Is laronidase approved?

Yes. It was approved by both the US FDA and the European Medicines Agency in 2003, marketed as Aldurazyme.

How often is laronidase given?

As an intravenous infusion once weekly (0.58 mg/kg), which differs from the every-2-week schedule used for imiglucerase and agalsidase beta.

Does laronidase treat the brain effects of Hurler syndrome?

No. The infused enzyme does not cross the blood-brain barrier, so cognitive and other central nervous system features of severe MPS I are not treated; stem cell transplant is used for that in eligible young patients.

What are the main safety concerns?

Infusion-associated reactions are common and anti-drug antibodies form in most patients; serious hypersensitivity including anaphylaxis has occurred, so infusions are monitored and managed by specialists.

EMA-approvedaka Aldurazyme

Laronidase — Complete Research Guide (2026)

Last updated 2026-06-30

TL;DR

Laronidase (also known as Aldurazyme) is a peptide catalogued under Enzymes (MPS I). Neutral reference entry; EU status: EU-approved prescription medicine.

What is Laronidase?

Laronidase (brand name Aldurazyme) is a recombinant human alpha-L-iduronidase approved as enzyme replacement therapy for mucopolysaccharidosis type I (MPS I; Hurler, Hurler-Scheie and moderate-to-severe Scheie forms); it was approved by the US FDA and the EMA in 2003.

Its evidence base includes an early open-label phase 1/2 study, a pivotal randomised double-blind placebo-controlled phase 3 trial, and multi-year follow-up cohorts, representing a solid human evidence level.

It is a licensed biologic prescription medicine, not a peptide supplement, administered under specialist supervision.

How does Laronidase work?

Laronidase is taken up via mannose-6-phosphate receptors into lysosomes, where it supplies the missing alpha-L-iduronidase needed to degrade the glycosaminoglycans dermatan sulfate and heparan sulfate.

Restoring this catabolism reduces glycosaminoglycan storage in liver, spleen, airways and connective tissue, improving somatic (non-neurological) disease burden.

What does the research say about Laronidase?

In the pivotal randomised placebo-controlled phase 3 trial, laronidase improved forced vital capacity and 6-minute walk distance in MPS I. ^[1]
Early open-label treatment reduced hepatosplenomegaly, urinary glycosaminoglycan excretion and improved range of motion and other somatic measures. ^[2]
Benefits in respiratory function, endurance and organ size were maintained over long-term (multi-year) treatment. ^[3]

Clinical research & studies

The references below are the primary sources cited throughout this guide. Each links directly to PubMed or the regulator. Where evidence is preclinical (animal or in-vitro), that is stated rather than implied.

[1] Enzyme replacement therapy for mucopolysaccharidosis I: a randomized, double-blinded, placebo-controlled, multinational study of recombinant human alpha-L-iduronidase (laronidase) — Wraith JE et al., The Journal of Pediatrics 2004. (Randomised double-blind placebo-controlled trial (pivotal phase 3))
[2] Enzyme-replacement therapy in mucopolysaccharidosis I — Kakkis ED et al., The New England Journal of Medicine 2001. (Open-label phase 1/2 study)
[3] Long-term efficacy and safety of laronidase in the treatment of mucopolysaccharidosis I — Clarke LA et al., Pediatrics 2009. (Long-term extension study)
[4] A follow-up study of MPS I patients treated with laronidase enzyme replacement therapy for 6 years — Sifuentes M et al., Molecular Genetics and Metabolism 2007. (Long-term follow-up cohort)
[5] Open issues in Mucopolysaccharidosis type I-Hurler — Parini R et al., Orphanet Journal of Rare Diseases 2017. (Expert review)

Dosing context

This is not medical advice or a usage recommendation. Dosing figures are reported research context only, cited from the published literature.

In clinical use laronidase is given as an intravenous infusion of 0.58 mg/kg once weekly (unlike the every-2-week schedule of imiglucerase and agalsidase beta), with the rate titrated to tolerability.

This is context only and not a dosing recommendation; treatment is initiated and monitored by a metabolic specialist.

Side effects & safety profile

Infusion-associated reactions (flushing, fever, headache, rash, and occasionally bronchospasm) are common and are managed with slower infusion rates and premedication.

Most treated patients develop anti-laronidase IgG antibodies; anaphylactic and other serious hypersensitivity reactions have occurred, so patients are monitored and reactions managed accordingly.

Because the intravenous enzyme does not cross the blood-brain barrier, the central nervous system and cognitive manifestations of severe MPS I (Hurler) are not treated by laronidase.

Stacking & combinations

It is a disease-specific enzyme replacement (sometimes combined with haematopoietic stem cell transplant in severe MPS I under specialist protocols) and is not intended for use with research peptides or supplements.

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Frequently asked questions

It is enzyme replacement therapy for mucopolysaccharidosis type I (MPS I), supplying the missing enzyme alpha-L-iduronidase to break down glycosaminoglycans that otherwise accumulate in tissues.

References

[1] Enzyme replacement therapy for mucopolysaccharidosis I: a randomized, double-blinded, placebo-controlled, multinational study of recombinant human alpha-L-iduronidase (laronidase) — Wraith JE et al., The Journal of Pediatrics 2004. PMID: 15126990. View sourceStudy: Randomised double-blind placebo-controlled trial (pivotal phase 3)Laronidase significantly improved percent predicted forced vital capacity and 6-minute walk distance versus placebo in MPS I.
[2] Enzyme-replacement therapy in mucopolysaccharidosis I — Kakkis ED et al., The New England Journal of Medicine 2001. PMID: 11172140. View sourceStudy: Open-label phase 1/2 studyLaronidase reduced liver and spleen size and urinary glycosaminoglycan levels and improved several somatic clinical measures.
[3] Long-term efficacy and safety of laronidase in the treatment of mucopolysaccharidosis I — Clarke LA et al., Pediatrics 2009. PMID: 19117887. View sourceStudy: Long-term extension studyImprovements in pulmonary function, endurance and hepatomegaly were sustained over extended laronidase treatment.
[4] A follow-up study of MPS I patients treated with laronidase enzyme replacement therapy for 6 years — Sifuentes M et al., Molecular Genetics and Metabolism 2007. PMID: 17011223. View sourceStudy: Long-term follow-up cohortSix years of laronidase maintained reductions in glycosaminoglycan storage and stabilised somatic disease parameters.
[5] Open issues in Mucopolysaccharidosis type I-Hurler — Parini R et al., Orphanet Journal of Rare Diseases 2017. PMID: 28619065. View sourceStudy: Expert reviewReviewed the role and limits of laronidase ERT, including its lack of effect on CNS disease and its use alongside stem cell transplant in Hurler syndrome.

This article is for educational and research purposes only. Peptides discussed here are not approved for human consumption by the FDA, EMA, or equivalent regulators outside of specific clinical contexts. Always consult a licensed medical professional before any therapeutic use.