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ACYCLOVIR 400 mg Tablet, 50-count — NDC 71335-1645-04 package photo

ACYCLOVIR 400 mg Tablet, 50-count

by Bryant Ranch Prepack · 50 TABLET in 1 BOTTLE (71335-1645-4)
NDC 71335-1645-04
🏷️ FDA NDC (as labeled) 71335-1645-4 billing pads the package segment with a zero
This package
Contains50-count Pack sizes10 compare ↓
Also priced by: Part D plans $0.1848/unit — full pricing hub ↓
Also comes in: 10 tablets 71335-1645-08 15 tablets 71335-1645-05 20 tablets 71335-1645-01 25 tablets 71335-1645-07 28 tablets 71335-1645-02 30 tablets 71335-1645-03 40 tablets 71335-1645-09 60 tablets 71335-1645-06 120 tablets 71335-1645-00
Rx only Generic On market Non-controlled
🗂️ Data synced Sep 10, 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) 71335-1645-4
Product NDC 71335-1645
11-digit billing NDC 71335164504
RxCUI 197311
UNII X4HES1O11F
Application # ANDA074891
SPL Set ID 331fe0bd-6bb2-4337-8faa-d0c82ff54dc7
Established class (EPC) Herpes Simplex Virus Nucleoside Analog DNA Polymerase Inhibitor; Herpes Zoster Virus Nucleoside Analog DNA Polymerase Inhibitor; Herpesvirus Nucleoside Analog DNA Polymerase Inhibitor
Mechanism of action DNA Polymerase Inhibitors
DEA schedule Non-controlled
Marketing category ANDA
Marketing status On market
FDA listing status Listed (active directory)
Marketing start 2013-08-08
Route ORAL
Dosage form TABLET
Substance ACYCLOVIR
TE code (Orange Book) AB · RLD · RS
Why two NDCs? The FDA registers this code as 71335-1645-4 — a 5-4-1 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 package segment → 71335-1645-04. 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 Herpesvirus Nucleoside Analog DNA Polymerase Inhibitor class.

Pharmacologic class Herpesvirus Nucleoside Analog DNA Polymerase Inhibitor, Herpes Simplex Virus Nucleoside Analog DNA Polymerase Inhibitor, Herpes Zoster Virus Nucleoside Analog DNA Polymerase Inhibitor
Drug family (ATC) Antivirals, Nucleosides and nucleotides excl. reverse transcriptase inhibitors, Antivirals
How it works DNA Polymerase 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

LabelerBryant Ranch Prepack
Application holderHERITAGE PHARMACEUTICALS INC DBA AVET PHARMACEUTICALS INC
FDA applicationANDA074891 (ANDA)
Labeler code71335
First marketedAug 2013
Product typeHuman Prescription Drug
Portfolio4,433 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

📗 Our plain-language guide HelloPharmacist
  • Acyclovir doesn't cure herpes — it can't eliminate the virus from your body. What it does is slow down the virus's ability to copy itself, which shortens outbreaks, eases symptoms,...
  • What exactly does acyclovir do — does it cure herpes?
  • Timing really does matter with acyclovir. For cold sores, you want to start at the very first warning sign — that tingling or itching feeling — before a sore even appears. For geni...
  • How soon do I need to start taking it for it to work?
📖 Read our full Acyclovir guide →
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
ImprintHP;227
Size12 mm
ScoringNot scored
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 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 OP1R32D61U
    Microcrystalline cellulose is a purified form of cellulose, a natural fiber from plant sources. It acts as a binder and filler in tablets and capsules, helping hold ingredients together and give the medicine its shape and size.
  • UNII K0KQV10C35
    Povidone K25 is a synthetic polymer made from vinyl pyrrolidone. It acts as a binder to hold tablet ingredients together and as a disintegrant to help the tablet break apart in the stomach for better absorption.
  • UNII ETJ7Z6XBU4
    Silicon dioxide is a naturally occurring mineral used as a glidant and anti-caking agent. It helps powder ingredients flow smoothly and prevents clumping during manufacturing and storage.
  • UNII 5856J3G2A2
    A starch-based powder made from potatoes and processed with sodium. It acts as a disintegrant, helping the tablet or capsule break apart quickly in the stomach so the medicine can be absorbed.

