Overview of Isavuconazonium

Property	Description
Active Ingredient	Isavuconazonium (Prodrug) -> Isavuconazole (Active Moiety)
Form	Hard capsule, Lyophilized powder for IV injection
Pharmacological Class	Triazole Antifungal
Common Use	Systemic Antifungal Therapy
Origin	Synthetic

What is Isavuconazonium and What Class Does It Belong To?

Isavuconazonium is a prescription-only, synthetic systemic antifungal agent used to combat serious invasive fungal infections throughout the body. It is classified as a second-generation triazole antifungal, belonging to the larger azole pharmacological class. The compound, administered as the isavuconazonium sulfate salt, is recognized for its utility against a wide spectrum of significant invasive mold and yeast infections. This entity is typically reserved for use in adults and certain pediatric patients when dealing with severe internal fungal disease where a broad-spectrum, systemic approach is required.

The Role of Isavuconazonium as a Prodrug

Isavuconazonium is chemically defined as a highly water-soluble prodrug, a differentiating feature that distinguishes it from some earlier azole agents. The molecule itself is biologically inactive until the body rapidly converts it into the actual therapeutic component, the active moiety known as isavuconazole. This conversion supports the drug's predictable absorption profile. The prodrug strategy is advantageous, as it allows for the medicine to be formulated for dual routes of administration: as a solid hard capsule for oral intake, or as a lyophilized powder for preparation as an intravenous (IV) injection.

How Isavuconazonium Works (Fundamental Principle)

The active form, isavuconazole, works by specifically targeting the cells of the invading fungus, interfering with their structural integrity. It achieves this by disrupting the fungus's ability to produce ergosterol, a sterol essential for building and maintaining the fungal cell membrane. This process of ergosterol biosynthesis inhibition is critical because it ultimately destroys the fungal cell structure, underpinning the drug's clinical utility in resolving serious deep-seated infections.

Regulatory References

Isavuconazonium - LiverTox - NIH

What side effects are possible with Isavuconazonium?

Possible Side Effects and Safety Information

Isavuconazonium safety information, as documented in official regulatory documents, details the nature and frequency of possible adverse reactions and specific safety limitations.

Adverse events are classified by their frequency, with many affecting the gastrointestinal tract and liver function. For instance, elevated liver enzymes (AST/ALT) and hypokalemia are listed as very common adverse reactions. Events classified as common include nausea, vomiting, diarrhea, headache, rash, and infusion site reactions when administered intravenously.

Systemic and Cardiac Considerations

The official label groups adverse events according to the affected body system, covering categories such as Hepatobiliary Disorders, Gastrointestinal Disorders, and Cardiac Disorders. A specific and notable characteristic in the cardiovascular safety profile is the drug's association with QTc interval shortening, which distinguishes it from many other agents in the azole class. Serious adverse reactions documented in regulatory sources include the potential for severe hepatotoxicity, anaphylactic reactions, and severe cutaneous reactions.

Safety Restrictions and Special Populations

Specific limitations on use are documented. The medicine is contraindicated in individuals with severe hepatic impairment (Child-Pugh Class C) and when co-administered with strong inducers or inhibitors of the CYP3A4 enzyme system. For patients with renal impairment, no dose adjustment is required, regardless of the severity of the condition. Consistent with the risk of liver events, routine monitoring of liver function tests is a standard safety recommendation in the prescribing information.

Overdose and Emergency Response

Overdose and When to Seek Help

Official regulatory information regarding Isavuconazonium overdose is based on observations from controlled studies using doses higher than the standard therapeutic amount, rather than documented clinical overdose events.

Potential Manifestations and Management

Area of Concern	Official Information from Regulatory Documents
Dose-Related Effect	Studies using supratherapeutic doses (e.g., three times the recommended maintenance dose) showed a concentration-related shortening of the QTc interval (a measure of heart rhythm).
General Symptoms	No specific, unique symptoms of acute overdose are detailed; any observed reactions are generally consistent with known adverse effects.
Required Medical Action	Treatment for overdosage must be supportive and symptomatic as necessary. Standard measures like gastric lavage should be considered in a medical setting.
Elimination	Isavuconazole is highly protein-bound, meaning that removal of the drug by hemodialysis is unlikely to be effective in an overdose situation.

When to Seek Urgent Help

If an overdose is suspected or confirmed, or if a patient experiences any concerning change in health status after administration, immediate medical attention must be sought. Healthcare professionals will initiate supportive treatment and monitoring, which may include observation of the patient's vital signs and clinical status.

Therapeutic Uses of Isavuconazonium

Isavuconazonium is an antifungal agent considered relevant for managing serious invasive fungal infections in adults and certain pediatric patients. The therapy is commonly applied in addressing conditions marked by serious presentations of Invasive Aspergillosis and Invasive Mucormycosis.

