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Dichlorphenamide 50 mg Tablet, 30-count — NDC 13668-0676-30 package photo

Dichlorphenamide 50 mg Tablet, 30-count

by Torrent pharmaceuticals limited · 30 TABLET in 1 BOTTLE (13668-676-30)
NDC 13668-0676-30
🏷️ FDA NDC (as labeled) 13668-676-30 billing pads the product segment with a zero
This package
Contains30-count Pack sizes2 compare ↓
Also priced by: Part D plans $192.22/unit — full pricing hub ↓
Also comes in: 100 tablets 13668-0676-01
Rx only Generic On market Non-controlled
🗂️ Data synced Jul 24, 2026 · sources: openFDA · FDA label (DailyMed) · FDA Orange & Purple Book · First Databank · CMS NADAC, ASP, Medicare & Medicaid · RxNorm
📋 All sources & update times →

This page is curated, coded, and maintained by

Compiled from public FDA, CMS, DailyMed, NADAC, and related drug data sources. Editorial policy

🆔 Identity & classification

FDA NDC (as labeled) 13668-676-30
Product NDC 13668-676
11-digit billing NDC 13668067630
RxCUI 197594
UNII VVJ6673MHY
UPC 0313668676303
Application # ANDA215924
SPL Set ID 64bf0c71-2113-47dc-8ce5-7fe535e558dc
Established class (EPC) Carbonic Anhydrase Inhibitor
Mechanism of action Carbonic Anhydrase Inhibitors
Chemical class Sulfonamides
DEA schedule Non-controlled
Marketing category ANDA
Marketing status On market
FDA listing status Listed (active directory)
Marketing start 2022-12-29
Route ORAL
Dosage form TABLET
Substance DICHLORPHENAMIDE
GPI-14 37100020000305
GCN Seq No 074933
GCN 39804
HICL code 003642
Ingredient (HICL) Dichlorphenamide
HIC1 code S
Therapeutic class — broad (HIC1) Locomotor System
HIC2 code S7
Therapeutic class — intermediate (HIC2) Affect Primarily Skeletal Muscle
HIC3 code S7F
Therapeutic class — specific (HIC3) Agents To Tx Periodic Paralysis - Carbon Anhyd Inh
AHFS code 92:26.00.00
AHFS class Carbonic Anhydrase Inhibitors (92:26)
FDB label name DICHLORPHENAMIDE 50 MG TABLET
FDB brand name Dichlorphenamide
Legend status F — Federal legend — prescription drug or device
TE code (Orange Book) AB · RLD · RS
Why two NDCs? The FDA registers this code as 13668-676-30 — a 5-3-2 layout, and that's what's printed on the package and shown on DailyMed. For insurance claims, every NDC is standardized to a uniform 11-digit 5-4-2 format by adding a zero to the product segment → 13668-0676-30. Same drug, same package — only the format differs.
Where does this data come from?
Identifiers from the FDA openFDA NDC Directory and Structured Product Labeling; RxCUI from RxNorm (NLM); GPI from Medi-Span; GCN / HIC / AHFS / legend from First Databank.

🏷️ RxNorm drug class

This medicine belongs to the Carbonic Anhydrase Inhibitor class.

Pharmacologic class Carbonic Anhydrase Inhibitor
Drug family (ATC) Carbonic anhydrase inhibitors
How it works Carbonic Anhydrase Inhibitors
Where does this data come from?
Therapeutic classes from RxNorm RxClass (U.S. National Library of Medicine) — Established Pharmacologic Class (FDA), ATC drug family (WHO) and mechanism of action, matched by this product’s RxCUI.

🏭 Manufacturer & labeler

LabelerTorrent pharmaceuticals limited
Application holderTORRENT PHARMA INC
FDA applicationANDA215924 (ANDA)
Labeler code13668
First marketedDec 2022
Product typeHuman Prescription Drug
Portfolio182 products on file
The labeler markets the product; the application holder owns the FDA approval. They’re often the same company but can differ (e.g. a repackager or an authorized generic). A mailing address / phone appears here when the manufacturer includes it in the product’s FDA label (not all do).
Where does this data come from?
Labeler, application holder and registered establishment from the FDA openFDA NDC Directory and Drugs@FDA; address/contact from the product’s FDA label.

🩺 Clinical

Label name DICHLORPHENAMIDE 50 MG TABLET Ingredient Dichlorphenamide
Where does this data come from?
Plain-language summary from MedlinePlus (U.S. National Library of Medicine); supplement & herbal interactions and nutrient depletion data from the Natural Medicines database; our full guide is HelloPharmacist editorial content.

