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Chemistry and Pharmacokinetics of Ethanol Voula Powell

Chemistry and Pharmacokinetics of Ethanol Voula Powell. Characteristics of Ethanol. STRUCTURE: - Two carbon alcohol CH 3 CH 2 OH

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Chemistry and Pharmacokinetics of Ethanol Voula Powell

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  1. Chemistry and Pharmacokinetics of Ethanol Voula Powell

  2. Characteristics of Ethanol • STRUCTURE: - Two carbon alcohol CH3CH2OH • PROPERTIES: -small, polar molecule -soluble in water -specific gravity = 0.789 g/mL -boiling point = 78.5 oC -molecular weight = 46 g

  3. Dosage Determinations • FERMENTATION - concentrations up to 14% • DISTILLATION - increases the concentration • BEVERAGE CONCENTRATIONS: - expressed as weight (w/v - g/100 mL) or volume (v/v - percent) - ETHANOL (%) = PROOF / 2

  4. Amount Consumed Dose (grams) = Volume Conversion Conc. of Specific Ingested X to mLs X Beverage X Gravity (ozs.) (29.6 mL/oz) (mL of ethanol/ (0.789g/ 100 mL) mL)

  5. Blood Concentration Expected BLOOD CONCENTRATION (g/dL) = Dose (grams) Vd (L/kg) X Weight (kg) X 10 (dL/L) Volume of Distribution (Vd): men = 0.67 L/kg women = 0.54 L/kg

  6. Pharmacokinetics of Ethanol • Absorption • Uptake from the gut • Distribution • Transport by the blood to all parts of the body containing water • Elimination • Removal from the body by excretion and by metabolic degradation in the liver

  7. Pharmacokineticsof Ethanol • Fick’s Law • Absorption • Stomach = 20% absorbed • Small Intestine = 80% absorbed • Skin = not absorbed fast enough • Lungs = readily absorbed • Mouth = readily absorbed

  8. Pharmacokinetics of Ethanol • Rate of absorption • Time to peak • rate of ingestion • Decreased rate of absorption - LOWER peak • dilution of ethanol • food in stomach • Increased rate of absorption - HIGHER peak • empty stomach • carbonated beverages

  9. Pharmacokinetics of Ethanol • Distribution • Widmark’s equation • c = A / (p) X (r) • Total Body Water • c=(0.80) X (A) / TBW • c = BAC (g/kg) • p = body weight (kg) • r = reduction factor (ration, Vd) • A = alcohol in body (g) • TBW = total body water (L)

  10. Pharmacokinetics of Ethanol • Elimination Rate • average rate = 0.018 g / dL / hr • range = 0.009 - 0.030 g / dL / hr • Kinetics - Widmark vs. Michaelis-Menten • zero-order • first-order

  11. Pharmacokinetics of Ethanol • Biotransformation - 3 Steps • 1. Ethanol ~~~> Acetaldehyde • 2. Acetaldehyde ~~~> Acetic Acid • 3. Acetic Acid ~~~> Carbon Dioxide and Water

  12. Pharmacokinetics of Ethanol • Metabolism • 1. Alcohol Dehydrogenase • 2. Catalase • 3. MEOS - Cytochrome P450 II E1

  13. Catalase • Abounds in the liver • protection against hydrogen peroxide • Acts as a peroxidase • uses hydrogen peroxide to oxidize other substances • Uses ethanol as a substrate

  14. Microsomal Ethanol-Oxidizing System (MEOS) - Cytochrome P450 II E1 • Primary defense mechanism for detoxifying xenobiotics • Reduces NADPH • High km for ethanol • Microsomal enzymes are inducible • Activated by dietary influences

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