Targeting Invasive Mold Disease

This treatment is commonly used to help manage the symptoms related to these deep-seated fungal infections. The therapy plays a role in helping ease the overall symptom load and supports functional stability in areas presenting with organ-specific functional stress, such as the lungs and brain.

Supporting Complex Patient Scenarios

Isavuconazonium is considered relevant across domains where additional symptomatic support is needed, particularly for highly vulnerable patient groups, such as those with hematological malignancies or transplant recipients. Its use may provide supportive relief, assisting with management of symptoms that interfere with daily functioning and helping patients cope more steadily with the difficult episodes of infection.

This medication may be part of symptomatic management when systemic fungal disease is refractory to prior antifungal treatment (salvage therapy) or when patients exhibit intolerance to other antifungal agents. This role is relevant for easing the impact of symptoms by offering an alternative option for symptomatic management.

Quick Fact: Relief for Symptoms related to Systemic Imbalance

Regulatory References

NIH MedlinePlus overview

Eligibility and Restrictions for Use

Eligibility Map: Who can and cannot use Isavuconazonium

Official regulatory documents strictly define who is eligible to use Isavuconazonium. Use is contraindicated (absolutely prohibited) in individuals with familial short QT syndrome or a known hypersensitivity to the medicine. It is also strictly prohibited when co-administered with strong CYP3A4 inhibitors (e.g., ketoconazole) or strong CYP3A4 inducers (e.g., rifampin or St. John's wort).

Eligibility Status by Population

Adults are eligible. For pediatric patients, use is conditional: the injection is approved for those 1 year of age and older, while capsules are limited to children 6 years of age and older who weigh 16 kg or more. Use is not established below these minimum thresholds.
Patients with severe hepatic impairment (Child-Pugh C) are officially not recommended to use the drug, though use in all forms of renal impairment is generally allowed without dose adjustment.
Use is generally prohibited during pregnancy due to the risk of fetal harm, and females of reproductive potential are required to use effective contraception during therapy. Use is also not recommended while breastfeeding.

Connection to the Overall Eligibility Profile

The regulatory eligibility profile is structured around identifying absolute contraindications (heart condition, specific drug combinations) and defining conditional use based on age, weight, and the functional status of the liver. Every statement regarding who can and cannot use the medicine is based solely on regulatory labeling.

What should I know about interactions with other medicines?

The active substance of isavuconazonium, isavuconazole, is a substrate and moderate inhibitor of the cytochrome P450 enzyme CYP3A4/5, as well as a mild inhibitor of P-glycoprotein (P-gp) and an inducer of CYP2B6. These metabolic activities define its clinically significant drug interaction profile.

Contraindicated Combinations (Do Not Combine)

Co-administration with the following drug categories is contraindicated due to the high risk of a clinically significant change in isavuconazole exposure:

Category	Examples	Basis of Interaction
Strong CYP3A4 Inhibitors	Ketoconazole	Significantly increases isavuconazole levels
Strong CYP3A4/5 Inducers	Rifampin, Phenytoin, Carbamazepine, St. John's wort	Significantly decreases isavuconazole levels

Combinations Requiring Caution and Monitoring

Isavuconazole may increase the concentration of medicines that are substrates of CYP3A4 or P-gp. Caution and potentially dose adjustments are required for:

CYP3A4 Substrates with Narrow Therapeutic Index: Immunosuppressants such as Tacrolimus, Sirolimus, and Cyclosporine. Therapeutic Drug Monitoring (TDM) and dose adjustment of the immunosuppressant are necessary.
P-gp Substrates: Medicines like Digoxin; close monitoring and dose titration of the substrate drug may be needed.
Other Noteworthy Interactions: Concomitant use with Vincristine should be avoided due to the predicted increase in vincristine exposure, which may increase the risk of adverse reactions. The use of strong CYP3A4/5 inhibitors like Lopinavir/Ritonavir may increase isavuconazole exposure, requiring caution though dose adjustment for isavuconazole is typically not necessary.

Mechanism of Action

Prodrug Activation and Target Availability

The administered compound, isavuconazonium, is chemically an inactive prodrug. It is rapidly converted into the active moiety, isavuconazole, through esterase-mediated hydrolysis within the systemic circulation. This chemical transformation is necessary to ensure a predictable and sufficient systemic exposure of the active drug, facilitating its engagement with its specific molecular target inside the fungal cell.

Specific Inhibition of Fungal Cell Structure

The active moiety, isavuconazole, exerts its effect by selectively targeting the fungal enzyme lanosterol 14-alpha-demethylase (CYP51). By inhibiting this enzyme, the drug blocks a critical step in the synthesis of ergosterol, a sterol essential for the structural integrity and function of the fungal cell membrane. This blockade simultaneously leads to the accumulation of toxic methylated sterol precursors within the fungal cell.

