[129] PLASMA NELFINAVIR CONCENTRATIONS ARE SIGNIFICANTLY LOWER IN PREGNANCY

2nd International AIDS Society Conference on HIV Pathogenesis and Treatment

Paris, France - July 13 - 16, 2003

[TITLE:] PLASMA NELFINAVIR CONCENTRATIONS ARE SIGNIFICANTLY LOWER IN PREGNANCY

[AUTHOR(S):] F Wit², J Nellen¹, A Bergshoeff³, D Burger³, M Godfried¹, K Boer¹, J Lange¹ and J Prins¹
¹Academic Medical Centre, Amsterdam; ²International Antiviral Therapy Evaluation Center, Amsterdam; and ³University Hospital Nijmegen, Nijmegen, the Netherlands

IAS Conf HIV Pathog Treat 2003 Jul 13-16;2nd: Abstract No. 129
Antiviral Therapy 2003; 8(Suppl. 1):S215

[ABSTRACT:] Background: Because of its relative safety, nelfinavir (NFV) is often used as part of HAART during pregnancy to prevent mother-to-child transmission of HIV. Drug levels of NFV should be monitored, as concentration ratios below 0.9 are associated with virological failure. It is unknown whether pregnancy affects NFV drug levels.

Methods: We analysed all NFV plasma levels taken since 1998 in women of our outpatient clinic. Standard dosage of NFV is 1250 mg BID. From every pregnant patient the first ever-measured drug level obtained was included in the analysis. The concentration ratio (CR) was calculated by dividing the measured concentration by a reference population value at the corresponding sampling time.

Results: We analysed drug levels from 67 patients: 19 were taken during pregnancy and 48 not during pregnancy. 12/19 (63%) of the CRs during pregnancy (CRpr) were below 0.9 compared to 16/48 (33%) of CRs in non-pregnant women (CRnp) (Fishers’ Exact Test, P=0.032). When a CR<0.7 was taken as a cut-off, 10/19 (53%) pregnant patients and 12/48 (25%) non-pregnant women had low plasma levels (Fishers’ Exact Test, P=0.044). The median CR was 0.70 in pregnant women versus 1.06 in non-pregnant women (Wilcoxon, P=0.009). This also suggests that plasma concentrations in non-pregnant women are comparable with those of the male white reference population. 39 women were from African origin, 27 Caucasian and one woman was Asian (no significant differences between pregnant and non-pregnant women). In both a logistic and linear regression analysis only pregnancy was (and race and age were not) found to significantly influence the CRs.

Conclusions: Non-pregnant females have similar NFV CRs as the male white reference population. Race did not influence the NFV CR in women. Pregnancy is associated with markedly decreased NFV concentrations. Drug levels in pregnant women should be carefully monitored.

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