastic surgeons to better inform parents.

METHODS

A systemic literature search was performed to query published translational and basic science studies on propranolol effects on infantile hemangiomas and cells derived from these lesions.

RESULTS

In experimental studies, propranolol was antiproliferative and cytotoxic against hemangioma endothelial and stem cells and affected infantile hemangioma perivascular cell contractility. Propranolol inhibited migration, network formation, vascular endothelial growth factor A production, and vascular endothelial growth factor receptor 2 activation and down-regulated PI3K/AKT and mitogen-activated protein kinase signaling in hemangioma endothelial cells, but it increased ERK1/2 activity in hemangioma stem cells. At effective clinical doses, measured propranolol plasma concentration is 100 times higher than necessary for complete β-adrenergic receptor blockade, yet was 10 to 100 times less than required to induce hemangioma stem cell death.

CONCLUSIONS

Propranolol targets multiple cell types in infantile hemangiomas by means of β-adrenergic receptor-dependent and -independent mechanisms. Plasma concentration played a significant role. At clinically relevant doses, incomplete infantile hemangioma suppression may explain the rebound phenomenon and worsening ulceration, and propranolol off target effects may lead to commonly reported adverse effects, such as sleep and gastrointestinal disturbances. Propranolol limitations and complications underscore the importance of surgical treatment options in cases of rebound and severe adverse effects. Surgical intervention remains an important treatment choice when parents are hesitant to use propranolol.

Critical role of Aquaporin-1 and telocytes in infantile hemangioma response to propranolol beta blockade

Propranolol, a nonselective β-adrenergic receptor (ADRB) antagonist, is the first-line therapy for severe infantile hemangiomas (IH). Since the incidental discovery of propranolol efficacy in IH, preclinical and clinical investigations have shown evidence of adjuvant propranolol response in some malignant tumors. However, the mechanism for propranolol antitumor effect is still largely unknown, owing to the absence of a tumor model responsive to propranolol at nontoxic concentrations. Immunodeficient mice engrafted with different human tumor cell lines were treated with anti-VEGF bevacizumab to create a model sensitive to propranolol. Proteomics analysis was used to reveal propranolol-mediated protein alteration correlating with tumor growth inhibition, and Aquaporin-1 (AQP1), a water channel modulated in tumor cell migration and invasion, was identified. IH tissues and cells were then functionally investigated. Our functional protein association networks analysis and knockdown of ADRB2 and AQP1 indicated that propranolol treatment and AQP1 down-regulation trigger the same pathway, suggesting that AQP1 is a major driver of beta-blocker antitumor response. Examining AQP1 in human hemangioma samples, we found it exclusively in a perivascular layer, so far unrecognized in IH, made of telocytes (TCs). Functional in vitro studies showed that AQP1-positive TCs play a critical role in IH response to propranolol and that modulation of AQP1 in IH-TC by propranolol or shAQP1 decreases capillary-like tube formation in a Matrigel-based angiogenesis assay. We conclude that IH sensitivity to propranolol may rely, at least in part, on a cross talk between lesional vascular cells and stromal TCs.

Clinical Pharmacokinetics of Propranolol Hydrochloride: A Review

BACKGROUND

Nobel laureate Sir James Black's molecule, propranolol, still has broad potential in cardiovascular diseases, infantile haemangiomas and anxiety. A comprehensive and systematic review of the literature for the summarization of pharmacokinetic parameters would be effective to explore the new safe uses of propranolol in different scenarios, without exposing humans and using virtual-human modeling approaches.

OBJECTIVE

This review encompasses physicochemical properties, pharmacokinetics and drug-drug interaction data of propranolol collected from various studies.

METHODS

Clinical pharmacokinetic studies on propranolol were screened using Medline and Google Scholar databases. Eighty-three clinical trials, in which pharmacokinetic profiles and plasma time concentration were available after oral or IV administration, were included in the review.

RESULTS

The study depicts that propranolol is well absorbed after oral administration. It has dose-dependent bioavailability, and a 2-fold increase in dose results in a 2.5-fold increase in the area under the curve, a 1.3-fold increase in the time to reach maximum plasma concentration and finally, 2.2 and 1.8-fold increase in maximum plasma concentration in both immediate and long-acting formulations, respectively. Propranolol is a substrate of CYP2D6, CYP1A2 and CYP2C19, retaining potential pharmacokinetic interactions with co-administered drugs. Age, gender, race and ethnicity do not alter its pharmacokinetics. However, in renal and hepatic impairment, it needs a dose adjustment.

CONCLUSION

Physiochemical and pooled pharmacokinetic parameters of propranolol are beneficial to establish physiologically based pharmacokinetic modeling among the diseased population.

A survey on the application of oral propranolol and atenolol for the management of infantile hemangiomas in mainland China: Survey on propranolol atenolol hemangiomas

Since 2008, oral propranolol has evolved as the first-line therapy for infantile hemangiomas (IHs). Meanwhile, oral atenolol gradually shows comparative effectiveness versus oral propranolol with few side effects. Here, we conducted a mobile internal survey among a group of Chinese clinicians about how they choose the dosage, dose regimen, and dose escalation methods of propranolol and atenolol for the treatment of IH.A mobile-ready internal survey on the application of oral propranolol and oral atenolol for IH in mainland China was performed and distributed to 333 potential clinicians from different levels of healthcare institutions in mainland China. Eighty-one doctors responded to the survey. All the respondents had the experience of treating IH with oral propranolol and 32 had the experience with oral atenolol.Most of the doctors from tertiary hospitals chose 2 mg/kg/d twice daily, while most of those with the experience of propranolol from private hospitals chose 1 mg/kg/d once daily. More doctors from tertiary hospitals had the experience of atenolol than those from private hospitals.Oral atenolol has become another medication intervention option for IH in mainland China. This survey is helpful to standardize and develop a guideline of oral atenolol therapy for IH.

