Duralyn CR

By Medically reviewed by hellodoktor

Generic Name: Duralyn CR Brand Name(s): Generics only. No brands available.


What is duralyn CR (theophylline) used for?

Duralyn CR is commonly used for symptomatic relief or prevention of bronchial asthma and reversible bronchospasm associated with chronic bronchitis and emphysema.

How should I take duralyn CR (theophylline)?

Duralyn CR comes as a capsule. Swallow it whole. Do not crush or chew. Drink with a glass of water. May be taken with meals to reduce GI discomfort.

Some foods may change the effectiveness or increase the side effects of theophylline. Talk to your doctor about how you should take theophylline with regard to food. Do not suddenly change your diet or eating habits without first checking with your doctor.

Take theophylline at evenly spaced times throughout the day. Taking theophylline at the same time each day will help you remember to take it. Contact your doctor with any questions or concerns about the best way to take theophylline.

How do I store duralyn CR (theophylline)?

Duralyn CR is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store duralyn CR in the bathroom or the freezer. There may be different brands of duralyn CR that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush duralyn CR down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using duralyn CR (theophylline)?

Before using this drug, tell your doctor if:

  • You are pregnant, planning to become pregnant, or are breastfeeding.
  • You are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement.
  • You have allergies to medicines, foods, or other substances.

This drug is contraindicated in case of:

  • Hypersensitivity to any xanthine
  • Peptic ulcer
  • Underlying seizure disorders (unless receiving appropriate anticonvulsant medication)

Status asthmaticus is a medical emergency and is not rapidly responsive to usual doses of conventional bronchodilators. Oral theophylline products alone are not appropriate for status asthmaticus.

Theophylline may cause dysrhythmias or worsen preexisting arrhythmias. Any significant change in cardiac rate or rhythm warrants monitoring and further investigation.

Theophylline should not be administered concomitantly with other xanthines.

Is it safe during pregnancy or breastfeeding?

There are no adequate studies in women for determining risk when using duralyn CR during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking duralyn CR. Duralyn CR is pregnancy risk category C, according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk
  • B=No risk in some studies
  • C=There may be some risk
  • D=Positive evidence of risk
  • X=Contraindicated
  • N=Unknown

Side effects

What side effects can occur from duralyn CR (theophylline)?

Some side effects may occur when using this drug, such as:

  • Nausea
  • Vomiting
  • Epigastric pain
  • Diarrhea
  • Headache
  • Irritability
  • Insomnia
  • Muscle twitching
  • Clonic
  • Tonic generalized convulsions
  • Palpitation
  • Tachycardia
  • Extrasystoles
  • Flushing
  • Hypotension
  • Ventricular arrhythmias
  • Tachypnea
  • Potentiation of diuresis
  • Alopecia
  • Rash

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.


What drugs may interact with duralyn CR (theophylline)?

Duralyn CR may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Products may interact with this drug, including:

  • Aminoglutethimide, barbiturates (e.g., phenobarbital), carbamazepine, hydantoins (e.g., phenytoin), isoproterenol, moricizine, rifampin, St. John’s wort, or sulfinpyrazone, because they may decrease theophylline’s effectiveness
  • Allopurinol, beta-blockers (e.g., propranolol), cimetidine, disulfiram, enoxacin, estrogen, febuxostat, fluvoxamine, interferon alpha, macrolide antibiotics (e.g., clarithromycin, erythromycin), methotrexate, mexiletine, oral contraceptives (birth control pills), pentoxifylline, propafenone, quinolone antibiotics (e.g., ciprofloxacin), tacrine, thiabendazole, ticlopidine, troleandomycin, verapamil, viloxazine, or zileuton, because they may increase the risk of theophylline’s side effects.
  • Ephedrine, because the risk of side effects, such as nausea, nervousness, and trouble sleeping, may be increased.
  • Halothane, because the risk of side effects such as irregular heartbeat may be increased.
  • Ketamine, because the risk of seizures may be increased.
  • Adenosine, benzodiazepines (e.g., diazepam, flurazepam, lorazepam, midazolam), dipyridamole IV, lithium, or nondepolarizing muscle relaxants (e.g., pancuronium), because their effectiveness may be decreased by theophylline.

Does food or alcohol interact with duralyn CR (theophylline)?

Duralyn CR may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with duralyn CR (theophylline)?

Duralyn CR may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.

Especially, you have:

  • A history of heart problems (e.g., congestive heart failure, cor pulmonale)
  • An irregular heartbeat
  • Liver problems (e.g., cirrhosis, hepatitis)
  • Viral infection
  • Thyroid problems
  • Increased acid levels in the body
  • Brain
  • Nerve problems
  • Seizures (e.g., epilepsy)
  • Shock
  • Fever
  • A peptic ulcer
  • A severe infection
  • Cystic fibrosis
  • Fluid in the lungs (pulmonary edema)
  • Hyperemia
  • Hypertension
  • Cardiac disease
  • Congestive heart failure
  • Alcoholism


The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using duralyn CR (theophylline).

What is the dose of duralyn CR (theophylline) for an adult?

The recommended dose is 1 cap daily, preferably between 6-8 PM (because of circadian rhythm).

What is the dose of duralyn CR (theophylline) for a child?

The dosage has not been established in pediatric patients under 12 years old. It may be unsafe for your child. It is always important to fully understand the safety of the drug before using. Please consult with your doctor or pharmacist for more information.

How is duralyn CR (theophylline) available?

Duralyn CR is available in the following dosage forms and strengths:

  • Duralyn CR Capsules 200 mg

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of duralyn CR, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

msBahasa Malaysia

Review Date: April 1, 2017 | Last Modified: September 12, 2019

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