Tolvaptan Medications

Tolvaptan is a vasopressin antagonist medication used to treat low sodium levels (hyponatremia) by increasing water excretion through the kidneys.

Samsca

Tolvaptan

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15 | 30mg

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About Tolvaptan Compound

Tolvaptan is a selective vasopressin V2-receptor antagonist that reduces water reabsorption in the kidney and, in certain kidney diseases, slows cyst growth. It is classified as a “vaptan” and is available worldwide under brand names such as Samsca and Jynarque, as well as in generic form. The drug received its first regulatory approval in 2012 for the treatment of clinically significant hyponatremia, and later gained indication for autosomal dominant polycystic kidney disease (ADPKD). By blocking the action of antidiuretic hormone, tolvaptan promotes excretion of free water without major loss of electrolytes-a process called aquaresis. Clinicians also prescribe it off-label for severe cases of syndrome of inappropriate antidiuretic hormone secretion (SIADH) when standard therapies fail. Its therapeutic profile, dosing flexibility, and oral formulation have made it a common option in our online pharmacy for patients who need rapid correction of low sodium or a disease-modifying therapy for ADPKD.

What is Tolvaptan?

Tolvaptan belongs to the class of vasopressin V2-receptor antagonists, commonly referred to as “vaptans.” The Singapore Health Sciences Authority (HSA) listed the drug on its approved medicines register for hyponatremia in 2014, and it has since been incorporated into the national formulary for adult patients with serum sodium ≤ 125 mmol/L who require active correction. In 2020 the HSA also acknowledged its indication for ADPKD, aligning with the United States Food and Drug Administration (FDA) which granted approval for this use in 2018.

At the molecular level, tolvaptan binds competitively to the V2 receptors located on the basolateral membrane of collecting-duct cells. This prevents arginine-vasopressin (AVP) from stimulating the cyclic-AMP pathway that normally inserts aquaporin-2 (AQP2) water channels into the apical membrane. Without AQP2, water remains in the tubular lumen and is eliminated as dilute urine. In ADPKD, reduced intracellular cAMP also dampens epithelial cell proliferation and fluid secretion, thereby slowing cyst enlargement.

Both branded products (Samsca®, Jynarque®) and generic formulations are stocked by our online pharmacy, offering patients the same active ingredient at differing price points.

How Tolvaptan Works

Mechanism of Action

Tolvaptan’s selective antagonism of V2 receptors disrupts the AVP-cAMP-AQP2 cascade. By blocking this pathway, the drug creates an “aquaresis” effect: free water is expelled while sodium and potassium remain largely unchanged. In ADPKD, the same blockade curtails cAMP-driven cystic epithelial growth, translating into a measurable reduction in total kidney volume over time.

Therapeutic Effects

The immediate clinical benefit of aquaresis is a rise in serum sodium concentration, typically 3-6 mmol/L within the first 24 hours of therapy. For patients with ADPKD, long-term use has been shown to lower the rate of kidney-function decline, as measured by the estimated glomerular filtration rate (eGFR). Both outcomes stem directly from the drug’s ability to limit water reabsorption and to reduce cAMP-mediated cellular proliferation.

Onset and Duration

Aquaretic activity appears within 2-4 hours after the first oral dose, peaks around 12 hours, and persists for roughly 24 hours because the drug’s half-life is about 12 hours. Steady-state plasma concentrations are reached after 3-5 days of once-daily dosing. Clinicians monitor serum sodium at baseline, then at 6-hour and 24-hour intervals during the initial titration phase to avoid overly rapid correction.

Approved Uses and Applications

Approved Indications

Hyponatremia (euvolemic or hypervolemic): For adults with serum sodium ≤ 125 mmol/L where fluid restriction is insufficient or impractical. The HSA and FDA label the drug for “clinically significant” hyponatremia associated with SIADH, heart failure, or cirrhosis.
Autosomal Dominant Polycystic Kidney Disease (ADPKD): For adults at risk of rapidly progressive disease (eGFR ≥ 30 mL/min/1.73 m²) who have confirmed PKD1 or PKD2 mutations. The FDA’s pivotal TEMPO 3:4 trial demonstrated a 30 % reduction in the increase of total kidney volume over three years.

