Veterinary Drug Handbook (VDH) is the reference veterinarians turn to when they want an independent source of information on the drugs that are used in veterinary medicine today.


Doses - DIPHENHYDRAMINE HCL

Dogs:

Prevention of motion sickness/antiemetic:
a) 2 - 4 mg/kg PO, IM q8h (Washabau and Elie 1995)
b) 2 - 4 mg/kg PO q8h (DeNovo 1986)
For treatment of extrapyrimidal effects secondary to phenothiazines:
a) 2 - 5 mg/kg IV (Bailey 1986)
For adjunctive treatment (of tremors) secondary to organophosphate or carbamate poisoning:
a) 4 mg/kg PO (Carson 1986)
b) 1 - 4 mg/kg PO tid (reduces nicotinic receptor overload) (Grauer and Hjelle 1988) For prevention of allergic reactions secondary to doxorubicin therapy:
a) For dogs up to 20 lbs = 10 mg IV;for dogs 20 - 60 lbs = 20 mg IV;for dogs over 60 lbs. = 30 mg IV. Give prior to doxorubicin administration. (Klausnerand Bell 1988)
b) 1 mg/kg IV with 5 mg/kg cimetidine before therapy. (Coppoc 1988)
For severe urticaria and angioedema:
a) 2 mg/kg IM bid prn (with steroids: prednisone 2 mg/kg IM bid and epinephrine1:10, 000: 0.5 - 2.0 ml SQ) (Giger and Werner 1988)
For canine atopy/allergic inhalant dermatitis:
a) 2 mg/kg PO tid (effectiveness is questionable, but may be tried) (Giger and Werner1988)
For preoperative therapy for splenic mast cell tumors:
a) 2.2 mg/kg IM bid (with cimetidine 5 mg/kg PO, IV tid-qid) (Stann 1988)
For treatment of the reverse sneeze syndrome:
a) 25 mg PO tid -qid, dosage is usually decreased to once or twice a week for maintenance.(Prueter 1988a)
As an antipruritic:
a) 25 - 50 mg PO bid-tid (Morgan 1988)

Cats:

For severe urticaria and angioedema:
a) 2 mg/kg IM bid prn (with steroids: prednisone 2 mg/kg IM bid and epinephrine1:10, 000: 0.5 - 2.0 ml SQ) (Giger and Werner 1988)
Prevention of motion sickness/antiemetic:
a) 2 - 4 mg/kg PO, IM q8h (Washabau and Elie 1995)
b) 2 - 4 mg/kg PO q8h (DeNovo 1986)

Horses:

For adjunctive therapy of anaphylaxis:
a) 0.25 - 1 mg/kg IV or IM (Evans 1996)

Cattle:

For adjunctive therapy of anaphylaxis:
a) 0.5 - 1 mg/kg IM or IV (used with epinephrine and steroids) (Clark 1986)
For adjunctive therapy of aseptic laminitis:
a) During the acute phase (with corticosteroids): 55 - 110 mg/100 kg body weight IV or IM (Berg 1986)
Monitoring Parameters -
1) Clinical efficacy and adverse effects
Client Information/FDA Approval Status - Diphenhydramine is approved for use in humans.
The oral dosage forms are either prescription or non-prescription agents, depending on the product's labeling. The injectable products are prescription only.
Dosage Forms/Preparations - Veterinary-Approved Products: None

Human-Approved Products:

Diphenhydramine HCl Capsules 25 mg, 50 mg; 12.5 mg chewable) & 50 mg Tablets
Diphenhydramine HCl Oral Elixir or Syrup 12.5 mg/5 ml (2.5 mg/ml) in 4 oz, pint and gallonbottles
Diphenhydramine Injection 10 mg/ml in 10 ml or 30 ml vials; 50 mg/ml in 1 ml amps and 10 mlvials
Diphenhydramine is available under several trade names; a commonly known product is Benadryl® (Parke-Davis).
Diphenoxalate HCl/Atropine - see Opiate Antidiarrheals
Diphenylhydantoin - see Phenytoin