Pathogen Breakdown and Viability Loss

The resulting depletion of essential ergosterol, combined with the buildup of toxic sterols, fundamentally compromises the integrity and permeability of the fungal cell membrane. This leads to the leakage of vital intracellular components, which ultimately causes the destruction or permanent suppression of the fungal pathogen. This mechanism establishes a targeted, pathogen-specific effect.

Dosage and Administration Information

How Isavuconazonium is Used: Official Administration Guidelines

Isavuconazonium is administered according to a highly specific, standardized protocol. The medicine is available for both Intravenous (IV) infusion and oral administration as hard capsules. This dual-route availability allows for flexibility, and patients can transition between the IV and oral forms without needing a new loading dose due to the drug’s bioequivalence.

Treatment follows a precise two-phase dosing schedule.

Official Dosing Sequence

Phase	Dose	Frequency
Loading	372 mg isavuconazonium sulfate (equivalent to 200 mg isavuconazole)	Every 8 hours for 6 doses (48 hours)
Maintenance	372 mg isavuconazonium sulfate (equivalent to 200 mg isavuconazole)	Once daily (qDay)

The maintenance phase begins 12 to 24 hours after the last loading dose. The overall duration of therapy is determined by the patient's clinical response.

Administration Requirements

Oral capsules may be taken with or without food; however, they must be swallowed whole and must not be chewed, crushed, dissolved, or opened. For the IV route, the diluted solution must be infused over a minimum of 1 hour and requires administration through an in-line filter. The IV form must not be given as a rapid bolus injection.

No dose adjustment is required for adults with mild to moderate hepatic impairment or for any degree of renal impairment. Dosing for pediatric patients is determined by weight, with the maximum individual dose not exceeding 372 mg.

Recent Clinical Evidence

Research evidence / Overview of studies for Isavuconazonium

Evidence for Use in Invasive Aspergillosis

Research for Invasive Aspergillosis (IA) primarily involved a large, controlled study comparing Isavuconazonium to Voriconazole. This study examined adult patients with confirmed or probable IA, most of whom had underlying hematological malignancies or had undergone HSCT. The main goal was to measure all-cause mortality at Day 42. Findings describe patterns where mortality rates for patients receiving Isavuconazonium were assessed against the same outcome for the comparator drug. Results apply only to the studied populations; evidence for patients without underlying hematological conditions and long-term effects beyond the initial 84-day treatment period are not fully established.

Evidence for Use in Invasive Mucormycosis

Research for Invasive Mucormycosis (IM) was examined in a small, non-comparative trial (the VITAL study) that monitored outcomes up to 180 days. This research was studied for patients receiving treatment for the first time or those who were refractory to prior antifungal treatment or intolerant to other agents. The core limitation is the non-comparative design and small sample size, which means comparative evidence is lacking, and certainty regarding its findings appears to remain low.

Evidence in Special Populations

Research involving pediatric patients (ages 1 to under 18) focused on open-label Phase 1/2 studies. These trials primarily established consistent drug exposure (pharmacokinetics) and assessed short-term responses, such as all-cause case fatality at Day 42. However, sample sizes were modest, and comparative evidence is lacking regarding standard care, meaning data are still emerging and long-term outcomes are not fully established for children.

What is Still Uncertain About Isavuconazonium

The current evidence base has several structural limitations. Comparative evidence is lacking in the pivotal trial for Mucormycosis. Furthermore, data for certain groups remain insufficient, particularly for patients with severe kidney or liver dysfunction, as they were often excluded from the main studies. Research continues to explore these remaining questions.

Key Studies & References

Study Details | NCT03816176 | A Study to Evaluate Isavuconazonium Sulfate for the Treatment of Invasive Aspergillosis (IA) or Invasive Mucormycosis (IM) in Pediatric Participants

Frequently Asked Questions (FAQ)

Common questions about Isavuconazonium (FAQ)

Q: What should I avoid eating or drinking while taking Isavuconazonium?

Official product information advises strictly avoiding strong inhibitors of the CYP3A4 enzyme system. This includes the herbal supplement St. John's wort, which is listed as contraindicated. While the medicine can be taken with or without food, patients are advised to consult with a healthcare professional about all foods, drinks, and supplements, such as grapefruit juice, that might interfere with how the body processes the medicine.

Q: Can elderly patients use Isavuconazonium?

According to official guidelines, clinical studies for Isavuconazonium included patients who were 65 years of age and older. No specific dose adjustment is required for adult patients based only on their age or the presence of renal impairment. The determination of appropriate treatment remains with the healthcare provider and is based on the patient's full clinical picture.

Q: Is the IV form of Isavuconazonium different from the pill form?

Yes, the medicine is supplied in two different forms: hard capsules for swallowing and a lyophilized powder that is prepared for intravenous (IV) injection. These are distinct physical forms with different administration requirements, such as the IV form needing an in-line filter. Official documents state they are bioequivalent, meaning they provide the same amount of active medicine to the body, allowing patients to switch forms without needing a new loading dose.