5 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 $0.1848 $9.24 / 50 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
Acyclovir 400 mg 00904-7507-61 Major 100 tablets $0.099 AB Availability likely —
Acyclovir 400 mg 23155-0227-01 Heritage 100 tablets $0.099 AB Availability likely —
Acyclovir 400 mg 31722-0777-01 Camber 100 tablets $0.099 AB Availability likely —
Acyclovir 400 mg 50268-0061-15 AvPAK 50 tablets $0.099 AB Availability likely —
Acyclovir 400 mg 59651-0965-01 Aurobindo 100 tablets $0.099 AB Availability likely —
acyclovir 400 mg 60505-5306-01 Apotex 100 tablets $0.099 AB Availability likely —
Acyclovir 400 mg 60687-0856-01 American 100 tablets $0.099 AB Availability likely —
Acyclovir 400 mg 61442-0112-01 Carlsbad 100 tablets $0.099 AB Availability likely —
acyclovir 400 mg 68382-0791-01 Zydus 100 tablets $0.099 AB Availability likely —
Acyclovir 400 mg 69367-0137-01 Westminster 100 tablets $0.099 AB Availability likely —
Acyclovir 400 mg 69452-0290-20 Bionpharma 100 tablets $0.099 AB Availability likely —
Acyclovir 400 mg 69117-0018-01 YILING 100 tablets $0.109 AB FDA listed —
Acyclovir 400 mg 43063-0928-04 PD-Rx 4 tablets — AB FDA listed —
acyclovir 400 mg 50090-3250-00 A-S 2 tablets — AB FDA listed —
acyclovir 400 mg 50090-3254-00 A-S 90 tablets — AB FDA listed —
Acyclovir 400 mg 50090-6844-00 A-S 90 tablets — AB FDA listed —
Acyclovir 400 mg 50090-7275-02 A-S 25 tablets — AB FDA listed —
Acyclovir 400 mg 50090-7276-00 A-S 90 tablets — AB FDA listed —
Acyclovir 400 mg 50090-7277-00 A-S 90 tablets — AB FDA listed —
Acyclovir 400 mg 51407-0145-01 Golden 100 tablets — AB FDA listed —
Acyclovir 400 mg 51655-0300-23 Northwind 25 tablets — AB FDA listed —
Acyclovir 400 mg 54348-0627-10 PharmPak, 10 tablets — AB FDA listed —
Acyclovir 400 mg 55154-4332-00 Cardinal 10 tablets — AB FDA listed —
Acyclovir 400 mg 63187-0253-15 Proficient 15 tablets — AB FDA listed —
acyclovir 400 mg 65841-0802-01 Zydus 100 tablets — AB FDA listed —
acyclovir 400 mg 67296-1707-02 RedPharm 20 tablets — AB Discontinued —
Acyclovir 400 mg 67296-2162-02 Redpharm 20 tablets — AB FDA listed —
Acyclovir 400 mg 68071-1841-01 NuCare 100 tablets — AB FDA listed —
acyclovir 400 mg 68071-2247-01 NuCare 100 tablets — AB FDA listed —
Acyclovir 400 mg 68071-2279-08 NuCare 15 tablets — AB FDA listed —
acyclovir 400 mg 68071-2287-04 NuCare 4 tablets — AB FDA listed —
Acyclovir 400 mg 68071-2447-01 NuCare 21 tablets — AB FDA listed —
Acyclovir 400 mg 68071-2811-05 NuCare 25 tablets — AB FDA listed —
Acyclovir 400 mg 68071-3573-04 NuCare 4 tablets — AB FDA listed —
Acyclovir 400 mg 68071-4799-05 NuCare 25 tablets — AB FDA listed —
Acyclovir 400 mg 68788-8203-01 Preferred 100 tablets — AB FDA listed —
Acyclovir 400 mg 68788-8724-01 Preferred 100 tablets — AB FDA listed —
acyclovir 400 mg 70518-0427-01 REMEDYREPACK 30 tablets — AB Discontinued —
acyclovir 400 mg 70518-1363-00 REMEDYREPACK 15 tablets — AB FDA listed —
Acyclovir 400 mg 70518-2117-00 REMEDYREPACK 30 tablets — AB FDA listed —
Acyclovir 400 mg 70518-2455-01 REMEDYREPACK 15 tablets — AB Discontinued —
Acyclovir 400 mg 70518-4414-00 REMEDYREPACK 30 tablets — AB FDA listed —
Acyclovir 400 mg 71205-0056-30 Proficient 30 tablets — AB FDA listed —
Acyclovir 400 mg 71205-0371-30 Proficient 30 tablets — AB FDA listed —
acyclovir 400 mg 71205-0391-25 Proficient 25 tablets — AB FDA listed —
Acyclovir 400 mg 71205-0472-15 Proficient 15 tablets — AB FDA listed —
Acyclovir 400 mg 71209-0005-05 Cadila 100 tablets — AB FDA listed —
Acyclovir 400 mg 71335-0323-00 Bryant 120 tablets — AB FDA listed —
Acyclovir 400 mg 71335-1053-00 Bryant 120 tablets — AB FDA listed —
Acyclovir 400 mgthis 71335-1645-04 Bryant 50 tablets — AB FDA listed —
Acyclovir 400 mg 71335-1757-01 Bryant 35 tablets — AB FDA listed —
Acyclovir 400 mg 71335-2229-01 Bryant 35 tablets — AB FDA listed —
Acyclovir 400 mg 71335-2619-01 Bryant 35 tablets — AB FDA listed —
Acyclovir 400 mg 71335-3103-00 Bryant 120 tablets — AB FDA listed —
Acyclovir 400 mg 71335-9620-00 Bryant 120 tablets — AB FDA listed —
Acyclovir 400 mg 72162-1735-01 Bryant 120 tablets — AB FDA listed —
Acyclovir 400 mg 72189-0631-14 Direct_Rx 14 tablets — AB FDA listed —
Acyclovir 400 mg 72241-0026-05 Modavar 100 tablets — AB FDA listed —
Acyclovir 400 mg 75834-0122-01 Nivagen 100 tablets — AB Discontinued —
acyclovir 400 mg 76420-0050-15 Asclemed 15 tablets — AB FDA listed —
Acyclovir 400 mg 76483-0047-00 SQUARE 30 tablets — AB FDA listed —
Acyclovir 400 mg 80425-0270-01 Advanced 40 tablets — AB FDA listed —
Acyclovir 400 mg 82804-0005-06 Proficient 6 tablets — AB FDA listed —
Acyclovir 400 mg 72789-0587-30 PD-Rx 30 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

