Ivacaftor ELPEN: Uses, Dosage & Side Effects

What Is Ivacaftor ELPEN and What Is It Used For?

Ivacaftor ELPEN contains the active substance ivacaftor, which belongs to a class of medications known as CFTR potentiators. Cystic fibrosis (CF) is a progressive, life-limiting genetic disease caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein. The CFTR protein functions as a chloride and bicarbonate channel on the surface of epithelial cells, and its proper function is essential for maintaining the correct composition and volume of fluid on mucosal surfaces throughout the body, including the airways, gastrointestinal tract, pancreas, and sweat glands.

In cystic fibrosis, mutations in the CFTR gene lead to either absent, misfolded, or dysfunctional CFTR protein. There are more than 2,000 known CFTR mutations, which have been classified into six classes based on the type of defect they cause in CFTR protein production, processing, or function. Ivacaftor specifically targets Class III gating mutations, in which the CFTR protein reaches the cell surface but has a severely reduced channel-open probability. The most common gating mutation is G551D, which is found in approximately 4–5% of CF patients worldwide. Other responsive gating mutations include G1244E, G1349D, G178R, G551S, S1251N, S1255P, S549N, and S549R.

The mechanism of action of ivacaftor is fundamentally different from CFTR correctors (such as lumacaftor, tezacaftor, or elexacaftor), which address defects in protein folding and trafficking. Instead, ivacaftor acts as a potentiator: it binds directly to the CFTR protein at the cell membrane and increases the time the channel spends in the open configuration. In vitro studies have shown that ivacaftor increases the channel-open probability of the G551D-CFTR protein to near-normal levels, restoring chloride transport to approximately 35–50% of normal CFTR function. This level of restoration is clinically meaningful and sufficient to produce substantial improvements in lung function, nutritional status, and quality of life.

The pivotal clinical trial for ivacaftor in patients with the G551D mutation was the STRIVE study (Study of VX-770 in CF Patients with G551D Mutation Aged 12 Years and Older), a phase III, randomized, double-blind, placebo-controlled trial involving 161 patients aged 12 years and older. After 24 weeks of treatment, patients receiving ivacaftor 150 mg twice daily experienced a mean absolute improvement in percent predicted forced expiratory volume in 1 second (ppFEV₁) of 10.6 percentage points compared with placebo (p < 0.001). This improvement was rapid, with significant effects observed as early as Day 15, and was sustained through 48 weeks of treatment. Patients treated with ivacaftor also experienced a mean reduction in sweat chloride concentration of 48.1 mmol/L compared with placebo, bringing many patients’ sweat chloride values below the diagnostic threshold for CF.

Additional clinical benefits demonstrated in the STRIVE and subsequent ENVISION study (which enrolled patients aged 6–11 years with the G551D mutation) included significant weight gain, reduced risk of pulmonary exacerbations (a 55% reduction in the rate of pulmonary exacerbations compared with placebo), and improvements in patient-reported respiratory symptoms as measured by the Cystic Fibrosis Questionnaire-Revised (CFQ-R). Long-term follow-up data from open-label extension studies (PERSIST) demonstrated that the benefits of ivacaftor treatment were sustained for at least 144 weeks, with continued improvements in FEV₁ and maintained reductions in sweat chloride.

Ivacaftor was originally developed and marketed by Vertex Pharmaceuticals under the brand name Kalydeco. It was first approved by the FDA in January 2012 for patients aged 6 years and older with the G551D-CFTR mutation, making it the first medication to treat the underlying cause of CF rather than its symptoms. The EMA granted marketing authorization in July 2012. Ivacaftor ELPEN is a generic formulation manufactured by ELPEN Pharmaceutical Co. Inc. that contains the same active substance and is bioequivalent to the originator product.

What Should You Know Before Taking Ivacaftor ELPEN?

Contraindications

The primary contraindication to Ivacaftor ELPEN is hypersensitivity (allergy) to ivacaftor or to any of the excipients in the formulation. Patients with a known allergy to any component of the tablet should not take this medication. While there are no other absolute contraindications listed, several clinical situations require special caution and potentially warrant avoidance of ivacaftor or dose modification.