Q: Can you take vitamins or supplements with Isavuconazonium?

Regulatory safety information strictly contraindicates the use of certain supplements, specifically listing the strong CYP3A4 inducer St. John's wort as prohibited. Since the active medicine interacts with metabolic enzymes in the body, regulatory information indicates that all vitamins, nutritional supplements, and herbal products should be discussed with a healthcare professional.

Q: Does Isavuconazonium interact with grapefruit juice?

Yes, official product information strictly contraindicates the medicine's use with strong CYP3A4 inhibitors. Since grapefruit juice is known to be a strong inhibitor of this specific enzyme system, avoidance of its consumption is advised based on the risk of interaction while undergoing treatment.

Q: Does Isavuconazonium cause hair loss?

According to regulatory documents detailing possible side effects, hair loss (alopecia) has been reported. This reaction is classified as uncommon, meaning it is noted in a small percentage of patients.

Q: Is it normal to feel tired while taking Isavuconazonium?

Official product information lists unusual tiredness or weakness (fatigue) as a common side effect experienced by patients in clinical studies. If any side effect, including fatigue, is severe or concerning, consultation with a healthcare professional is appropriate.

Q: Does Isavuconazonium interact with blood pressure medicine?

Yes, the active drug is a known inhibitor of the CYP3A4 enzyme system, which is involved in processing many other medicines, including some blood pressure medications. Using the medicine with certain blood pressure drugs, such as specific calcium channel blockers, may require caution and monitoring, as indicated in the product label.

Q: What happens if I miss a dose of Isavuconazonium?

The official patient information advises that if a dose is missed, the patient should contact a doctor or healthcare provider for specific instructions. The dose timing schedule is precise, and guidance from a professional is needed to ensure the correct drug level is maintained in the system.

Q: Is Isavuconazonium used for treating Valley Fever?

According to regulatory documents, the approved indications are for the treatment of invasive aspergillosis and invasive mucormycosis. The medicine is not officially indicated for the treatment of Valley Fever (Coccidioidomycosis) or similar fungal infections not listed on the official product label.

Q: Does Isavuconazonium affect birth control pills?

Yes, official documents state that the active drug may increase the concentration of certain oral contraceptives in the body. Furthermore, females of reproductive potential are instructed by the regulatory label to use effective contraception during treatment and for 28 days after the final dose is administered.

Q: How long does Isavuconazonium stay in your system?

The administered compound (the prodrug) is quickly converted into the active medicine, isavuconazole. The active medicine has a long terminal elimination half-life, which is the amount of time it takes for half the drug to be eliminated from the body. This characteristic means the active drug remains present in the body for an extended period after the final dose.

Q: Are there different brand names for Isavuconazonium?

Yes, the International Nonproprietary Name (INN) for the drug is Isavuconazonium, and it is marketed under the brand name Cresemba.

Q: Does Isavuconazonium cause drowsiness?

Official safety information confirms that drowsiness (somnolence) is a common side effect reported by patients in clinical trials.

Q: Is a metallic taste in the mouth common with Isavuconazonium?

A taste disorder (dysgeusia), which may include a metallic taste in the mouth, is listed as an uncommon side effect in regulatory safety documents. Uncommon means this effect is noted in less than 1% of patients.

Q: Can someone with diabetes take Isavuconazonium?

The official safety information reports the adverse reaction of low blood sugar (hypoglycemia). While there is no specific contraindication based on diabetes, individuals with pre-existing conditions, such as diabetes, are advised to discuss their use of the medicine with a healthcare provider.

Q: Is Isavuconazonium used to prevent infections in certain patients?

According to regulatory documents detailing the approved uses, the medicine is indicated for the treatment of specified invasive fungal infections. The official label does not currently list a specific indication for prophylaxis (prevention) of these infections.

How should Isavuconazonium be stored and disposed of?

Storage and Handling of Isavuconazonium

Storage requirements for isavuconazonium sulfate are defined by the formulation.

Oral Capsules

Isavuconazonium capsules must be stored at Controlled Room Temperature (20 C to 25 C). They must be kept in the original packaging to protect the medicine from moisture and direct light. The capsules should not be stored in pill organizers.

Injection Vials and Solutions

Unreconstituted vials of the powder for injection must be stored under refrigeration (2 C to 8 C). Once reconstituted and diluted, the infusion solution is time-sensitive: administration must be completed within 6 hours at room temperature or within 24 hours if refrigerated. The diluted solution must not be frozen.

Safety and Disposal

All forms of the medication must be stored out of the sight and reach of children. Unused or expired isavuconazonium must be disposed of in accordance with local requirements. The medicine should not be discarded into the environment or wastewater.

Isavuconazonium