🏛️
2013
On the market since
Aug 2013
📍
2026
Currently FDA-listed
13 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 Acyclovir — the program that covers self-administered drugs. 29 manufacturers.
⚠️ 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 Acyclovir. 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
$11.1M
Claims incl. refills
517.4K
Beneficiaries
366.8K
Spend / beneficiary
$30.28
Spend / claim
$21.46
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.

🔬 Reported adverse events (FAERS)

Read carefully: FAERS reports are voluntary and unverified. Counts are not incidence, do not establish causation, are subject to reporting bias, and cannot be used to compare one drug to another. Shown for signal context only. Reports for Acyclovir — the ingredient across all brands.

Top reported reactions

Fatigue8,029
Diarrhoea7,348
Pneumonia5,700
Nausea5,643
Pyrexia4,989
Death4,896
Rash4,296

Age at onset

Neonate121
Infant157
Child436
Adolescent193
Adult8,482
Elderly12,300

Reporter sex

114,761 reports
Male · 50%
Female · 50%
Unknown · 0%

Serious outcomes

Hospitalization42,634
Life-threatening6,235
Disabling1,985
Reports over time (by year) — tap or hover for the count & year
2024 2025 2026 8,378 3,543
Most recent year is provisional (FAERS lags ~3 months).
Where does this data come from?
Adverse-event reports from the FDA Adverse Event Reporting System (FAERS) via openFDA. FAERS reports are voluntary and unverified — counts are not incidence and don’t establish causation.

📦 Packaging — all sizes for this product

Package NDCDescription Marketing startStatus
71335-1645-00 120 TABLET in 1 BOTTLE (71335-1645-0) 2020-07-09 Active
71335-1645-01 20 TABLET in 1 BOTTLE (71335-1645-1) 2020-07-02 Active
71335-1645-02 28 TABLET in 1 BOTTLE (71335-1645-2) 2022-01-28 Active
71335-1645-03 30 TABLET in 1 BOTTLE (71335-1645-3) 2020-06-25 Active
71335-1645-04 You're viewing this 50 TABLET in 1 BOTTLE (71335-1645-4) 2022-01-28 Active
71335-1645-05 15 TABLET in 1 BOTTLE (71335-1645-5) 2022-01-28 Active
71335-1645-06 60 TABLET in 1 BOTTLE (71335-1645-6) 2020-09-23 Active
71335-1645-07 25 TABLET in 1 BOTTLE (71335-1645-7) 2020-12-18 Active
71335-1645-08 10 TABLET in 1 BOTTLE (71335-1645-8) 2020-12-23 Active
71335-1645-09 40 TABLET in 1 BOTTLE (71335-1645-9) 2022-01-28 Active

You're viewing one of 10 pack sizes for this product.