Off-Label Uses

Tolvaptan is sometimes employed for refractory SIADH when conventional demeclocycline or oral urea fail, and for selected cases of severe heart-failure-related hyponatremia where rapid correction is essential. These applications are not formally approved by the HSA; clinicians must weigh the limited evidence and obtain informed consent.

Clinical Efficacy

In the TEMPO 3:4 trial (published in The New England Journal of Medicine), patients receiving tolvaptan experienced a mean annual eGFR decline of 2.8 mL/min/1.73 m² versus 3.9 mL/min/1.73 m² in the placebo group, a statistically significant difference (p < 0.001). For hyponatremia, a meta-analysis in Lancet Diabetes & Endocrinology reported that tolvaptan raised serum sodium by an average of 5.5 mmol/L within 24 hours, outpacing fluid restriction alone (mean difference = 4.2 mmol/L).

Buying Tolvaptan from Our Online Pharmacy

Why Choose Our Service

Access to tolvaptan can be hindered by limited stock in brick-and-mortar outlets or by insurance formularies that restrict certain brands. Our online pharmacy bridges this gap by sourcing licensed shipments directly from WHO-GMP-certified manufacturers. You receive a secure, discreet package while retaining control over pricing and delivery speed.

Brand Names and Generic Options

Samsca® - tablet formulation, 15 mg and 30 mg strengths.
Jynarque® - marketed specifically for ADPKD, 45 mg and 60 mg tablets.
Generic Tolvaptan - chemically identical to the branded products, offered in 15 mg, 30 mg and 60 mg tablets at up to 35 % lower cost.

Quality & Safety

Our service works with licensed international pharmacies that operate under strict regulatory frameworks, ensuring each batch meets the standards set by the HSA and the World Health Organization.

Pricing & Access

The generic version typically costs SGD 45 per 30-day supply, compared with SGD 78 for the branded brand. All repeat orders qualify for a lifetime 10 % discount, making long-term therapy financially sustainable.

Discreet Delivery

Express shipping arrives within approximately 7 days, while the standard option reaches you in about 3 weeks. Each parcel is wrapped in unbranded, tamper-evident material to protect privacy.

Dosing, Formulations & Administration

Available Formulations

Tolvaptan is supplied as oral tablets in 15 mg, 30 mg, 45 mg and 60 mg strengths. The tablets are film-coated, water-soluble, and designed for whole-pill ingestion.

Typical Dosing Ranges

Hyponatremia: Clinicians frequently start with 15 mg once daily, increasing to 30 mg after 24 hours if sodium rise is inadequate and the patient tolerates the medication. Some protocols allow titration up to 60 mg per day, divided into two doses, to achieve target sodium levels.
ADPKD: The recommended regimen begins with 45 mg in the morning and 45 mg in the afternoon (total 90 mg/day). After two weeks, the dose may be escalated to 60 mg twice daily (120 mg/day) provided liver-function tests remain within acceptable limits.

These examples illustrate typical practice; the exact regimen must be individualized by a qualified healthcare provider.

Administration Guidelines

Tolvaptan should be taken with food to enhance absorption and reduce the risk of gastrointestinal upset. Patients are advised to maintain adequate hydration, avoiding excessive fluid restriction that could precipitate rapid sodium shifts. Missed doses should be taken as soon as remembered unless the next scheduled dose is within 4 hours, in which case the missed dose is skipped to avoid double-dosing.

A healthcare professional must determine the precise dose based on laboratory values, disease severity, and other medications.

Safety Profile & Considerations

Common Side Effects

Thirst and polyuria: Reported in >10 % of participants, reflecting the drug’s aquaretic action.
Elevated liver enzymes (ALT/AST): Observed in approximately 8 % of ADPKD patients; regular monitoring is mandatory.
Dry mouth: Occurs in 6-9 % of users, often mild and self-limiting.
Nausea: Documented in 5-7 % of trial participants.

Serious Adverse Events

Hepatotoxicity: Rare cases of severe liver injury (including jaundice) have led to treatment discontinuation. Prompt evaluation of liver-function tests is required if ALT exceeds three times the upper limit of normal.
Severe hypernatremia: Overcorrection of hyponatremia can precipitate osmotic demyelination syndrome; serum sodium should be corrected no faster than 8-10 mmol/L within 24 hours.
Hypotension: Occasionally observed when combined with other diuretics or vasodilators.