💊 What it looks like

Color white
ShapeRound
ImprintZD;50
Size6 mm
ScoringScored — splits in 2
One label can cover several strengths, so colors may be combined — always confirm a loose pill against the dispensed prescription label or a pharmacist.
Where does this data come from?
Physical description (imprint, shape, color, scoring, coating) from this product’s FDA Structured Product Labeling (SPL), mirrored from DailyMed / openFDA.

🧪 Inactive Ingredients / Excipients

Inactive ingredients, also called excipients, are components of the drug product other than the active ingredient. They may include fillers, dyes, coatings, preservatives, flavors, or other formulation ingredients.

💡 Tap an ingredient (hover on desktop) to see what it is and why it’s used.

  • UNII EWQ57Q8I5X
    Lactose monohydrate is a natural sugar derived from milk. It serves as a filler and binder in tablets and capsules, helping create the proper size, texture, and consistency of the medicine.
  • UNII 70097M6I30
    Magnesium stearate is a salt made from magnesium and stearic acid, a fatty substance. It's used in tablets and capsules as a lubricant and glidant to help ingredients flow smoothly during manufacturing and prevent sticking.
  • UNII O8232NY3SJ
    A plant-based carbohydrate derived from corn kernels. It acts as a filler to add bulk, a binder to hold ingredients together, and a disintegrant to help the tablet break apart in your stomach for absorption.

3 inactive ingredients listed in the exact product block matched to this NDC.

Where does this data come from?
Data sourced from official FDA Structured Product Labeling (SPL) via DailyMed — ingredient classCode="IACT" elements from the exact product block matched by this NDC. Label-section narrative from DailyMed / the openFDA label index is shown separately when available.

Inactive ingredient FAQ

Are inactive ingredients the same for every manufacturer?
No. Inactive ingredients can differ by manufacturer, dosage form, strength, and package / product version.
Why might an inactive ingredient be missing?
Some SPLs do not provide a complete structured inactive-ingredient list, and older or unusual labels may only include the information in narrative text.
Can inactive ingredients matter?
Yes. They can matter for allergies, intolerances, dyes, gluten / lactose concerns, preservatives, and formulation differences — but confirm with a pharmacist or the manufacturer when it’s clinically important.

💲 Pricing

A drug doesn't have one price. Each row is a different public payment system, and none is what you'd pay at the counter — that depends on your insurance. The ⓘ on each row explains what it measures.

Price systemPer eachPer package
Retail pharmacies payNADAC · weekly Not in the retail survey — common for institutional, discontinued, or low-volume packs.
Medicaid paysCMS SDUD · 12 mo No recent Medicaid claims on file for this NDC — rare and low-volume NDCs are suppressed in the public data.
Medicare drug plans payPart D · Q2 2026 $192.22 $5,766.45 / 30 tablets
Where does this data come from?
NADAC (National Average Drug Acquisition Cost) is the CMS weekly pharmacy-acquisition-cost survey — what pharmacies pay. ASP (Average Sales Price) is the CMS Medicare Part B drug-payment file, published quarterly. Medicaid pays is computed by us from CMS State Drug Utilization Data (total reimbursed ÷ units, trailing 12 months) — gross of rebates and inclusive of dispensing fees, so it reflects what Medicaid paid, not an acquisition cost. Medicare drug plans pay is the median negotiated point-of-sale unit cost across plans listing this NDC in the CMS quarterly Prescription Drug Plan pricing files, before rebates. The VA pays is the federal contract price (FSS, and the statutory Big 4 ceiling where listed) from the VA National Acquisition Center pharmaceutical price file. All are free public government data; each measures a different payer, so the figures are not directly comparable.

🔁 Therapeutic equivalents

ProductLabelerPackNADAC/unitTEStatusPrice vs. this
Dichlorphenamide 50 mgthis 13668-0676-30 Torrent 30 tablets — AB FDA listed —
Dichlorphenamide 50 mg 16571-0242-01 Rising 100 tablets — AB FDA listed —
Ormalvi 50 mg 70709-0085-10 Cycle 100 tablets — AB FDA listed —
Keveyis 50 mg 72065-0001-01 Xeris 100 tablets — AB FDA listed —
About this product: this is a generic version of the medicine. FDA equivalence ratings are shown when available, and other versions are listed above, least expensive first.
Where does this data come from?
Equivalents are other NDCs of the same ingredient, form and route from the openFDA NDC Directory, ranked least-expensive-first by NADAC. Therapeutic-equivalence (AB) ratings come from the FDA Orange Book; biologics use the FDA Purple Book for biosimilar & interchangeable status.

⏳ Availability & generic status

🏛️
2022
On the market since
Dec 2022
📍
2026
Currently FDA-listed
4 years listed
🔓
·
Generic on the market
this product is a generic
✅This is a generic drug

This product is an FDA-approved generic. Other versions of the same drug are listed under Therapeutic equivalents, least expensive first.