Patients who are homozygous for the F508del-CFTR mutation should not be treated with ivacaftor monotherapy, as clinical trials have demonstrated no meaningful efficacy in this population. The F508del mutation causes a folding and trafficking defect that prevents the CFTR protein from reaching the cell surface in sufficient quantities; since ivacaftor can only potentiate CFTR protein that is already at the cell surface, it cannot produce a clinical benefit in F508del-homozygous patients without the addition of a CFTR corrector.

Warnings and Precautions

Before starting Ivacaftor ELPEN, discuss the following with your healthcare provider:

• Liver disease: Patients with moderate hepatic impairment (Child-Pugh Class B) should receive a reduced dose of ivacaftor (150 mg once daily instead of twice daily). There is no clinical experience in patients with severe hepatic impairment (Child-Pugh Class C), and ivacaftor should be used in these patients only if the benefits clearly outweigh the risks, at a starting dose of 150 mg every other day or less frequently. Liver function tests must be monitored more frequently in patients with pre-existing liver disease.
• Kidney disease: No dose adjustment is necessary for patients with mild to moderate renal impairment. Caution is advised in patients with severe renal impairment (creatinine clearance ≤30 mL/min) or end-stage renal disease, as ivacaftor has not been studied in these populations.
• Cataracts: Cases of non-congenital lens opacities (cataracts) without impact on vision have been reported in pediatric patients treated with ivacaftor and ivacaftor-containing regimens. While a causal relationship has not been established, baseline and follow-up ophthalmological examinations are recommended in pediatric patients.
• Concomitant medications: Ivacaftor is metabolized extensively by CYP3A enzymes, and co-administration with strong CYP3A inhibitors (such as ketoconazole, itraconazole, posaconazole, voriconazole, or clarithromycin) significantly increases ivacaftor exposure, requiring dose reduction. Co-administration with strong CYP3A inducers (such as rifampicin, rifabutin, phenobarbital, carbamazepine, phenytoin, or St. John’s Wort) substantially reduces ivacaftor exposure and is not recommended.

Pregnancy and Breastfeeding

There are limited data on the use of ivacaftor in pregnant women. Animal reproductive studies did not reveal any evidence of teratogenicity or harm to the fetus at exposures up to approximately 5 times the maximum recommended human dose based on area under the curve (AUC). However, as a precaution, Ivacaftor ELPEN should only be used during pregnancy if the potential benefit to the mother justifies the potential risk to the fetus. Women who are pregnant or planning to become pregnant should discuss the risks and benefits of continued ivacaftor therapy with their healthcare provider and their CF specialist team.

It is not known whether ivacaftor or its metabolites are excreted in human breast milk. In animal studies, ivacaftor was present in the milk of lactating rats. A decision must be made whether to discontinue breastfeeding or to discontinue ivacaftor treatment, taking into account the benefit of breastfeeding for the child and the benefit of treatment for the mother. Given the importance of CFTR modulator therapy in maintaining lung function and overall health in CF patients, many specialist centers recommend continuing ivacaftor during breastfeeding while monitoring the infant for any adverse effects.

How Does Ivacaftor ELPEN Interact with Other Drugs?

Understanding drug interactions with Ivacaftor ELPEN is critically important because ivacaftor is both a substrate and an inhibitor of the cytochrome P450 3A (CYP3A) enzyme system, as well as a potential inhibitor of P-glycoprotein (P-gp). These pharmacokinetic properties create several clinically significant interactions that can either increase ivacaftor toxicity or reduce its therapeutic effectiveness.