Contraindications

Known hypersensitivity to tolvaptan or any excipients.
Inability to sense or respond to thirst, as the drug impairs normal fluid-intake cues.
Uncontrolled liver disease (e.g., cirrhosis with Child-Pugh class B or C).

Drug Interactions

CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin) raise tolvaptan plasma levels, increasing the risk of hepatotoxicity.
CYP3A4 inducers (e.g., rifampin, carbamazepine) reduce exposure, potentially diminishing efficacy.
Concomitant diuretics may amplify volume depletion; careful electrolyte monitoring is advised.
Other Vaptans (e.g., conivaptan) should not be used together due to overlapping mechanisms.

Special Populations

Pregnancy & Breastfeeding: Animal studies suggest fetal toxicity; the drug is contraindicated in pregnancy and nursing mothers.
Older Adults: Age-related decline in renal function may necessitate dose adjustment; close monitoring of electrolytes is recommended.
Renal Impairment: Not advised for patients with eGFR < 30 mL/min/1.73 m², as aquaresis may precipitate further kidney injury.
Hepatic Impairment: Baseline liver-function testing is mandatory; patients with moderate to severe hepatic disease should avoid the medication.

Frequently Asked Questions

How does Tolvaptan differ from other vasopressin antagonists? Unlike conivaptan, which blocks both V1A and V2 receptors and requires intravenous administration, tolvaptan is oral and selective for V2 receptors, providing a cleaner aquaresis profile with fewer vascular side effects.
How long before Tolvaptan produces noticeable effects for hyponatremia? Most patients see an increase of 3-5 mmol/L in serum sodium within the first 12 hours; a full correction to the target range generally occurs within 48-72 hours when dosing is optimized.
What should I do if I experience excessive thirst while taking Tolvaptan? Thirst is a common sign that the drug is working. Sip water regularly, but avoid large-volume fluid intake that could counteract the desired rise in serum sodium. If thirst becomes severe or is accompanied by dizziness, contact your clinician.
Can Tolvaptan be taken with food? Yes. Taking the tablet with a meal improves absorption and lessens gastrointestinal discomfort. Do not chew or crush the tablet, as this may affect release characteristics.
Is there a risk of liver damage with long-term Tolvaptan use? Liver-enzyme elevations occur in a minority of patients, especially during the first 18 months of therapy for ADPKD. Monthly monitoring for the first year, then every three months thereafter, is the standard safety protocol.
What medications should I avoid while on Tolvaptan? Strong CYP3A4 inhibitors (e.g., ketoconazole) and potent inducers (e.g., rifampin) can alter drug levels. Additionally, concurrent use of other diuretics may increase the chance of dehydration; your physician will adjust doses accordingly.
Does Tolvaptan affect blood pressure? The drug can cause modest reductions in blood pressure due to volume loss, particularly when combined with antihypertensives. Regular blood-pressure checks are advisable during the titration phase.
Can I stop Tolvaptan abruptly if I feel better? Sudden discontinuation may lead to rapid water retention and a rebound drop in serum sodium. Any change in therapy should be supervised by a healthcare professional who can schedule a gradual taper if needed.
What monitoring is required while taking Tolvaptan for ADPKD? Baseline liver-function tests, serum sodium, and renal labs are essential. Follow-up liver enzymes are checked monthly for the first 18 months, then quarterly. Imaging (MRI or ultrasound) may be performed annually to track kidney volume.
What information should I provide my doctor when discussing Tolvaptan?
- Full list of current prescription, over-the-counter, and herbal products.
- Recent laboratory results, especially liver enzymes, serum sodium, and kidney function.
- History of liver disease, dehydration, or difficulty sensing thirst.
- Specific treatment goals (e.g., correction of hyponatremia vs. slowing ADPKD progression).

Disclaimer

The information provided about Tolvaptan is for general knowledge only. It does not replace professional medical consultation or the official prescribing information for medications containing this ingredient. All treatment decisions, including dosing, formulation selection, and monitoring, should be made under the supervision of a qualified healthcare provider who can assess individual medical history, current medications, and specific health needs. We assume all readers are responsible adults capable of making informed decisions about their health. Our online pharmacy offers access to medications containing Tolvaptan for individuals who may have limited availability through traditional pharmacies, prescription-based insurance schemes, or who are seeking affordable generic alternatives. Always consult your doctor before starting, changing, or discontinuing any medication containing Tolvaptan.