posttransplant; an ANC of 200 by day 21 posttransplant; and an ANC 
of 500 by day 29 posttransplant. 
Untoward side effects or other organ impairment thought to be secondary to 
Zidovudine administration, such as neuropathy and myopathy. 
Guidelines for Reducing Zidovudine Schedule 
Neutropenia: Neutropenia is an expected occurrence in BMT and is observed 
during the engraftment period (day 0 through day 28), and is often observed 
again between days +50 through +70 in 25% of patients. 
The Zidovudine dose (oral or IV) should be reduced by one-third (TV dose: 
1.5 mg/kg every four hours; oral dose: 100 mg every six hours) in patients 
with a persistent decline in peripheral neutrophil count after initial engraftment 
(below 500 neutrophils/mm 3 ) between days +30 and + 100 (Table 3). A peak 
and trough Zidovudine serum level should be obtained prior to the dose 
reduction and again at forty-eight hours after the dose reduction. A second 
dose reduction may be made after an additional seven days if the neutrophil 
count remains < 500 cells/mm 3 and bone marrow aspirate does not indicate 
early recovery of myeloid elements. At this time the dose should be further 
reduced (IV dose: 1.13 mg/kg; oral dose: 50 mg every four hours), and 
serum Zidovudine peak and trough levels should again be obtained after forty- 
eight hours. If after an additional seven days the neutrophil count remains 
< 500 cells/mm 3 , then Zidovudine should be discontinued. When the 
neutrophil count rises above 500 cells/mm 3 the full Zidovudine dosing 
schedule should be restarted. 
TABLE 3 
Guidelines for Dose Reduction of Zidovudine after day 30 posttransplant 
CONDITION 
Dose 
IV 
PO 
1 . 
ANC >500 
2.25 mg/kg q. 4 hrs. 
100 mg.p.o. q. 4 hrs. 
2. 
1st dose 
reduction: 
1.5 mg/kg q. 4 hrs. 
100 mg. p.o. q. 6 hrs. 
3. 
ANC <500 
2nd dose 
reduction: 
1.13 mg/kg q. 4 hrs. 
50 mg. q. 4 hrs. 
ANC <500/ 
1 week after 
first dose 
reduction 
4. Discontinuation: 
ANC <500/1 week 
after second dose 
reduction 
Subjects with neutropenia after day + 100 (<500 cells/mm 3 ) should have Zidovudine peak 
b. 
c. 
Recombinant DNA Research, Volume 15 
[625] 
