Brand Name: Elavil
Available in 10 mg, 25 mg, 50 mg, 75 mg, 100 mg, and 150 mg tablets
Background
Amitriptyline was developed out of a need in human medicine for anti-anxiety medications to treat mental illness. In humans, it has also gained some popularity for the treatment of chronic pain syndromes, especially interstitial cystitis.
This medication creates its effects via several mechanisms:
- By blocking the way cells of the nervous system transport biochemicals called amines, amitriptyline is able to increase the levels of circulating neurotransmitters, especially a neurotransmitter called serotonin. This mechanism seems to be at the route of amitriptyline‘s anti-anxiety and psychoactive properties. In humans, this medication is used in the treatment of anxiety, bipolar disorders, and depression. This property also is responsible for amitriptyline‘s sedation side effect.
- The same blockage of the amine pump leads to increased levels of the neurotransmitter norepinephrine. Norepinephrine is an important neurotransmitter in the sympathetic nervous system as described below.
- Amitriptyline is a strong antihistamine.
- Amitriptyline also has what are called anticholinergic effects, which requires some explanation. The part of the nervous system that regulates an assortment of involuntary operations is called the autonomic nervous system. It is divided into two areas: the sympathetic system, which is responsible for generating changes during a fight or flight situation (such changes include increased circulation to muscles, increased heart rate, pupil dilation etc.) and the parasympathetic nervous system, which is responsible for maintaining the body’s status quo. The parasympathetic system uses acetylcholine as its chief neurotransmitter. An anticholinergic medication, disrupts acetylcholine and creates side effects such as dry mouth, urinary retention, constipation, dried respiratory secretions.
Amitriptyline is a member of the class of drugs called tricyclic antidepressants.
How this Drug is Used
With amitriptyline becoming widely used in human mental illness, it was not long before small animal uses for this medication came to light. Amitriptyline has been used in animals for separation anxiety, for inappropriate urination in cats, for feline lower urinary tract disease, and for obsessive grooming behaviors in both dogs and cats. In many of these conditions it is not clear which of the above described mechanisms of action are responsible for the desired effects.
Side Effects
The most common side effect is drowsiness/sedation.
Anticholinergic side effects would probably not be surprising: dry mouth (manifested in animals often as frequently licking of the lips), urinary retention, constipation.
The most potentially dangerous side effect that happens with a realistic frequency is the exacerbation of a cardiac rhythm disturbance.
For this reason, an EKG screening has been recommended before starting this medication.
Tricyclic antidepressants can alter blood sugar levels.
In humans, side effects in virtually every organ system have been reported at one time or another, which means that potentially any side effect could be attributed to the use of this medication.
Interactions with other Medications
Tricyclic antidepressants such as amitriptyline cannot be safely used with monoamine oxidase inhibitors such as Deprenyl (Anipryl®).
The risk of developing a dangerously low white blood cell count with the use of methimazole is greatly increased if there is concurrent use of amitriptyline.
The use of cimetadine (Tagamet®) can interfere with the desired effect of amitriptyline.
Amitriptyline is best not used in conjunction with other drugs with anticholinergic effects, drugs that stimulate the sympathetic nervous system, or with other psychoactive drugs.
Concerns and Cautions
Amitriptyline is removed from the body through the liver. Patients with abnormal liver function may have trouble with this medication. Periodic liver enzyme evaluation (blood testing) is a good idea for patients on this medication long term.
Amitriptyline should not be used during pregnancy or lactation, in patients with seizure disorders, or in patients with cardiac rhythm disturbances.
Diabetic pets should avoid the use of amitriptyline.
It is our policy not to give dosing information over the Internet.
Date Published: 9/10/2001
Date Reviewed/Revised: 09/01/2009