Pack size FAQ

What quantity is in NDC 71335-1645-04?
NDC 71335-1645-04 is a 50-count package — 50 tablet in 1 bottle.
What is the difference between NDC 71335-1645-04 and NDC 71335-1645-08?
Both are ACYCLOVIR 400 mg Tablet — the drug itself is identical. NDC 71335-1645-04 is the 50-count package, while NDC 71335-1645-08 is the 10 tablets package.
What NDC number is used to bill for this package of ACYCLOVIR 400 mg Tablet?
Bill NDC 71335-1645-04 — the 11-digit billing format is 71335164504. 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 71335-1645-4, 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: 71335-1645-04, written without dashes as 71335164504. 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 71335-1645-04, the first segment (71335) is the labeler code FDA assigned to Bryant Ranch Prepack; the middle segment (1645) identifies this specific product — its ingredient, strength, and dosage form; and the last segment (04) 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 Bryant Ranch Prepack. 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 9 other package presentations of this same product, including 10 tablets (71335-1645-08), 15 tablets (71335-1645-05), 20 tablets (71335-1645-01). 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?
Bryant Ranch Prepack 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 ⛔ Contraindications ⚠️ Warnings 🤒 Adverse Reactions 🆘 Overdosage 🧬 Clinical Pharmacology 📦 How Supplied / Storage and Handling 📋 Description
🎯 Indications and Usage 53 words ▾

INDICATIONS AND USAGE Herpes Zoster Infections: Acyclovir tablets, USP are indicated for the acute treatment of herpes zoster (shingles). Genital Herpes: Acyclovir tablets, USP are indicated for the treatment of initial episodes and the management of recurrent episodes of genital herpes. Chickenpox: Acyclovir tablets, USP are indicated for the treatment of chickenpox (varicella).

⏱️ Dosage and Administration ~2 min read ▾

DOSAGE AND ADMINISTRATION Acute Treatment of Herpes Zoster: 800 mg every 4 hours orally, 5 times daily for 7 to 10 days. Genital Herpes: Treatment of Initial Genital Herpes : 200 mg every 4 hours, 5 times daily for 10 days. Chronic Suppressive Therapy for Recurrent Disease: 400 mg 2 times daily for up to 12 months, followed by re-evaluation.

Alternative regimens have included doses ranging from 200 mg 3 times daily to 200 mg 5 times daily. The frequency and severity of episodes of untreated genital herpes may change over time. After 1 year of therapy, the frequency and severity of the patient's genital herpes infection should be re-evaluated to assess the need for continuation of therapy with acyclovir.

Intermittent Therapy : 200 mg every 4 hours, 5 times daily for 5 days. Therapy should be initiated at the earliest sign or symptom (prodrome) of recurrence. Treatment of Chickenpox: Children (2 years of age and older): 20 mg/kg per dose orally 4 times daily (80 mg/kg/day) for 5 days.

Children over 40 kg should receive the adult dose for chickenpox. Adults and Children over 40 kg: 800 mg 4 times daily for 5 days. Intravenous acyclovir is indicated for the treatment of varicella-zoster infections in immunocompromised patients.

When therapy is indicated, it should be initiated at the earliest sign or symptom of chickenpox. There is no information about the efficacy of therapy initiated more than 24 hours after onset of signs and symptoms. Patients With Acute or Chronic Renal Impairment: In patients with renal impairment, the dose of acyclovir tablets should be modified as shown in Table 3.

Table 3. Dosage Modification for Renal Impairment Normal Dosage Regimen Creatinine Clearance (mL/min/1.73 m 2 ) Adjusted Dosage Regimen Dose (mg) Dosing Interval 200 mg every 4 hours >10 0-10 200 200 every 4 hours, 5x daily every 12 hours 400 mg every 12 hours >10 0-10 400 200 every 12 hours every 12 hours 800 mg every 4 hours >25 10-25 0-10 800 800 800 every 4 hours, 5x daily every 8 hours every 12 hours Hemodialysis: For patients who require hemodialysis, the mean plasma half-life of acyclovir during hemodialysis is approximately 5 hours.

