Study of the Pharmacokinetics of Intravenous Administered 14C-MNTX

An Open-Label, Phase I, Single Dose Study of the Pharmacokinetics, Mass Balance and Disposition of Intravenously Administered 14C-Methylnaltrexone in Normal, Healthy Volunteers

Status

Completed

Phases

Phase 1

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT01367483

Enrollment

Registered

2011-06-07

Start date

2005-06-30

Completion date

2005-06-30

Last updated

2019-11-27

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Healthy Male Volunteers

Brief summary

This is an open-label, radiotracer study, to be conducted in healthy, normal, male volunteers. It will entail intravenous administration of a single dose of 14C-MNTX, collection of excretions, and periodic drawing of blood samples. Exhaled 14CO2 will also be sampled as a measure of the extent of possible metabolic MNTX demethylation.

Interventions

DRUGIV methylnaltrexone (MNTX)

Study design

Allocation

NON_RANDOMIZED

Intervention model

SINGLE_GROUP

Primary purpose

TREATMENT

Masking

NONE

Eligibility

Sex/Gender

MALE

Age

18 Years to 45 Years

Healthy volunteers

Yes

Inclusion criteria

1. Males between 18-45 2. Subject weight between 70 and 90 kg 3. In good physical health, with no evidence at screening of acute or chronic disease likely to affect the investigation

Exclusion criteria

1. History or evidence of cardiovascular, gastrointestinal, hepatic, neurological, pulmonary, renal, or other significant chronic condition. 2. Consumption of barbiturates or other inducers or inhibitors of CYP450 isoforms 3. History of or predisposition to erratic or abnormal bowel function.

Design outcomes

Primary

Measure	Time frame	Description
Peak Plasma and Whole Blood Concentration (Cmax) of IV MNTX	5.5 days	To study the pharmacokinetics of MNTX following a single IV dose of 14C-MNTX in normal, healthy volunteers.

Secondary

Measure	Time frame	Description
Time to Maximum (Tmax) in Plasma and Whole Blood Concentration of IV MNTX	5.5 Days	To study the pharmacokinetics of MNTX following a single IV dose of 14C-MNTX in normal, healthy volunteers.
Clearance of IV MNTX	5.5 days	To study the pharmacokinetics of MNTX following a single IV dose of 14C-MNTX in normal, healthy volunteers.
Half-life of IV MNTX	5.5 days	To study the pharmacokinetics of MNTX following a single IV dose of 14C-MNTX in normal, healthy volunteers.
Volume of Distribution of IV MNTX	5.5 days	To study the pharmacokinetics of MNTX following a single IV dose of 14C-MNTX in normal, healthy volunteers.
Urinary Clearance of IV MNTX	5.5 days	To study the pharmacokinetics of MNTX following a single IV dose of 14C-MNTX in normal, healthy volunteers.

Countries

United States

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026