What is theophylline?
Theophylline (brand names: Theo-24®, Theochron®, Elixophyllin®, Theodur®) is a bronchodilator used to treat cough caused by bronchospasm or bronchoconstriction (tightening or narrowing of the airways in the lungs). It also has mild diuretic effects.
Its use in cats and dogs to treat cough and bronchoconstriction is off label (extra label). Many drugs are commonly prescribed for off-label use in veterinary medicine.
“Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.
How is theophylline given?
- Theophylline is given by mouth in the form of a tablet or liquid. It may also be given as an injection by your veterinarian in the hospital.
- Do not crush or break the tablets or allow your pet to chew them.
- Theophylline can be given with or without food.
- If stomach upset occurs on an empty stomach, give the medication with food.
This medication should take effect within 1 to 2 days, and you should see improvements in your pet’s clinical signs.
What if I miss giving my pet the medication?
If you miss a dose, give it as soon as you remember, and then continue with the regular dosing schedule. However, if it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once.
Are there any potential side effects?
Theophylline may cause the following side effects:
- Central nervous system stimulation (excitement)
- Stomach or intestinal irritation, such as nausea, vomiting, and diarrhea
- Sleeplessness
- Increased drinking, eating, and urinating
Serious adverse reactions may occur but are rare and may indicate that the dose is too high. If any of the following signs develop, stop giving theophylline and contact your veterinarian immediately:
- Seizures
- Collapse
Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver disease or congestive heart failure.
Are there any risk factors for this medication?
DO NOT USE theophylline in pets that:
- Are sensitive or allergic to it or related substances, such as theobromine, aminophylline, or caffeine
- Are pregnant or nursing (unless the benefits outweigh the risks)
USE WITH CAUTION in pets that:
- Have severe heart disease or abnormal heart rhythms
- Have seizures
- Have stomach ulcers
- Have hyperthyroidism
- Have kidney or liver disease
- Have severely high blood pressure
- Have severely low blood oxygen levels
- Are very young or very old pets (toxic effects are more likely)
- Have liver disease or heart failure (these pets should receive lower doses of the medication)
Are there any drug interactions I should be aware of?
Several medications should be used with caution when given with theophylline, including:
- Activated charcoal
- Barbiturates
- Benzodiazepines
- Beta-blockers
- Calcium channel blockers
- Cimetidine
- Corticosteroids
- Fluoroquinolones
- Ketoconazole
- Loop diuretics
- Macrolides
- Sympathomimetics
- Thyroid hormones
Certain medications may interact with theophylline, so be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.
Is any monitoring needed with this medication?
- At home, monitor for any side effects such as those noted above. If any occur, stop using the medication and contact your veterinarian.
- Your veterinarian will let you know when and how they want to reassess your pet to ensure the medication is working and not causing side effects.
- In some cases, blood levels of the medication may be monitored to be sure the dose is correct.
How do I store theophylline?
- Store theophylline tablets and oral liquid at room temperature, below 30°C (86°F).
- Store in a tightly closed container.
What should I do in case of emergency?
If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet's weight and symptoms.