Where does this data come from?
Patents and exclusivity from the FDA Orange Book (small-molecule drugs), refreshed from public FDA data. Generic launch timing is an estimate, not a guarantee.

📊 Medicare Part D spend CMS · PART D · 2026 (Q1)

Medicare Part D (outpatient prescription) spending for Dichlorphenamide — the program that covers self-administered drugs. 1 manufacturer.
⚠️ Drug-level data: CMS publishes Part D spending by drug, not by NDC — these figures combine every manufacturer, strength and package size sold under the name Dichlorphenamide. That’s a different level of aggregation than the Medicaid card above, which is specific to this exact 11-digit NDC (pack size included), so the two aren’t directly comparable.
Period
Total Part D spend
$375.9K
Claims incl. refills
29
Beneficiaries
12
Spend / beneficiary
$31,322.78
Spend / claim
$12,961.15
Trend by period
💵 About the dollar figures: spending is what Part D plans paid before confidential manufacturer rebates, so the program’s real net cost is lower. A blank patient count means fewer than 11 people — CMS hides counts that small to protect privacy. Source: CMS Medicare Quarterly Part D Spending by Drug (data.cms.gov), updated quarterly.

📦 Packaging — all sizes for this product

Package NDCDescription Marketing startStatus
13668-0676-01 100 TABLET in 1 BOTTLE (13668-676-01) 2022-12-29 Active
13668-0676-30 You're viewing this 30 TABLET in 1 BOTTLE (13668-676-30) 2022-12-29 Active

You're viewing the smallest of 2 pack sizes for this product.

Pack size FAQ

What quantity is in NDC 13668-0676-30?
NDC 13668-0676-30 is a 30-count package — 30 tablet in 1 bottle.
What is the difference between NDC 13668-0676-30 and NDC 13668-0676-01?
Both are Dichlorphenamide 50 mg Tablet — the drug itself is identical. NDC 13668-0676-30 is the 30-count package, while NDC 13668-0676-01 is the 100 tablets package.
What NDC number is used to bill for this package of Dichlorphenamide 50 mg Tablet?
Bill NDC 13668-0676-30 — the 11-digit billing format is 13668067630. Pharmacy and medical claims use the 11-digit form; the FDA label may print a shorter form of the same code.

🧭 About this NDC listing & data coverage

Finished prescription product
What data is (and isn’t) available for this NDC — tap to expand
NDC identity (package / product / labeler codes) ✓ Available
Labeler ✓ Available
Product & package description ✓ Available
Marketing category & status ✓ Available
Active ingredient / dosage form / route ✓ Available
FDA label (SPL via DailyMed) ✓ Available
Package photos ✓ Available
Inactive ingredients (structured) ✓ Available
NADAC pharmacy acquisition price (CMS) — Not published for this NDC CMS publishes NADAC only for NDCs reported in its retail-pharmacy survey.
Orange Book / therapeutic-equivalence data ✓ Available
HCPCS J-code billing crosswalk — Not published for this NDC Most self-administered / retail products have no J-code — that is normal.
Medicaid utilization (CMS SDUD) — Not published for this NDC CMS reports utilization only for NDCs with Medicaid claims above its privacy threshold.
“Not published” reflects what the public FDA / CMS / NLM sources provide for this exact package code — it is a property of the data feeds, not a judgment about the product.

Questions about this listing

Why is there no price listed?
The pricing shown on our NDC pages comes from CMS NADAC, a voluntary survey of retail community pharmacy invoices. CMS does not publish a NADAC for every NDC — packages outside the retail survey (institutional and hospital products, bulk packages, discontinued items, and many OTC items) may never receive one. A missing price reflects the survey's scope, not this product's actual cost, and does not mean the product is free or unavailable.
Is the NDC printed on the package the same as the 11-digit billing NDC?
Yes, they identify this exact package in different formats. The FDA registers it as 13668-676-30, which is what is printed on the packaging and shown on DailyMed. Insurance claims use a fixed 11-digit 5-4-2 format, so the short segment is padded with a leading zero: 13668-0676-30, written without dashes as 13668067630. The Identity section at the top of this page lists every form of this code.
What do the three segments of this NDC mean?
In 13668-0676-30, the first segment (13668) is the labeler code FDA assigned to Torrent pharmaceuticals limited; the middle segment (0676) identifies this specific product — its ingredient, strength, and dosage form; and the last segment (30) identifies this exact package size and type. Together they name one specific package of one specific product.
Is this package still being marketed?
Yes, per the latest FDA NDC Directory data on this page: this package is listed as actively marketed, with no marketing end date reported by Torrent pharmaceuticals limited. Listing status can change — the directory data on this page refreshes weekly.
Does this product come in other package sizes?
Yes — the FDA directory lists 1 other package presentation of this same product, including 100 tablets (13668-0676-01). Each has its own NDC and its own page — see the package list near the top of this page.
Who lists this product with the FDA?
Torrent pharmaceuticals limited is the labeler of record for this NDC — the company under whose FDA-assigned code the package is listed. The labeler may be the manufacturer itself or a distributor marketing the product under its own code.
Do I need a prescription for this product?
This NDC is listed with FDA as a prescription product, so it is dispensed under a prescriber's order. Your pharmacist can tell you whether any over-the-counter forms of the same medication exist.
This page identifies an FDA-listed package (the NDC) and reports public regulatory and pricing data about the listing. It is reference information, not a medical recommendation — talk to your pharmacist or prescriber about your own medication.
Where does this data come from?
Listing facts (marketing category, packager status, marketing dates) from the FDA openFDA NDC Directory; label availability from DailyMed; pricing coverage from CMS NADAC; equivalence scope from the FDA Orange Book.

