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UCD Treatments and Therapies in Canada

Urea Cycle Disorders (UCDs) are managed through individualized treatment plans guided by a metabolic clinic. Management focuses on preventing the buildup of ammonia, supporting safe protein intake, and responding quickly to metabolic instability. Treatment varies depending on the specific subtype, age, severity, clinical history, and response to therapy.

Important: Treatment decisions depend on subtype, age, biochemical stability, laboratory monitoring, clinical history, and emergency preparedness. Always follow your clinic's recommendations.

Canada check: Medication authorization, marketed status, and public coverage pathways can change. If you want to confirm whether a medication is currently authorized and marketed in Canada, ask your clinic and verify it in Health Canada's Drug Product Database.

Core treatment approaches

For many individuals with UCDs, treatment includes dietary management, medical formula when indicated, medications to help remove ammonia (sometimes called nitrogen scavengers), amino acid supplementation in some subtypes, and ongoing biochemical monitoring.

Dietary management and medical nutrition

Many individuals with UCDs follow a carefully controlled protein intake to reduce ammonia production. Some may require specialized metabolic formulas, essential amino acid supplements, calorie supplements, or clinic-directed feeding plans to support growth and reduce catabolism. Dietary targets vary by subtype and by individual tolerance.

Related education: Nourish | Low Protein Meal Planning Tools

Ongoing monitoring and long-term care

Regular monitoring of ammonia and related laboratory markers helps clinics assess metabolic stability and adjust treatment plans. Growth, development, nutritional status, liver health, and neurological health are monitored across life stages. Transition to adult care and pregnancy planning require specialized metabolic supervision.

Therapy snapshots by disorder

The same medication may be used across more than one UCD, but the overall treatment plan is not identical. The summaries below are intentionally high-level and should always be individualized by your metabolic clinic.

NAGS deficiency

Foundational care: protein management, formula/supportive nutrition if needed, emergency planning, regular ammonia monitoring
Targeted medication used in Canada: CARBAGLU (carglumic acid)
Other medications sometimes used depending on situation: ammonia scavengers during acute episodes or if additional control is needed
Acute care: hospital treatment for hyperammonemia may include IV therapies and dialysis if severe

NAGS deficiency is the UCD most directly associated with carglumic acid therapy. In some individuals, other ammonia-lowering therapies and dietary restriction may be reduced after stabilization, but this is clinic-directed.

CPS1 deficiency

Foundational care: protein-controlled diet, formula/medical nutrition, sick-day plan, close monitoring
Common chronic medications: RAVICTI (glycerol phenylbutyrate), PHEBURANE (sodium phenylbutyrate), or other clinic-selected nitrogen scavenger strategies
Supplements often considered: citrulline and/or arginine depending on clinic approach and biochemical goals
Acute care: emergency hospital treatment for hyperammonemia
Other option in selected cases: liver transplantation

OTC deficiency

Foundational care: protein-controlled diet, medical nutrition when needed, emergency planning, regular follow-up
Common chronic medications: RAVICTI, PHEBURANE, or other clinic-selected ammonia scavenger strategies
Supplements often considered: citrulline and/or arginine
Acute care: hospital treatment for hyperammonemia during illness, fasting, postpartum periods, or other stressors
Other option in selected cases: liver transplantation

OTC deficiency can present very differently from person to person, including among females, so the same diagnosis does not always mean the same treatment intensity.

ASS1 deficiency (citrullinemia type I)

Foundational care: protein-controlled diet, formula/medical nutrition, monitoring
Common chronic medications: RAVICTI, PHEBURANE, or other ammonia scavenger strategies when needed
Supplement often used: arginine
Acute care: hospital treatment for hyperammonemia
Other option in selected cases: liver transplantation

ASL deficiency (argininosuccinic aciduria)

Foundational care: protein-controlled diet, medical nutrition, emergency planning, regular monitoring
Common chronic medications: RAVICTI, PHEBURANE, or other ammonia scavenger strategies when needed
Supplement often used: arginine
Acute care: hospital treatment for hyperammonemia
Other option in selected cases: liver transplantation

ARG1 deficiency (arginase deficiency / hyperargininemia)

Foundational care: protein-controlled diet, medical nutrition, regular neurological and metabolic follow-up
Chronic medications sometimes used: ammonia scavenger therapy in selected cases if hyperammonemia is part of the picture
Other management priorities: monitoring for mobility, tone, spasticity, developmental, and functional changes
Other option in selected cases: liver transplantation
Worldwide note: Loargys (pegzilarginase) is an ARG1-specific therapy approved in some jurisdictions outside Canada; this page lists it as a worldwide therapy, not a current Canadian marketed product

Medication list: Canada and worldwide context

This section separates medications by how they are generally used. Not every medication applies to every UCD. Some are chronic outpatient therapies, some are hospital therapies, and some are only available in other countries or through non-routine access pathways.