This results in a 60% decrease in plasma concentrations following a 6-hour dialysis period. Therefore, the patient's dosing schedule should be adjusted so that an additional dose is administered after each dialysis. Peritoneal Dialysis: No supplemental dose appears to be necessary after adjustment of the dosing interval.

Bioequivalence of Dosage Forms: Acyclovir suspension was shown to be bioequivalent to acyclovir capsules (n = 20) and one acyclovir 800-mg tablet was shown to be bioequivalent to four acyclovir 200-mg capsules (n = 24).

⛔ Contraindications 13 words ▾

CONTRAINDICATIONS Acyclovir is contraindicated for patients who develop hypersensitivity to acyclovir or valacyclovir.

⚠️ Warnings 52 words ▾

WARNINGS Acyclovir tablets are intended for oral ingestion only. Renal failure, in some cases resulting in death, has been observed with acyclovir therapy (see ADVERSE REACTIONS: Observed During Clinical Practice and OVERDOSAGE ). Thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS), which has resulted in death, has occurred in immunocompromised patients receiving acyclovir therapy.

🤒 Adverse Reactions ~2 min read ▾

ADVERSE REACTIONS Herpes Simplex: Short-Term Administration: The most frequent adverse events reported during clinical trials of treatment of genital herpes with acyclovir 200 mg administered orally 5 times daily every 4 hours for 10 days were nausea and/or vomiting in 8 of 298 patient treatments (2.7%). Nausea and/or vomiting occurred in 2 of 287 (0.7%) patients who received placebo. Long-Term Administration: The most frequent adverse events reported in a clinical trial for the prevention of recurrences with continuous administration of 400 mg (two 200-mg capsules) 2 times daily for 1 year in 586 patients treated with acyclovir were nausea (4.8%) and diarrhea (2.4%).

The 589 control patients receiving intermittent treatment of recurrences with acyclovir for 1 year reported diarrhea (2.7%), nausea (2.4%), and headache (2.2%). Herpes Zoster: The most frequent adverse event reported during 3 clinical trials of treatment of herpes zoster (shingles) with 800 mg of oral acyclovir 5 times daily for 7 to 10 days in 323 patients was malaise (11.5%). The 323 placebo recipients reported malaise (11.1%).

Chickenpox: The most frequent adverse event reported during 3 clinical trials of treatment of chickenpox with oral acyclovir at doses of 10 to 20 mg/kg 4 times daily for 5 to 7 days or 800 mg 4 times daily for 5 days in 495 patients was diarrhea (3.2%). The 498 patients receiving placebo reported diarrhea (2.2%). Observed During Clinical Practice: In addition to adverse events reported from clinical trials, the following events have been identified during post-approval use of acyclovir.

Because they are reported voluntarily from a population of unknown size, estimates of frequency cannot be made. These events have been chosen for inclusion due to either their seriousness, frequency of reporting, potential causal connection to acyclovir, or a combination of these factors. General: Anaphylaxis, angioedema, fever, headache, pain, peripheral edema.

Nervous: Aggressive behavior, agitation, ataxia, coma, confusion, decreased consciousness, delirium, dizziness, dysarthria, encephalopathy, hallucinations, paresthesia, psychosis, seizure, somnolence, tremors. These symptoms may be marked, particularly in older adults or in patients with renal impairment (see PRECAUTIONS ). Digestive: Diarrhea, gastrointestinal distress, nausea.

Hematologic and Lymphatic: Anemia, leukocytoclastic vasculitis, leukopenia, lymphadenopathy, thrombocytopenia. Hepatobiliary Tract and Pancreas: Elevated liver function tests, hepatitis, hyperbilirubinemia, jaundice. Musculoskeletal: Myalgia.

Skin: Alopecia, erythema multiforme, photosensitive rash, pruritus, rash, Stevens-Johnson syndrome, toxic epidermal necrolysis, urticaria. Special Senses: Visual abnormalities. Urogenital: Renal failure, renal pain (may be associated with renal failure), elevated blood urea nitrogen, elevated creatinine, hematuria (see WARNINGS ).

🆘 Overdosage 110 words ▾

OVERDOSAGE Overdoses involving ingestion of up to 100 capsules (20 g) have been reported. Adverse events that have been reported in association with overdosage include agitation, coma, seizures, and lethargy. Precipitation of acyclovir in renal tubules may occur when the solubility (2.5 mg/mL) is exceeded in the intratubular fluid.