📄 Full prescribing information FDA SPL

The complete FDA label for this product — the official prescribing information, verbatim, section by section. Jump with a chip, search within the label, or expand everything.
🎯 Indications and Usage ⏱️ Dosage and Administration 💊 Dosage Forms and Strengths ⛔ Contraindications ⚠️ Warnings and Cautions 🤒 Adverse Reactions 🔄 Drug Interactions 👥 Use in Specific Populations 🤰 Pregnancy 🧒 Pediatric Use 🧓 Geriatric Use 🆘 Overdosage 🧬 Clinical Pharmacology 🧬 Mechanism of Action 📦 How Supplied / Storage and Handling 📋 Description 💬 Information for Patients
🎯 Indications and Usage 50 words ▾

1 INDICATIONS AND USAGE Dichlorphenamide tablets are indicated for the treatment of primary hyperkalemic periodic paralysis, primary hypokalemic periodic paralysis, and related variants. Dichlorphenamide tablets are an oral carbonic anhydrase inhibitor indicated for the treatment of primary hyperkalemic periodic paralysis, primary hypokalemic periodic paralysis, and related variants ( 1 )

⏱️ Dosage and Administration 202 words ▾

2 DOSAGE AND ADMINISTRATION • Initate dosing at 50 mg by mouth once or twice daily ( 2.1 ) • Titrate up or down dose based on individual response ( 2.1 ) • The minimum recommended dosage is 50 mg daily, and the maximum recommended dosage is 200 mg daily ( 2.1 ) • Evaluate response to dichlorphenamide tablets after 2 months of treatment ( 2.2 )

2.1Dosage Information Initiate dosing at 50 mg by mouth or twice daily. The dosage may be increased or decreased based on individual response, at weekly intervalsn (or sooner in case of adverse reaction). The minimum recommended total daily dosage is 50 mg, and the maximum recommended total daily dosage is 200 mg.

2.2Monitoring to Assess Effectiveness Primary hyperkalemic periodic paralysis, primary hypokalemic periodic paralysis, and related variants are a heterogeneous group of conditions, for which the response to dichlorphenamide may vary. Therefore, prescribers should evaluate the patient's response to dichlorphenamide after 2 months of treatment to decide whether dichlorphenamide tablets should be continued.

2.3Monitoring to Assess Safety Baseline and periodic measurements of serum potassium and sodium bicarbonate during dichlorphenamide treatment is recommended [see Warnings and Precautions ( 5.3 , 5.4 )] .

💊 Dosage Forms and Strengths 41 words ▾

3 DOSAGE FORMS AND STRENGTHS White to off-white, round shaped, flat faced beveled edged tablet, scored on one side, engraved with ‘ZD’ above the score and ‘50’ below the score, the other side is plain. Tablets: 50 mg ( 3 )

⛔ Contraindications 97 words ▾

4 CONTRAINDICATIONS Dichlorphenamide is contraindicated in the following circumstances: Hypersensitivity to dichlorphenamide or other sulfonamides [see Warnings and Precautions ( 5.1 )] Concomitant use of dichlorphenamide and high dose aspirin [see Warnings and Precautions ( 5.2 ) and Drug Interactions ( 7.1 )] Severe pulmonary disease, limiting compensation to metabolic acidosis caused by dichlorphenamide [see Warnings and Precautions ( 5.4 )] Hepatic insufficiency: dichlorphenamide may aggravate hepatic encephalopathy.

