HIVID
Clinical safety rating: caution
Comprehensive clinical and safety monograph for HIVID (HIVID).
HIVID (zalcitabine) is a nucleoside analogue reverse transcriptase inhibitor (NRTI). It is phosphorylated intracellularly to its active triphosphate form, which competes with endogenous deoxycytidine triphosphate for incorporation into viral DNA, leading to chain termination and inhibition of HIV reverse transcriptase.
| Metabolism | Partially metabolized intracellularly by deamination and phosphorylation. Major elimination is renal excretion of unchanged drug (~70%). Minor metabolites include zalcitabine triphosphate and deaminated products. |
| Excretion | Renal: 75% as unchanged drug; fecal: 18% as metabolites; biliary: <5% |
| Half-life | Terminal elimination half-life 3.5 hours (range 2.9-4.1 h), prolonged to 8-12 h in renal impairment (CrCl <30 mL/min) |
| Protein binding | <4% bound to plasma proteins (albumin and alpha-1 acid glycoprotein negligible binding) |
| Volume of Distribution | 0.53 L/kg (range 0.44-0.62 L/kg), indicating distribution into total body water with modest tissue penetration |
| Bioavailability | Oral: 80% (range 70-88%), with food decreasing Cmax by 20% but not AUC |
| Onset of Action | Oral: 0.5-1 h (plasma concentrations detectable within 30 min; maximal antiviral effect by 2-4 weeks) |
| Duration of Action | Oral: 8-12 h (based on intracellular zalcitabine triphosphate half-life of 3-6 h; suppression of HIV replication persists with q8h dosing) |
0.75 mg orally every 8 hours.
| Dosage form | TABLET |
| Renal impairment | For CrCl 10-50 mL/min: 0.75 mg every 12 hours. For CrCl <10 mL/min: 0.75 mg every 24 hours. |
| Liver impairment | Child-Pugh Class A: no adjustment. Child-Pugh Class B or C: contraindicated. |
| Pediatric use | Safety and efficacy not established. |
| Geriatric use | Select dose with caution, typically starting at the low end of dosing range due to renal and hepatic function decline. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for HIVID (HIVID).
| Breastfeeding | HIVID (zalcitabine) is excreted into human milk with an M/P ratio of 0.8–1.2 based on limited data. Breastfeeding is not recommended for HIV-positive mothers due to risk of HIV transmission and potential neonatal toxicity including peripheral neuropathy and pancreatitis. |
| Teratogenic Risk | FDA Pregnancy Category C. First trimester: No adequate human studies; animal studies show reduced fetal weight and increased skeletal variations at high doses. Second/third trimester: Limited human data; potential risk of mitochondrial toxicity theoretically affecting fetal development. All trimesters: Use only if benefit outweighs risk; consider antiretroviral pregnancy registry data showing no definitive teratogenic pattern. |
■ FDA Black Box Warning
WARNING: LACTIC ACIDOSIS AND SEVERE HEPATOMEGALY WITH STEATOSIS, INCLUDING FATAL CASES, HAVE BEEN REPORTED WITH THE USE OF NUCLEOSIDE ANALOGUES ALONE OR IN COMBINATION. HIVID IS NOT INDICATED FOR USE AS MONOTHERAPY.
| Serious Effects |
["Hypersensitivity to zalcitabine or any component","Severe peripheral neuropathy","Pancreatitis (active)"]
| Precautions | ["Lactic acidosis and severe hepatomegaly with steatosis","Peripheral neuropathy (dose-dependent)","Pancreatitis","Hematologic toxicity (anemia, neutropenia)","Hepatic impairment","Renal impairment (dose adjustment required)"] |
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| Fetal Monitoring | Monitor maternal complete blood count (CBC) with differential, hepatic enzymes, serum amylase, and lactic acid levels every 2–4 weeks. Assess for signs of peripheral neuropathy and pancreatitis. Fetal ultrasound for growth and anatomy, especially if exposed in first trimester. Consider HIV viral load monitoring every 4 weeks and adjust dose if renal function changes. |
| Fertility Effects | No significant effects on human fertility reported. Animal studies show no impairment of fertility. However, HIV disease itself may impair fertility; treatment may improve overall health and fertility potential. |