Overdosage has been reported following bolus injections or inappropriately high doses and in patients whose fluid and electrolyte balance were not properly monitored. This has resulted in elevated BUN and serum creatinine and subsequent renal failure. In the event of acute renal failure and anuria, the patient may benefit from hemodialysis until renal function is restored (see DOSAGE AND ADMINISTRATION ).

🧬 Clinical Pharmacology ~3 min read ▾

CLINICAL PHARMACOLOGY Pharmacokinetics: The pharmacokinetics of acyclovir after oral administration have been evaluated in healthy volunteers and in immunocompromised patients with herpes simplex or varicella-zoster virus infection. Acyclovir pharmacokinetic parameters are summarized in Table 1. Table 1.

Acyclovir Pharmacokinetic Characteristics (Range) *Bioavailability decreases with increasing dose. Parameter Range Plasma protein binding 9% to 33% Plasma elimination half-life 2.5 to 3.3 hr Average oral bioavailability 10% to 20%* In one multiple-dose, crossover study in healthy subjects (n = 23), it was shown that increases in plasma acyclovir concentrations were less than dose proportional with increasing dose, as shown in Table 2. The decrease in bioavailability is a function of the dose and not the dosage form.

Table 2. Acyclovir Peak and Trough Concentrations at Steady State Parameter 200 mg 400 mg 800 mg 0.83 mcg/mL 1.21 mcg/mL 1.61 mcg/mL 0.46 mcg/mL 0.63 mcg/mL 0.83 mcg/mL There was no effect of food on the absorption of acyclovir (n = 6); therefore, acyclovir tablets may be administered with or without food. The only known urinary metabolite is 9-[(carboxymethoxy)methyl]guanine.

Special Populations: Adults With Impaired Renal Function: The half-life and total body clearance of acyclovir are dependent on renal function. A dosage adjustment is recommended for patients with reduced renal function (see DOSAGE AND ADMINISTRATION ). Geriatrics: Acyclovir plasma concentrations are higher in geriatric patients compared with younger adults, in part due to age-related changes in renal function.

Dosage reduction may be required in geriatric patients with underlying renal impairment (see PRECAUTIONS: Geriatric Use ). Pediatrics: In general, the pharmacokinetics of acyclovir in pediatric patients is similar to that of adults. Mean half-life after oral doses of 300 mg/m 2 and 600 mg/m 2 in pediatric patients aged 7 months to 7 years was 2.6 hours (range 1.59 to 3.74 hours).

Drug Interactions: Coadministration of probenecid with intravenous acyclovir has been shown to increase the mean acyclovir half-life and the area under the concentration-time curve. Urinary excretion and renal clearance were correspondingly reduced. Clinical Trials: Initial Genital Herpes: Double-blind, placebo-controlled studies have demonstrated that orally administered acyclovir significantly reduced the duration of acute infection and duration of lesion healing.

The duration of pain and new lesion formation was decreased in some patient groups. Recurrent Genital Herpes: Double-blind, placebo-controlled studies in patients with frequent recurrences (6 or more episodes per year) have shown that orally administered acyclovir given daily for 4 months to 10 years prevented or reduced the frequency and/or severity of recurrences in greater than 95% of patients. In a study of patients who received acyclovir 400 mg twice daily for 3 years, 45%, 52%, and 63% of patients remained free of recurrences in the first, second, and third years, respectively.

Serial analyses of the 3-month recurrence rates for the patients showed that 71% to 87% were recurrence free in each quarter. Herpes Zoster Infections: In a double-blind, placebo-controlled study of immunocompetent patients with localized cutaneous zoster infection, acyclovir (800 mg 5 times daily for 10 days) shortened the times to lesion scabbing, healing, and complete cessation of pain, and reduced the duration of viral shedding and the duration of new lesion formation. In a similar double-blind, placebo-controlled study, acyclovir (800 mg 5 times daily for 7 days) shortened the times to complete lesion scabbing, healing, and cessation of pain; reduced the duration of new lesion formation; and reduced the prevalence of localized zoster-associated neurologic symptoms (paresthesia, dysesthesia, or hyperesthesia).