Major Interactions

The following drug interactions are considered major and require either dose adjustment, close monitoring, or avoidance of concomitant use:

Minor Interactions

Ivacaftor is itself a weak inhibitor of CYP3A and a potential inhibitor of P-glycoprotein (P-gp). This means that ivacaftor can modestly increase the systemic exposure of drugs that are metabolized by these pathways:

• Midazolam: Co-administration with ivacaftor increased midazolam AUC by approximately 1.5-fold. Patients using benzodiazepines metabolized by CYP3A (such as midazolam or triazolam) should be monitored for enhanced sedative effects.
• Digoxin: Co-administration increased digoxin AUC by approximately 1.3-fold. Digoxin has a narrow therapeutic index, and patients taking digoxin concurrently with ivacaftor should have serum digoxin levels monitored and dose adjusted as needed.
• Ciclosporin and Tacrolimus: Both are narrow therapeutic index drugs that are CYP3A and P-gp substrates. Monitor blood levels and adjust doses as necessary when co-administering with ivacaftor.
• Hormonal contraceptives: Ivacaftor did not affect the pharmacokinetics of oral contraceptives containing ethinylestradiol and norethisterone in a clinical study. No dose adjustment is required.
• Warfarin: While no formal interaction study has been conducted, CYP3A-mediated interactions could theoretically affect warfarin metabolism. INR monitoring is advised during co-administration.

What Is the Correct Dosage of Ivacaftor ELPEN?

Ivacaftor ELPEN should only be prescribed by physicians with experience in the treatment of cystic fibrosis. A CFTR genotyping test using a validated mutation detection method should be performed prior to initiating treatment to confirm the presence of at least one CFTR gating mutation that is responsive to ivacaftor potentiation.

Adults

The tablets must be taken with fat-containing food to ensure adequate absorption. Examples of fat-containing foods include eggs, butter, peanut butter, cheese pizza, whole-milk dairy products, and avocado. Studies have shown that administration with fat-containing food increases ivacaftor bioavailability by approximately 2.5–4-fold compared to fasting conditions. Taking ivacaftor without food significantly reduces its absorption and may compromise therapeutic efficacy.

Children

For children aged 6 years and older who weigh less than 25 kg, lower-strength formulations (granules or lower-dose tablets) are available from the originator product. Ivacaftor ELPEN 150 mg tablets should only be used in children weighing 25 kg or more. Safety and efficacy of ivacaftor have not been established in children younger than 4 months of age.

Elderly

No specific dose adjustment is required for elderly patients based on age alone. However, since renal function may decline with age, caution is advised in elderly patients with impaired kidney function. Liver function should also be monitored as recommended for all patients. Clinical data in patients aged 65 years and older are limited, as cystic fibrosis historically has been associated with reduced life expectancy, though survival has improved dramatically with modern therapies including CFTR modulators.

Dose Adjustments for Hepatic Impairment and Drug Interactions

Missed Dose

If a dose of Ivacaftor ELPEN is missed within 6 hours of the scheduled time, the patient should take the dose as soon as possible with fat-containing food, and then resume the normal dosing schedule. If more than 6 hours have passed since the missed dose, the patient should skip the missed dose entirely and take the next dose at the regularly scheduled time. Patients should not double the dose to make up for a missed one, as this increases the risk of adverse effects without providing additional therapeutic benefit.

Overdose

There is no specific antidote for ivacaftor overdose. In the event of an overdose, the patient should be monitored for adverse effects and appropriate supportive treatment should be provided. Symptoms of overdose may include enhanced pharmacological effects such as dizziness, headache, and gastrointestinal disturbances. In clinical studies, single doses of up to 450 mg and multiple doses of up to 250 mg every 12 hours were administered without dose-limiting toxicity. The management of overdose should include general supportive measures, including monitoring of vital signs and observation of the clinical status of the patient. As ivacaftor is highly protein-bound (approximately 99%), hemodialysis is unlikely to be effective in removing ivacaftor from the circulation.

What Are the Side Effects of Ivacaftor ELPEN?

Like all medications, Ivacaftor ELPEN can cause side effects, although not everybody experiences them. The safety profile of ivacaftor has been well characterized through extensive clinical trials involving more than 1,000 patients and through long-term post-marketing surveillance. The following side effects have been reported, organized by frequency category according to the Medical Dictionary for Regulatory Activities (MedDRA) convention:

Liver Effects in Detail

Elevated transaminases (ALT and AST) are among the most clinically significant side effects of ivacaftor. In clinical trials, increases in transaminases greater than 3 times the upper limit of normal occurred in approximately 5–6% of ivacaftor-treated patients compared with approximately 3% in the placebo group. Increases greater than 5 times the upper limit of normal were reported in approximately 3% of ivacaftor-treated patients. In most cases, transaminase elevations resolved with dose reduction or temporary interruption of treatment, and treatment could be successfully resumed.

