DrugindexOnline^{2nd edition}

( Dideoxycytidine ; ddC ) Pronouncation: (zal-SITE-uh-BEAN)
Class: Nucleoside reverse transcriptase inhibitor

Trade Names:
Hivid
- Tablets 0.375 mg
- Tablets 0.75 mg

Mechanism of Action

Pharmacology

Inhibits replication of DNA in HIV.

Pharmacokinetics

Absorption

Oral bioavailability is about 80%. Absorption rate of a 1.5 mg oral dose was reduced with food. C _max is 25.2 ng/mL. T _max is 0.8 hr. AUC is 72 ng•hr/mL.

Distribution

Vd is 0.534 L/kg. Less than 4% protein bound. Drug interaction involved in binding site is unlikely.

Metabolism

Major metabolite is dideoxyuridine.

Elimination

Renal elimination is the primary route of elimination. The t _½ is about 2 hr.

Special Populations

Renal Function Impairment

Prolonged elimination may be expected.

Children

Mean bioavailability is 54%.

Indications and Usage

Combination therapy

For the treatment of selected patients with advanced HIV infection.

Contraindications

Standard considerations.

Dosage and Administration

Combination therapy
Adults and Adolescents more than 13 yr

PO 0.75 mg (coadministered with other antiviral agents) q 8 hr (total daily dose 2.25 mg zalcitabine).

Storage/Stability

Store at room temperature in tight containers.

Drug Interactions

Aminoglycosides, amphotericin, foscarnet

May increase risk of peripheral neuropathy and other zalcitabine toxicities caused by decreased clearance of zalcitabine.

Chloramphenicol, cisplatin, dapsone, disulfiram, ethionamide, glutethimide, gold, hydralazine, iodoquinol, isoniazid, metronidazole, nitrofurantoin, phenytoin, ribavirin, vincristine

May increase risk of peripheral neuropathy.

Drugs associated with pancreatitis (eg, pentamidine)

Fatal pancreatitis has occurred, possibly related to zalcitabine and IV pentamidine given concurrently.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Chest pain; cardiomyopathy; CHF.

CNS

Headache; dizziness; confusion; impaired concentration; peripheral neuropathy.

Dermatologic

Rash; pruritus; dermatitis.

EENT

Pharyngitis.

GI

Pancreatitis; oral ulcers; nausea; dysphagia; anorexia; abdominal pain; vomiting; diarrhea; dry mouth; esophageal ulcers; dyspepsia; glossitis.

Metabolic

Weight decrease; weight gain; increased amylase; hyperglycemia; hyponatremia; hypoglycemia; loss of appetite.

Respiratory

Nasal discharge; cough; respiratory distress.

Miscellaneous

Myalgia; arthralgia; foot pain; fatigue; anaphylactoid reaction; abnormal GGT.

Precautions

Warnings Hepatitis B Hepatic failure and death, possibly related to underlying hepatitis B and zalcitabine, have been reported. Lactic acidosis and hepatomegaly Have been reported with steatosis (including fatal cases) reported with the use of nucleoside analogues alone or in combination with other antiretrovirals. Neuropathy Severe peripheral neuropathy, use with extreme caution in patients with preexisting neuropathy. Pancreatitis Rarely occurs; monitor.

Pregnancy

Category C .

Lactation

Undetermined. It is recommended that HIV-positive women do not breast-feed.

Children

Safety and efficacy in children less than 13 yr not established.

Renal Function

Patients with renal impairment (Ccr less than 55 mL/min) may be at greater risk of toxicity because of decreased drug clearance. Dosage reduction may be needed.

Hepatic Function

In patients with history of liver disease or alcoholism, zalcitabine may exacerbate hepatic dysfunction. Dosage reduction or interruption of therapy may be needed.

Anaphylactoid reaction

Anaphylactoid reaction has occurred. Urticaria has occurred without other signs of anaphylaxis.

Cardiomyopathy/CHF

Cardiomyopathy/CHF may develop. Use drug with caution in patients with history of cardiomyopathy or CHF.

Esophageal ulcers

Esophageal ulcers have occurred.

HIV infection complications

Patients receiving zalcitabine or any other antiretroviral therapy may continue to develop opportunistic infections and other complications of HIV infection.

Overdosage

Symptoms

Rash, fever, peripheral neuropathy.

Patient Information

• Advise patient to take around the clock as prescribed and not to increase the dose.
• Advise patient not to share the drug with others.
• Inform patient and family that patient may continue to develop opportunistic infections and other complications of HIV infection and should remain under close medical supervision.
• Explain that zalcitabine is not a cure but may offer symptomatic improvement.
• Reinforce fact that zalcitabine does not decrease risk of transmission of HIV through sexual contact or blood contamination.
• Instruct patient to notify health care provider immediately of signs of peripheral neuropathy (numbness and burning feeling in arms and legs) or pancreatitis (abdominal pain, nausea, vomiting).
• Encourage patient to report all changes in conditions to health care provider.
• Inform patient that long-term effects of this drug alone and in combination with zidovudine are unknown.