Treatment was begun within 72 hours of rash onset and was most effective if started within the first 48 hou…

📦 How Supplied / Storage and Handling 129 words ▾

HOW SUPPLIED Acyclovir Tablets, USP are available as: 400 mg: Each round tablet is white to off-white and debossed with HP 227 on one side and plain on the other side. NDC: 71335-1645-1: 20 Tablets in a BOTTLE NDC: 71335-1645-2: 28 Tablets in a BOTTLE NDC: 71335-1645-3: 30 Tablets in a BOTTLE NDC: 71335-1645-4: 50 Tablets in a BOTTLE NDC: 71335-1645-5: 15 Tablets in a BOTTLE NDC: 71335-1645-6: 60 Tablets in a BOTTLE NDC: 71335-1645-7: 25 Tablets in a BOTTLE NDC: 71335-1645-8: 10 Tablets in a BOTTLE NDC: 71335-1645-9: 40 Tablets in a BOTTLE NDC: 71335-1645-0: 120 Tablets in a BOTTLE Store at 20° to 25°C (68° to 77°F) [See USP Controlled Room Temperature] and protect from light and moisture.

Repackaged/Relabeled by: Bryant Ranch Prepack, Inc. Burbank, CA 91504

📋 Description ~2 min read ▾

DESCRIPTION Acyclovir tablets, USP is a formulation for oral administration. Each tablet for oral administration contains 400 mg or 800 mg of acyclovir, USP. In addition each tablet contains the following inactive ingredients, magnesium stearate, microcrystalline cellulose, povidone, silicon dioxide and sodium starch glycolate.

Acyclovir is a white, crystalline powder with the molecular formula C 8 H 11 N 5 O 3 and a molecular weight of 225. The maximum solubility in water at 37°C is 2.5 mg/mL. The pka's of acyclovir are 2.27 and 9.25.

The chemical name of acyclovir is 2-amino-1,9-dihydro-9-[(2-hydroxyethoxy)methyl]-6H-purin-6-one; it has the following structural formula: VIROLOGY Mechanism of Antiviral Action: Acyclovir is a synthetic purine nucleoside analogue with in vitro and in vivo inhibitory activity against herpes simplex virus types 1 (HSV-1), 2 (HSV-2), and varicella-zoster virus (VZV). The inhibitory activity of acyclovir is highly selective due to its affinity for the enzyme thymidine kinase (TK) encoded by HSV and VZV. This viral enzyme converts acyclovir into acyclovir monophosphate, a nucleotide analogue.

The monophosphate is further converted into diphosphate by cellular guanylate kinase and into triphosphate by a number of cellular enzymes. In vitro , acyclovir triphosphate stops replication of herpes viral DNA. This is accomplished in 3 ways: 1) competitive inhibition of viral DNA polymerase, 2) incorporation into and termination of the growing viral DNA chain, and 3) inactivation of the viral DNA polymerase.

The greater antiviral activity of acyclovir against HSV compared with VZV is due to its more efficient phosphorylation by the viral TK. Antiviral Activities: The quantitative relationship between the in vitro susceptibility of herpes viruses to antivirals and the clinical response to therapy has not been established in humans, and virus sensitivity testing has not been standardized. Sensitivity testing results, expressed as the concentration of drug required to inhibit by 50% the growth of virus in cell culture (IC 50 ), vary greatly depending upon a number of factors.

Using plaque-reduction assays, the IC 50 against herpes simplex virus isolates ranges from 0.02 to 13.5 mcg/mL for HSV-1 and from 0.01 to 9.9 mcg/mL for HSV-2. The IC 50 for acyclovir against most laboratory strains and clinical isolates of VZV ranges from 0.12 to 10.8 mcg/mL. Acyclovir also demonstrates activity against the Oka vaccine strain of VZV with a mean IC 50 of 1.35 mcg/mL.

Drug Resistance: Resistance of HSV and VZV to acyclovir can result from qualitative and quantitative changes in the viral TK and/or DNA polymerase. Clinical isolates of HSV and VZV with reduced susceptibility to acyclovir have been recovered from immunocompromised patients, especially with advanced HIV infection. While most of the acyclovir-resistant mutants isolated thus far from immunocompromised patients have been found to be TK-deficient mutants, other mutants involving the viral TK gene (TK partial and TK altered) and DNA polymerase have been isolated.

TK-negative mutants may cause severe disease in infants and immunocompromised adults. The possibility of viral resistance to acyclovir should be considered in patients who show poor clinical response during therapy.

Source: FDA Structured Product Labeling, mirrored from DailyMed / openFDA. Prefer the government’s original formatting? View this label on DailyMed ↗
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