Trial reportClinical pharmacokinetics2004
Reduction of saquinavir exposure by coadministration of loperamide: a two-way pharmacokinetic interaction.
Trial report in Clinical pharmacokinetics, 2004. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
2 citing papers in PubMed, 9 citations in OpenAlex.
- Managing Drug-Drug Interactions Involving the Non-Prescription Opioid Loperamide Through Physiologically Based Pharmacokinetic Modeling.CPT: pharmacometrics & systems pharmacology · 2026Article
- Association of the CYP3A5 A6986G (CYP3A5*3) polymorphism with saquinavir pharmacokinetics.British journal of clinical pharmacology · 2004Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
8 authors at 1 institution in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
objectiveTo assess any pharmacokinetic interactions between loperamide and saquinavir.
designDouble-blind, double-dummy, randomised, placebo-controlled, three-way crossover trial.
participantsTwelve healthy male and female volunteers, aged 24-46 years.
methodsSaquinavir and loperamide pharmacokinetics were determined over a 72-hour period after single dose administration of saquinavir 600mg and/or loperamide 16mg. Plasma and urine concentrations of loperamide, its metabolites, and saquinavir were analysed using a single liquid chromatography/tandem mass spectrometry method for all compounds.
resultsSaquinavir exposure was reduced by 54% when given with loperamide (median area under the concentration-time curve from zero to infinity [range], 1189 [243-2113] vs 550 [234-1468] pmol . h/mL; p = 0.016) with unchanged renal clearance. In contrast, loperamide concentrations increased and desmethylloperamide concentrations decreased during saquinavir coadministration, resulting in a reduced metabolic clearance of loperamide (median [range], 544 [224-1393] vs 443 [238-692] mL/min; p = 0.016).
conclusionsWhereas the effect of saquinavir on loperamide disposition is unlikely to be of clinical relevance, the reduced drug exposure of saquinavir when loperamide is coadministered is worrisome because a relationship between protease inhibitor drug exposure and antiviral response has been reported. Patients receiving saquinavir monotherapy should be advised not to combine these drugs, especially for prolonged periods of time because a reduction in therapeutic efficacy may result.
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Registered trials
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