Medications currently authorized and marketed in Canada

RAVICTI (glycerol phenylbutyrate)
Chronic nitrogen scavenger therapy used for long-term ammonia control in UCD patients who cannot be managed by dietary protein restriction and/or amino acid supplementation alone.

PHEBURANE (sodium phenylbutyrate)
Chronic nitrogen scavenger therapy authorized in Canada for certain UCDs. Health Canada materials identify chronic use in CPS, OTC, and ASS-related UCD indications.

CARBAGLU (carglumic acid)
Targeted therapy for NAGS deficiency, including acute and maintenance use as described in Canadian product information.

Clinic-directed supplements and medical products
These can include arginine, citrulline, specialized formula, and calorie support products. Brand names and reimbursement routes vary.

Hospital and emergency medications

Sodium phenylacetate + sodium benzoate (IV)
This is a hospital therapy used in acute hyperammonemia protocols. Families may hear the name AMMONUL from U.S. materials. Canadian hospital use may involve local protocols and/or special access arrangements rather than routine community dispensing.

Other acute treatments
Emergency management can also include IV calories, temporary protein restriction, arginine in selected protocols, and dialysis when hyperammonemia is severe.

Examples of therapies families may hear about outside Canada

OLPRUVA (sodium phenylbutyrate) - a U.S. product/formulation families may see mentioned online
BUPHENYL (sodium phenylbutyrate) - older or other-market formulation name still referenced in some materials
Loargys (pegzilarginase) - ARG1-specific therapy approved in some non-Canadian jurisdictions

Note: A therapy being available in another country does not mean it is routinely authorized, marketed, or funded in Canada. Your clinic can help determine whether a therapy is available here, available through a special process, or only used abroad.

By province: reimbursement and access snapshot

Public drug coverage rules change and can differ by program, age, diagnosis, plan, and prescribing route. The list below is meant as a practical starting point, not a guarantee of funding.

British Columbia

BC has a publicly posted PharmaCare page for sodium phenylbutyrate limited coverage criteria for chronic UCD management. The page notes a 1-year approval period and states Special Authority requests are not required for that listing. Other UCD medications may follow different PharmaCare pathways and should be verified individually.

Ontario

Ontario coverage may be through the Ontario Drug Benefit Formulary and, in some cases, the Exceptional Access Program. Because product routes can change, families should confirm the exact medication and access pathway with their clinic and local pharmacist.

Alberta

Check Alberta's Interactive Drug Benefit List (iDBL) for the exact product and benefit status. Some rare-disease products may require special authorization, non-standard review, or clinic-supported access.

Manitoba

Check Manitoba's eFormulary and Pharmacare resources for the specific product. Coverage may vary between formulary listing, Pharmacare, and other exception or clinic-supported processes.

Quebec

Check RAMQ for current public drug coverage status. Depending on plan type, some individuals may also access coverage through private insurance.

Nova Scotia and other Atlantic provinces

Atlantic public plans may use formulary and exception status processes. Nova Scotia publishes an Exception Status framework and Atlantic review processes that may apply to rare disease drugs.

First Nations and Inuit clients

The federal Non-Insured Health Benefits (NIHB) drug benefit list may be relevant in addition to provincial processes. Your clinic and dispensing pharmacy can help determine whether NIHB, provincial coverage, or both apply.

Practical tip: If you are trying to access RAVICTI, PHEBURANE, CARBAGLU, arginine, citrulline, formula, or low-protein products, ask your clinic which route applies in your province: formulary listing, limited use, Special Authority, Exceptional Access, case-by-case reimbursement, private insurance, NIHB, or hospital-only access.

Emergency management and hyperammonemia

Individuals with UCDs may be at risk of hyperammonemic episodes, particularly during illness, fasting, surgery, postpartum periods, or other physiological stress. Rapid increases in ammonia can lead to neurological symptoms and require urgent hospital care.

What emergency treatment may include

Rapid assessment of ammonia and other labs
IV calories to reduce catabolism
Temporary protein restriction directed by the metabolic team
IV ammonia scavenger therapy in hospital
Arginine in selected protocols
Dialysis when hyperammonemia is severe or not improving fast enough

Emergency letters, sick-day protocols, and clear hospital communication plans are essential parts of care. Families and adult patients should ensure emergency documentation is accessible at all times.

Tip: Ask your clinic if you have an emergency letter and if it needs updating.

Liver transplantation

In some cases, liver transplantation may be considered. Transplant can significantly reduce the risk of recurrent hyperammonemia in certain subtypes, but it is not considered a cure for every issue associated with every UCD and it requires lifelong medical follow-up.

Transplant decisions are complex and individualized. Please refer to your clinic for what might be best for you. For research literature and case discussions, visit the UCD Studies page.

Research, trials, and registries

Looking for research studies, registries, or clinical trials (including studies that may be recruiting)? We track research and studies on our dedicated page:

UCD Studies & Trials UCD Registry

Optional external resources:

Sources and references

External links are shared for education and support. CanPKU+ does not control external content. Always confirm medical guidance and reimbursement details with your metabolic clinic.