The mechanism of ivacaftor-related hepatotoxicity is not fully understood. It may be related to direct hepatocellular toxicity, immune-mediated injury, or improved CFTR function in biliary epithelial cells leading to changes in bile composition and flow. Patients with pre-existing liver disease, including CF-related liver disease (which affects approximately 30–40% of CF patients to some degree), may be at increased risk and require more vigilant monitoring.

Ear-Related Effects

Ear-related side effects (ear discomfort, tinnitus, tympanic membrane hyperemia, and vestibular disorders) have been reported more frequently with ivacaftor than with placebo. These effects may be related to changes in chloride and fluid transport in the middle ear and inner ear epithelium as CFTR function improves. Most ear-related side effects are mild and self-limiting. Patients who develop persistent ear symptoms should be evaluated by an otolaryngologist.

How Should You Store Ivacaftor ELPEN?

Proper storage of Ivacaftor ELPEN is important to maintain the tablet’s integrity and therapeutic effectiveness throughout its shelf life. The following storage recommendations should be followed:

• Temperature: Store below 30°C (86°F). Do not refrigerate or freeze the tablets. Avoid exposing the tablets to excessive heat or direct sunlight, which may degrade the active substance.
• Moisture protection: Keep the tablets in the original blister packaging until immediately before use. Ivacaftor is sensitive to moisture, and removing tablets from the blister pack prematurely may compromise their stability.
• Child safety: Store the medication in a location that is out of the reach and sight of children. Ivacaftor is a potent medication, and accidental ingestion by a child could cause adverse effects.
• Expiry date: Do not use Ivacaftor ELPEN after the expiry date stated on the packaging (Exp.). The expiry date refers to the last day of the stated month.
• Disposal: Do not dispose of unused or expired tablets via wastewater or household waste. Return them to your pharmacist for proper disposal in accordance with local environmental regulations. This helps protect the environment from pharmaceutical contamination.

When traveling with Ivacaftor ELPEN, keep the medication in its original packaging and ensure it is not exposed to extreme temperatures. Carry the medication in hand luggage when flying rather than in checked baggage, where temperature conditions in the cargo hold may be unpredictable. If you are traveling across time zones, consult your CF specialist about the best strategy for maintaining the twice-daily dosing schedule.

What Does Ivacaftor ELPEN Contain?

Active Ingredient

Each film-coated tablet contains 150 mg of ivacaftor. Ivacaftor (chemical name: N-(2,4-di-tert-butyl-5-hydroxyphenyl)-1,4-dihydro-4-oxoquinoline-3-carboxamide) has a molecular formula of C₂₄H₂₈N₂O₃ and a molecular weight of 392.49 g/mol. It is a white to off-white crystalline powder that is practically insoluble in water, which is why it must be taken with fat-containing food to ensure adequate dissolution and absorption in the gastrointestinal tract.

Inactive Ingredients (Excipients)

The inactive ingredients in Ivacaftor ELPEN 150 mg film-coated tablets may include:

• Tablet core: Microcrystalline cellulose, lactose monohydrate, hypromellose acetate succinate, croscarmellose sodium, sodium lauryl sulfate, colloidal silicon dioxide, and magnesium stearate.
• Film coating: Polyvinyl alcohol, titanium dioxide (E171), macrogol (polyethylene glycol), talc, and indigo carmine aluminium lake (E132).

Patients with known allergies or intolerances to any of these excipients should inform their healthcare provider before starting treatment. Of particular note, the tablets contain lactose monohydrate; patients with rare hereditary problems of galactose intolerance, total lactase deficiency, or glucose-galactose malabsorption should not take this medication. The film coating contains titanium dioxide (E171), which is used as a white colorant in pharmaceutical products.