Hepatic insufficiency ( 4 ) Severe pulmonary obstruction ( 4 ) Hypersensitivity to dichlorphenamide or other sulfonamides ( 4 ) Concomitant use with high dose aspirin ( 4 )

⚠️ Warnings and Cautions ~2 min read ▾

5 WARNINGS AND PRECAUTIONS Hypersensitivity and Other Life-Threatening Reactions: discontinue dichlorphenamide at the first appearance of skin rash or any sign of immune- mediated or idiosyncratic adverse reaction ( 5.1 ) Hypokalemia: baseline and periodic measurements of serum potassium are recommended; if hypokalemia develops or persists, consider reducing the dose or discontinuing dichlorphenamide and correcting potassium levels ( 5.3 ) Metabolic acidosis: baseline and periodic measurements of serum bicarbonate are recommended; if metabolic acidosis develops or persists, consider reducing the dose or discontinuing dichlorphenamide ( 5.4 ) Falls: consider reducing the dose or discontinuing dichlorphenamide in patients who experience falls ( 5.5 )

5.1Hypersensitivity and Other Life-Threatening Reactions Fatalities associated with the administration of sulfonamides have occurred because of adverse reactions including Stevens-Johnson syndrome, toxic epidermal necrolysis, fulminant hepatic necrosis, agranulocytosis, aplastic anemia, and other blood dyscrasias. Pulmonary involvement can occur in isolation or as part of a systemic reaction. Dichlorphenamide should be discontinued at the first appearance of skin rash or any sign of immune- mediated or other life-threatening adverse reaction.

5.2Concomitant Use of Aspirin or Other Salicylates Carbonic anhydrase inhibitors, including dichlorphenamide, can cause metabolic acidosis [see Warnings and Precautions ( 5.4 )] , which can increase the risk of salicylate toxicity. Anorexia, tachypnea, lethargy, and coma have been reported with concomitant use of dichlorphenamide and high-dose aspirin. Therefore, the concomitant use of dichlorphenamide and high-dose aspirin is contraindicated.

Patients with concomitant use of dichlorphenamide and low-dose aspirin should be carefully monitored.

5.3Hypokalemia Dichlorphenamide increases potassium excretion and can cause hypokalemia. The risk of hypokalemia is greater when dichlorphenamide is used in patients with conditions associated with hypokalemia (e.g., adrenocortical excess, renal tubular acidosis type 1 and 2), and in patients receiving other drugs that may cause hypokalemia [see Drug Interactions ( 7.3 ] . Baseline and periodic measurements of serum potassium during dichlorphenamide treatment is recommended.

If hypokalemia develops or persists, consideration should be given to reducing the dose or discontinuing dichlorphenamide and correction of potassium levels.

5.4Metabolic Acidosis Dichlorphenamide can cause hyperchloremic non-anion gap metabolic acidosis. Concomitant use of dichlorphenamide with other drugs that cause metabolic acidosis may increase the severity of acidosis. Concomitant use of dichlorphenamide in compensated patients with respiratory acidosis, such as in advanced lung diseases, may lead to respiratory decompensation.

Baseline and periodic measurements of serum bicarbonate during dichlorphenamide treatment are recommended. If metabolic acidosis develops or persists, consideration should be given to reducing the dose or discontinuing dichlorphenamide [see Drug Interactions ( 7.4) ].

5.5Falls Dichlorphenamide increases the risk of falls. The risk of falls is greater in the elderly and with higher doses of dichlorphenamide. Consider dose reduction or discontinuation of dichlorphenamide in patients who experience falls while treated with dichlorphenamide.

🤒 Adverse Reactions ~2 min read ▾

6 ADVERSE REACTIONS The following serious adverse reactions are described elsewhere in labeling: Hypersensitivity and Other Life-Threatening Reactions [see Warnings and Precautions ( 5.1 )] Hypokalemia [see Warnings and Precautions ( 5.3 )] Metabolic Acidosis [see Warnings and Precautions ( 5.4 )] Falls [ see Warnings and Precautions ( 5.5 )] Most common adverse reactions (incidence at least 10% and greater than placebo) include paresthesias, cognitive disorder, dysgeusia, and confusional state ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Torrent Pharma, Inc. at 1-800-912-9561 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

6.1Clinical Trial Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. In a 9-week randomized controlled trial in adults with hyperkalemic or hypokalemic periodic paralysis (Study 1), the most common adverse reactions in patients treated with dichlorphenamide, with rates greater than placebo, were paresthesia, cognitive disorder, dysgeusia, and confusional state.

The mean dose of dichlorphenamide was 94 mg/day in patients with hypokalemic periodic paralysis and 82 mg/day in patients with hyperkalemic periodic paralysis. Table 1 lists the incidence of adverse reactions that occurred in ≥5% of patients treated with dichlorphenamide and more commonly than in patients treated with placebo in Study 1. Table 1: Adverse Reactions in Patients Treated with dichlorphenamide with Incidence ≥ 5% and more common than in Patients Treated with Placebo in Study 1 Adverse Reaction Dichlorphenamide N = 36 (%) Placebo N = 29 (%) Paresthesia 44 14 Cognitive disorder 1 14 7 Dysgeusia 14 0 Nervous system disorders Confusional state 11 0 Headache 8 7 Hypoesthesia 8 0 Lethargy 8 0 Dizziness 6 0 Gastrointestinal disorders Diarrhea 6 3 Nausea 6 0 General disorders and administration site conditions Fatigue 8 0 Malaise 6 0 Investigations Weight decreased 6 0 Muscle spasms 8 0 Musculoskeletal and connective tissue disorders Arthralgia 6 3 Muscle twitching 6 0 Respiratory Dyspnea 6 0 Pharyngolaryngeal pain 6 0 Skin Rash 8 0 Pruritus 6 0 1 Cognitive disorder combined cases with the preferred terms of cognitive disorder, disturbance in attention, and mental impairment.

