Dichlorphenamide

By | 2010-08-30

Chemistry

A carbonic anhydrase inhibitor, dichlorphenamide occurs as a white or nearly white, crystalline powder with a melting range of 235-240°C, and pKas of 7.4 and 8.6. It is very slightly soluble in water and soluble in alcohol.

Storage – Stability – Compatibility

Store tablets in well-closed containers and at room temperature. An expiration date of 5 years after the date of manufacture is assigned to the commercially available tablets.

Pharmacology

See the discussion listed in the acetazolamide monograph immediately prior to this one.

Uses – Indications

Dichlorphenamide is used for the medical treatment of glaucoma.

Pharmacokinetics

The pharmacokinetics of this agent have apparently not been studied in domestic animals. One report states that after a dose of 2.2 mg/kg, the onset of action is 30 minutes, maximal effect in 2-4 hours, and duration of action is 6-12 hours in small animals.

Contraindications/Precautions, Adverse Effects/Warnings, Overdosage, & Drug Interactions

See the discussion in the acetazolamide monograph found immediately prior to this one.

Doses

Doses for dogs:

a) 2 – 5 mg/kg PO q8h

b) 10 – 15 mg/kg per day divided 2-3 times daily

c) 2 – 5 mg/kg PO divided tid

d) 2 – 4 mg/kg PO bid-tid

Doses for cats:

a) 10 – 25 mg (total) q8h PO

b) 1 mg/kg PO bid-tid

Monitoring Parameters

1) Intraocular pressure/tonometry

2) Serum electrolytes

3) Baseline CBC with differential and periodic retests if using chronically.

4) Other adverse effects

Client Information

If GI upset occurs, give with food. Notify veterinarian if abnormal bleeding or bruising occurs or if animal develops tremors or a rash.

Dosage Forms – Preparations – FDA Approval Status – Withholding Times

Veterinary-Approved Products:

None

Human-Approved Products:

At the time this edition went to press, there were rumors that the manufacturer was discontinuing this product and it may not be available.

Dichlorphenamide 50 mg Tablets (scored); Daranide® (Merck); (Rx)