Hemangiol in infantile haemangioma: A paediatric post-marketing surveillance drug study

AIM

Infantile haemangioma (IH) is the most common benign tumour in children. Since 2014, propranolol has become the first-choice therapy and currently Hemangiol is the only approved drug for complicated haemangioma. This post-marketing study reports the use of Hemangiol for IH in paediatric practice.

METHOD AND RESULTS

From January 2014 to November 2018, 94 children (median age 4 [0; 21] months; 75% female) treated with Hemangiol for proliferative IH were enrolled in the study. The systematic paediatric cardiology consultation never contraindicated beta-blockers. Two Hemangiol initiation protocols were used: a conventional ambulatory 3-week titration phase protocol (n = 76, 80.9%), and a rapid initiation protocol with a 48-hour dose escalation in conventional hospitalization for severe proliferative or ulcerated IH (n = 18, 19.1%). In both protocols, the haemodynamic tolerance was good. The mean maintenance dose of Hemangiol was 2.7 ± 0.8 mg/kg/day, with a median treatment duration of 7 [1.5; 19] months. Adverse events (AEs) have been found in 25 (26,6%) patients, including 8 (8.5%) patients with serious AEs (uncontrolled bronchial hyperreactivity, n = 5; serious hypoglycaemia, n = 3). Some patients had one or more AEs, a total of 24 nonserious AEs was reported in 19 patients (sleep disturbances, n = 9; respiratory disorders, n = 5; digestive disorders, n = 6). No cardiac adverse event was reported.

CONCLUSION

This post-marketing surveillance drug study supports the good tolerance of Hemangiol in children with IH. A rapid initiation protocol is of interest when treatment is urgent. The pretherapeutic paediatric cardiology consultation should not be systematic but only indicated for specific patients. CLINICALTRIALS.GOV: NCT04105517.

Retrospective case series of increased oral propranolol dosage for infantile hemangiomas

BACKGROUND

Infantile hemangiomas (IH) are the most common benign tumor of infancy. Although oral propranolol is currently first-line therapy, optimal dosing for treatment of IH remains debated. We sought to identify hemangioma characteristics associated with poor response to standard dosing (2 mg/kg/d) and to assess the therapeutic benefit of higher dosing.

METHODS

Retrospective chart review was conducted of 559 patients with IH seen at Johns Hopkins between 2008 and 2018, of whom 245 (44%) were treated with propranolol. Baseline characteristics were compared between patients who received increased propranolol dosing (≥2.5 mg/kg/d) and those who remained on standard dose (2 mg/kg/d). Changes in the Hemangioma Activity Score (HAS) during the increased dosage period were scored by two trained, blinded pediatric dermatologists.

RESULTS

Of 245 patients, 204 (83%) received standard 2 mg/kg/d propranolol dosing while 41 (17%) received a higher dose of ≥2.5 mg/kg/d. The most common location of IH in both groups was the face. In the increased dosage group, 85.4% of IH were of mixed or deep morphology with a mean greatest diameter of 4.6 cm. IH requiring increased dosing received longer courses of propranolol (mean of 389 vs. 282 days, P < .001) and underwent higher rates of excision by plastic surgery (26.8% vs. 5.9%, P < .001). Mean change in HAS over the period with dosage ≥2.5 mg/kg/d was minimal (-0.70; P < .001).

CONCLUSIONS

Most recalcitrant IH were located on the face, larger in diameter, and of mixed or deep morphology. Patients had little improvement in HAS score with increased propranolol dosing implemented late in the treatment course with over one-fourth ultimately receiving surgical excision.

The adrenergic receptor antagonists propranolol and carvedilol decrease bone sarcoma cell viability and sustained carvedilol reduces clonogenic survival and increases radiosensitivity in canine osteosarcoma cells

Adrenergic receptor (AR) expression has been demonstrated at several sites of primary and metastatic tumour growth and may influence proliferation, survival, metastasis and angiogenesis. AR antagonists like propranolol and carvedilol inhibit proliferation, induce apoptosis and synergize with chemotherapy agents in some cancers. Radiation resistance is mediated in many cells by upregulation of pro-survival pathways, which may be influenced by ARs. Studies evaluating AR antagonists combined with radiation are limited. The purpose of this study was to determine the effect of propranolol and carvedilol on viability and radiosensitivity in sarcoma cell lines. The hypothesis was that propranolol and carvedilol would increase radiosensitivity in four primary bone sarcoma cell lines. Single agent propranolol or carvedilol inhibited cell viability in all cell lines in a concentration-dependent manner. The mean inhibitory concentrations (IC₅₀ ) for carvedilol were approximately 4-fold lower than propranolol and may be clinically relevant in vivo. Immunoblot analysis confirmed AR expression in both human and canine sarcoma cell lines; however, there was no correlation between baseline AR protein expression and radiosensitivity. Short duration treatment with carvedilol and propranolol did not significantly affect clonogenic survival. Prolonged exposure to propranolol and carvedilol significantly decreased the surviving fraction of canine osteosarcoma cells after 3Gy radiation. Based on our results and possible in vivo activity in dogs, further studies investigating the effects of carvedilol on sarcoma are warranted.