6.2Postmarketing Experience Adverse reactions have been identified during postapproval use of dichlorphenamide. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. The following are adverse reactions which have been reported during postapproval use of dichlorphenamide and were serious or are not reported in the previous section of labeling [see Clinical Trials Experience ( 6.1 ) ]: amnesia, cardiac failure, condition aggravated, convulsion, hallucination, nephrolithiasis, pancytopenia, psychotic disorder, renal tubular necrosis, stupor, syncope, tremor.

🔄 Drug Interactions ~1 min read ▾

7 DRUG INTERACTIONS Aspirin: anorexia, tachypnea, lethargy, and coma have been reported with concomitant use of dichlorphenamide and high-dose aspirin. The concomitant use of dichlorphenamide tablets and high-dose aspirin is contraindicated. Dichlorphenamide tablets should be used with caution in patients receiving lower doses of aspirin ( 4 , 5.2 , 7.1 )

7.1Aspirin and Other Salicylates Carbonic anhydrase inhibitors, including dichlorphenamide, can cause metabolic acidosis [see Warning and Precautions ( 5.2 , 5.4 )] , which can increase the risk of salicylate toxicity. Anorexia, tachypnea, lethargy, and coma have been reported with concomitant use of dichlorphenamide and high-dose aspirin. Therefore, concomitant use of dichlorphenamide and high-dose aspirin is contraindicated.

Patients with concomitant use of dichlorphenamide and low-dose aspirin should be carefully monitored [see Contraindications ( 4 ) and Warnings and Precautions ( 5.2 )].

7.2Drugs that are Substrates of Organic Anion Transporter1 (OAT1) In vitro , dichlorphenamide is an inhibitor of OAT1 transporters. The concomitant administration of dichlorphenamide may increase the plasma exposures of OAT1 substrates. Use of dichlorphenamide with drugs that are sensitive to OAT1 inhibition (e.g., methotrexate, famotidine, oseltamivir) is not recommended [see Clinical Pharmacology ( 12.3 )].

7.3Drugs that Cause Hypokalemia The risk of hypokalemia is greater with coadministration of dichlorphenamide and other drugs that can cause hypokalemia (e.g., loop diuretics, thiazide diuretics, laxatives, antifungals, penicillins, and theophylline) [see Warnings and Precautions ( 5.3 )].

7.4Drugs that Cause Metabolic Acidosis Coadministration of dichlorphenamide and other drugs that can cause metabolic acidosis may increase the severity of the acidosis [see Warnings and Precautions ( 5.4 )].

7.5Drugs that are Inhibitors of OAT1 or OAT3 An in vitro transporter study indicated that dichlorphenamide is a substrate of human transporters OAT1 and OAT3 [see Clinical Pharmacology ( 12.3 )] . Therefore, signs of dichlorphenamide toxicity should be monitored when administered with OAT1 or OAT3 inhibitors.

👥 Use in Specific Populations ~2 min read ▾

8 USE IN SPECIFIC POPULATIONS Pregnancy: Based on animal data, may cause fetal harm ( 8.1 )

8.1Pregnancy Risk Summary There are no adequate data on the developmental risk associated with the use of dichlorphenamide in pregnant women. A no-effect dose has not been established. Dichlorphenamide was teratogenic when administered orally to pregnant rats.

The background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4%, and 15% to 20%, respectively. Clinical Considerations Fetal/Neonatal adverse reactions Dichlorphenamide treatment can cause metabolic acidosis [see Warnings and Precautions ( 5.4 )] .

The effect of dichlorphenamide-induced metabolic acidosis has not been studied in pregnancy; however, metabolic acidosis in pregnancy (due to other causes) can cause decreased fetal growth, decreased fetal oxygenation, and fetal death, and may affect the fetus’ ability to tolerate labor. Pregnant patients should be monitored for metabolic acidosis and treated as in the nonpregnant state. Newborns of mothers treated with dichlorphenamide should be monitored for metabolic acidosis because of possible occurrence of transient metabolic acidosis following birth.

