THE PET PHARMACY By Wendy C. Brooks, DVM, DipABVP Educational Director, VeterinaryPartner.com

(for veterinary information only)

Brand Name: Hycodan, Tussigon or Mycodone

Available in oral liquid, and syrup (tablets no longer available)

Background

Narcotics are able to bring about many bodily effects beyond the notorious addictive euphoria.  Other effects the medical profession has been interested in include: analgesia, anti-diarrheal effects, cardiovascular effects, and cough suppression. Hydrocodone represents a narcotic developed to accentuate the cough suppression effect.  It is somewhat more effective in this regard than codeine (another famous narcotic with strong cough suppression effects). Cough suppression by narcotics is created by direct action on the cough centers of the brain.

Hydrocodone also tends to dry respiratory secretions, a desirable effect in benign minor infections (see below).  This effect is further accentuated with the addition of a substance called homatropine; however, one of the chief reasons why homatropine is added to hydrocodone is to prevent abuse of its narcotic effects. Should someone attempt to consume more than a recommended dose of hydrocodone (and homatropine), some very unpleasant side effects of homatropine will prevent gross overconsumption.

How this Medication is Used

Some typical situations in which cough suppression with hydrocodone would be helpful include:

• Kennel cough (a usually minor infection leading to bronchitis).
  
• Collapsing trachea (where the windpipe becomes flimsy).
  
• "Old dog" bronchitis (a natural part of aging in dogs involves excess mucus production in the lungs).
  
• Heart enlargement (where the right chambers of the heart become so large that as the heart beats they pinch off the main airways)

These are all conditions where minor secretions or actual tissues are pressing on the lung's airways and stimulating cough.  Coughs that benefit from suppression are typically dry and hacking, often described as sounding as though something is stuck in the throat.

The effect of hydrocodone in a dog is believed to last approximately 6 to 12 hours. It is typically dosed at four times a day usage or less, as needed.

Side Effects

The chief side effects of hydrocodone use include:

     •     Drowsiness or tranquilization
 
     •     Drying of respiratory secretions
 
     •     Constipation (if hydrocodone is given chronically)
 
     •     Upset stomach

Notify your veterinarian if any of these side effects appear to be causing patient discomfort.

Interactions with other Drugs

Serious side effects have been reported involving interactions between Anipryl/L-Deprenyl (treatment for "senility" in dogs as well as for <%= InternalLink:A:1193:Cushing's disease%> in dogs) and Demerol (another narcotic).  Based on this, the recommendation to avoid the use of Anipryl/L-deprenyl with any narcotics has been proposed; a different cough suppressant should be sought in such cases.

It is best not to mix hydrocodone with other tranquilizers or with antihistamines.

Concerns and Cautions

• Cough suppression is not appropriate in the event of pneumonia. In pneumonia, there is excessive pus and mucus accumulation in the lung and this material must be coughed up.  Suppressing the cough and drying the secretions will hinder the body's removal of this septic material.
  
• Narcotic cough suppressants should be avoided in cases involving obstructive diarrheas or toxic diarrheas (such as canine parvovirus infection). The narcotic will improve the intestinal tone, which will assist in the absorption of water from the bowel and will improve stool consistency; however, it will also facilitate toxic absorption as well. In such situations, other forms of diarrhea treatment would be more appropriate.

It is our policy not to give dosing information over the Internet.

Date Published: 1/1/2001
Date Reviewed/Revised: 12/15/2008