Study of the Pharmacokinetics of Intravenous Administered 14C-MNTX

Study Overview
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Brief Summary
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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.

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

Conditions
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Healthy Male Volunteers

Intervention / Treatment
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* Drug: IV methylnaltrexone (MNTX)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Males between 18-45 Subject weight between 70 and 90 kg In good physical health, with no evidence at screening of acute or chronic disease likely to affect the investigation Exclusion Criteria: History or evidence of cardiovascular, gastrointestinal, hepatic, neurological, pulmonary, renal, or other significant chronic condition. Consumption of barbiturates or other inducers or inhibitors of CYP450 isoforms History of or predisposition to erratic or abnormal bowel function.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Non-Randomized
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Arm1<br>MNTX active treatment | Drug: IV methylnaltrexone (MNTX)<br> <br> |

What is the study measuring?
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Primary Outcome Measures

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

Secondary Outcome Measures

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