Labor or Delivery Although the effect of dichlorphenamide on labor and delivery in humans has not been established, the development of dichlorphenamide-induced metabolic acidosis in the mother and/or in the fetus might affect the fetus’ ability to tolerate labor. Data Animal Data Teratogenic effects (fetal limb reduction defects) were reported following oral administration of dichlorphenamide to pregnant rats during organogenesis at 350 mg/kg, or 17 times the maximum recommended human dose (200 mg/day) on a body surface area (mg/m 2 ) basis.

A no-effect dose for adverse effects on embryofetal development has not been established.

8.2Lactation Risk Summary There are no data on the presence of dichlorphenamide in human milk, the effects on the breastfed infant, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for dichlorphenamide and any potential adverse effects on the breastfed infant from dichlorphenamide or from the underlying maternal condition.

8.4Pediatric Use Safety and effectiveness of dichlorphenamide in pediatric patients have not been established.

8.5Geriatric Use The risk of falls and of metabolic acidosis are greater in elderly patients [see Warnings and Precautions ( 5.4 , 5.5 )].

🤰 Pregnancy ~1 min read ▾

8.1Pregnancy Risk Summary There are no adequate data on the developmental risk associated with the use of dichlorphenamide in pregnant women. A no-effect dose has not been established. Dichlorphenamide was teratogenic when administered orally to pregnant rats.

The background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4%, and 15% to 20%, respectively. Clinical Considerations Fetal/Neonatal adverse reactions Dichlorphenamide treatment can cause metabolic acidosis [see Warnings and Precautions ( 5.4 )] .

The effect of dichlorphenamide-induced metabolic acidosis has not been studied in pregnancy; however, metabolic acidosis in pregnancy (due to other causes) can cause decreased fetal growth, decreased fetal oxygenation, and fetal death, and may affect the fetus’ ability to tolerate labor. Pregnant patients should be monitored for metabolic acidosis and treated as in the nonpregnant state. Newborns of mothers treated with dichlorphenamide should be monitored for metabolic acidosis because of possible occurrence of transient metabolic acidosis following birth.

Labor or Delivery Although the effect of dichlorphenamide on labor and delivery in humans has not been established, the development of dichlorphenamide-induced metabolic acidosis in the mother and/or in the fetus might affect the fetus’ ability to tolerate labor. Data Animal Data Teratogenic effects (fetal limb reduction defects) were reported following oral administration of dichlorphenamide to pregnant rats during organogenesis at 350 mg/kg, or 17 times the maximum recommended human dose (200 mg/day) on a body surface area (mg/m 2 ) basis.

A no-effect dose for adverse effects on embryofetal development has not been established.

🧒 Pediatric Use 15 words ▾

8.4Pediatric Use Safety and effectiveness of dichlorphenamide in pediatric patients have not been established.

🧓 Geriatric Use 25 words ▾

8.5Geriatric Use The risk of falls and of metabolic acidosis are greater in elderly patients [see Warnings and Precautions ( 5.4 , 5.5 )].

🆘 Overdosage 45 words ▾

10 OVERDOSAGE Symptoms of overdosage or toxicity may include drowsiness, anorexia, nausea, vomiting, dizziness, ataxia, tremor, and tinnitus. In the event of overdosage, induce emesis or perform gastric lavage. The electrolyte disturbances most likely to be encountered from overdosage are hypokalemia and hyperchloremic metabolic acidosis.

🧬 Clinical Pharmacology ~2 min read ▾

12 CLINICAL PHARMACOLOGY

12.1Mechanism of Action Dichlorphenamide is a carbonic anhydrase inhibitor. However, the precise mechanism by which dichlorphenamide exerts its therapeutic effects in patients with primary periodic paralysis is unknown.

12.2Pharmacodynamics Dichlorphenamide can cause metabolic acidosis, which can increase the risk of salicylate toxicity with coadministration [see Warnings and Precautions ( 5.2 )] . Dichlorphenamide-induced metabolic acidosis can also increase in severity with coadministration of other drugs that cause metabolic acidosis [see Warnings and Precautions ( 5.4 )].

12.3Pharmacokinetics After single-dose administration in healthy subjects in fasted state, dichlorphenamide C max and AUC increased in a dose-proportional manner within the range of 25 mg to 400 mg (2 times the maximum recommended dose). The steady-state is expected to be achieved within 10 days of twice-daily dosing. Absorption The median time to reach maximum concentration (T max ) of dichlorphenamide was about 1.5 to 3 hours postdose after both single and multiple dose administrations.

Distribution The plasma protein binding of dichlorphenamide is approximately 88%. Elimination Following a single-dose administration, mean terminal half-life was in the range of 32 to 66 hours. Metabolism Dichlorphenamide is not a substrate for CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 isoforms when tested in vitro .

