Intravenous Ethanol Infusions Can Mimic the Time Course of Breath Alcohol Concentrations Following Oral Alcohol Administration in Healthy Volunteers

Laboratory of Clinical and Translational Studies, National Institute on Alcohol Abuse and Alcoholism, 10 Center Drive, Bethesda, MD 20892, USA.
Alcoholism Clinical and Experimental Research (Impact Factor: 3.21). 04/2009; 33(5):938-44. DOI: 10.1111/j.1530-0277.2009.00906.x
Source: PubMed


Our previous studies have used intravenous (IV) clamping methods to demonstrate that family history positive (FHP) subjects exhibit a greater initial response to alcohol than family history negative (FHN) subjects. These results differ from other studies of family history of alcoholism (FHA) influences, most of which have used an oral alcohol challenge, suggesting that the route of administration may influence both the response to alcohol and FHA-related differences in response. To examine this possibility, one approach would be to directly compare responses following oral and IV alcohol administration in the same subjects. There is, however, a 3- to 4-fold variance, between- and within-subjects, in the breath alcohol concentrations (BrACs) following oral alcohol administration. Thus, our objective was to characterize the between-subject variability in the time course of BrACs following oral alcohol administration in healthy volunteers and to develop an IV infusion method to mimic the BrAC-time course attained following oral alcohol in the same subject.
This was a 2-session study in young adult, healthy, nondependent drinkers. In the first session, subjects ingested an oral dose of alcohol, based on total body water, to achieve a target peak BrAC of 80 mg%. In the second session, subjects received an IV infusion of ethanol designed to achieve the same BrAC time course as that achieved in the first session. The individualized infusion-rate profile was precomputed using a physiologically-based pharmacokinetic (PBPK) model for alcohol with model parameters adjusted to the individual's physiology. The peak BrACs (C(max)), times of peak BrAC (T(max)), and the areas under the BrAC vs. time curve (AUC) were compared between sessions to assess how closely the BrAC exposure during the IV infusion session mimicked the exposure following oral alcohol.
The time course of BrACs following oral alcohol administration showed a high degree of between-subject variability. Mean C(max), T(max), and AUC did not differ by gender, indicating that calculation of oral doses based on total body water results in comparable BrAC-time courses, on average, for females and males. The IV infusion driven BrAC-time profiles demonstrated good fidelity to the BrAC-time curves resulting from oral alcohol: the mean %difference in C(max) and AUC were both 11%, while the mean %difference for T(max) was 27%. This degree of variability is less than half that seen across individuals following oral alcohol administration, which was substantial [coefficient of variation (%CV) ranging from 22 to 52%].
Despite the use of standardized doses and controlled experimental conditions, there was substantial between-subject variability in the BrAC time course following oral administration of alcohol. The PBPK-model-based infusion method can mimic the BrACs attained with oral alcohol for individual subjects. This method provides a platform to evaluate effects attributable to the route of administration on the response to alcohol, as well as the influence of determinants such as family history of alcoholism on the alcohol response.

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    • "Additionally, it is currently unclear whether subjective response reliably differs between oral and intravenous alcohol administration, as only a single study has systematically examined differences in alcohol responses between these 2 methods (Ray et al., 2007) and reported greater levels of intoxication, but lower alcohol craving, from intravenous alcohol (possibly due to the absence of alcohol cues). However, recent developments in computerized intravenous alcohol administration paradigms allow for the mimicking of oral BACs (Ramchandani et al., 2009), thus permitting rigorous comparison of subjective response variables across these routes of administration while controlling for BAC-related confounds. It is also worth noting that comparison of drinking groups with different alcohol use histories requires careful consideration of tolerance effects. "
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    • "The difficulty arises because the time course of BrAC(t) following oral alcohol administration is subject to substantial uncontrollable variation in absorption, and to lesser, but still significant, differences in the distribution and elimination kinetics among subjects. An oral dose, even when formulated and delivered with procedures attempting to minimize controllable sources of variation produces a 2–3 fold range of ascending limb slopes, peak BrACs achieved, and latencies to peak BrAC (Ramchandani et al., 2009). If BrAC(t) itself cannot be controlled effectively by oral dosing, prescribing the slope of BrAC(t) for experimental purposes would be even more difficult using ingested alcohol. "
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