Drug Interaction Studies In vitro Assessment of Drug Interactions Drug-Metabolizing Enzyme Inhibition Dichlorphenamide is not an inhibitor for CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6, or 3A4 enzymes when tested in vitro. Drug-Metabolizing Enzyme Induction Dichlorphenamide is not an inducer for CYP1A2, 2B6, or 3A4 enzymes when tested in vitro . In vitro Assessment of Transporter-Drug Interactions Dichlorphenamide is neither a substrate nor inhibitor for p-gp, BCRP, OATP1B1, OATP1B3, OAT2, OAT4, OCT1, OCT2, MATE1, or MATE2-K when tested in vitro .

Dichlorphenamide is not an inhibitor of OAT3, but is an inhibitor of OAT1 based on in vitro studies [see Drug Interactions ( 7.4 )]. Dichlorphenamide is a substrate for transporters OAT1 and OAT3 based on in vitro studies [see Drug Interactions ( 7.2 )] In Vivo Drug Interactions The use of dichlorphenamide in combination with high-dose aspirin is contraindicated as it may lead to salicylate toxicity. The mechanism(s) of this interaction is not known.

Specific Populations Geriatrics The pharmacokinetics of dichlorphenamide in the elderly has not been determined.

🧬 Mechanism of Action 29 words ▾

12.1Mechanism of Action Dichlorphenamide is a carbonic anhydrase inhibitor. However, the precise mechanism by which dichlorphenamide exerts its therapeutic effects in patients with primary periodic paralysis is unknown.

📦 How Supplied / Storage and Handling 80 words ▾

16 HOW SUPPLIED/STORAGE AND HANDLING Each dichlorphenamide tablet USP, 50 mg is white to off-white, round shaped, flat faced beveled edged tablet, scored on one side, engraved with ‘ZD’ above the score and ‘50’ below the score, the other side is plain. Dichlorphenamide tablets are supplied as follows: Bottles of 30 NDC 13668-676-30 Bottles of 100 NDC 13668-676-01 Store at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F) [See USP Controlled Room Temperature].

📋 Description 115 words ▾

11 DESCRIPTION Dichlorphenamide tablets USP contain dichlorphenamide, an oral carbonic anhydrase inhibitor. Dichlorphenamide USP, a dichlorinated benzenedisulfonamide, is known chemically as 4, 5–dichloro- 1,3-benzenedisulfonamide. Its empirical formula is C 6 H 6 Cl 2 N 2 O 4 S 2 and its structural formula is: Dichlorphenamide USP is a white or practically white, crystalline powder with a molecular weight of 305.16.

It is very slightly soluble in water but soluble in dilute solutions of alkali carbonate and hydroxide. Dichlorphenamide tablets USP are supplied as tablets, for oral administration, each containing 50 mg dichlorphenamide USP. Inactive ingredients are lactose monohydrate, partially pregelatinized starch and magnesium stearate.

FDA Approved dissolution test specifications differ from USP. image description

💬 Information for Patients ~1 min read ▾

17 PATIENT COUNSELING INFORMATION Worsening of Symptoms Advise patients to notify their physician if they experience acute worsening of symptoms of periodic paralysis. Hypersensitivity and Other Life-threatening Reactions Inform patients that hypersensitivity and immune mediated reactions can occur with dichlorphenamide, and could be fatal. Advise patients to discontinue dichlorphenamide and notify their healthcare provider immediately if they develop a rash or signs and symptoms of anaphylaxis or other life-threatening reactions [see Warnings and Precautions ( 5.1 )].

Drug Interactions Instruct patients to notify their healthcare provider of all of the drugs and over-the-counter medications that they take and to not take aspirin or other salicylates without first discussing with their healthcare provider [see Drug Interactions ( 7.1 , 7.2 , 7.3 , 7.4 )]. Metabolic Acidosis Instruct patients to contact their healthcare provider immediately if they develop possible manifestations of metabolic acidosis (e.g., fast breathing, fatigue/tiredness, loss of appetite, or irregular heart beat or palpitations) [see Warnings and Precautions ( 5.4 )].

Falls Inform patients that dichlorphenamide can increase their risk of falls [see Warnings and Precautions ( 5.5 )]. Cognitive Impairment Advise patients to notify their healthcare provider if they experience symptoms of cognitive impairment including confusion and memory lapse [see Adverse Reactions ( 6.1 )]. Driving and Operating Machinery Dichlorphenamide may cause drowsiness/fatigue in some patients [see Adverse Reactions ( 6.1 )].

Caution patients on the potential for impaired ability to drive and operate machinery.

Source: FDA Structured Product Labeling, mirrored from DailyMed / openFDA. Prefer the government’s original formatting? View this label on DailyMed ↗
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For educational and professional reference only — not medical advice. Pricing reflects published NADAC and CMS ASP (free public data) and may differ from your acquisition cost; always verify before billing or dispensing.