1. International Health Policy Program -Thailand Thaksaphon Thamarangsi BAC and Widmark’s Formula

2. International Health Policy Program -Thailand 2 Basic knowledge (1) Alcohol: Ethanol vs Methanol Metabolism of alcohol Effect of alcoholic beverages on Central Nervous System – Intoxication ---- Acetaldehyde – Dehydration – Hypoglycemia – Transient Vitamin B deficiency Blood alcohol concentration (BAC) Blood-Breath-Urine

3. International Health Policy Program -Thailand 3 What determines BAC? Let’s discuss

4. International Health Policy Program -Thailand 4 Basic knowledge (2) Unit of wt 1 kg =1000 gm, 1 gm= 1000 mg Unit of Volume 1 L = 10 dl =1000 ml Unit of BAC – weight / volume: mg/dl = 1000 * g/dl = 1000* g%/ml – Wt/wt: mg/ 100 mg of blood Beverage degree: what does it mean 5% alcohol content? D=M/V or M=V x D Density of ethanol = 0.79 or 0.8 Concentration? (Practice 1: 0.1 kg of NaCl in 2 Liters of H2O, Conc in mg/dl=?) Answer= 5000 mg/dl

5. International Health Policy Program -Thailand 5 Practice 2-3 Practice 2: how many grams of ethanol in 1 bottle (0.75 L=75 CL=750 ml) of Black Label (42%) Answer (248.9 gm) Practice 3: Average Thai male youth drink 118 gm per drinking day, calculate this amount in terms of how many bottle (0.63 L) of Chang beer (6.4%). Answer (3.7 bottle)

6. International Health Policy Program -Thailand 6 Basic knowledge(3) Male vs Female Does alcohol equally distribute through our body? Is alcohol eliminated (from our body) at constant rate ?

7. International Health Policy Program -Thailand 7 Adapted from Wilkinson et al., Journal of Pharmacokinetics and Biopharmaceutics5(3):207- 224, 1977

8. International Health Policy Program -Thailand 8 Eric Widmark N = f(W, r,Ct,β, t, z) N = amount consumed W = body weight r = the volume of distribution (a constant) Ct = blood alcohol concentration (BAC) β = the alcohol elimination rate t = time since the first drink z = the fluid ounces of alcohol per drink

9. International Health Policy Program -Thailand 9 N = Wr(Ct + βt) 0.8z N = the number of drinks consumed W = body weight in ounces r = volume of distribution (a constant relating the distribution of water in the body in L/Kg) Ct = the blood alcohol concentration (BAC) in Kg/L β = the alcohol elimination rate in Kg/L/hr t = time since the first drink in hours z = the fluid ounces of alcohol per drink 0.8 = the density of ethanol (0.8 oz. per fluid ounce)

10. International Health Policy Program -Thailand 10 Widmark’s formula BAC = fully absorbed conc. - eliminated conc. Fully absorbed = unit = mg/dl = wt of ethanol consumed / (volume of body that can hold alcohol) = R= 0.68 for male, 0.55 for female Blood density =1.055 = 0.79 x Volume of ethanol Body weight x R Blood Density [] 0.79 x Volume of ethanol Body weight x 0.68 (0.55) 1.055 []

11. International Health Policy Program -Thailand 11 Unit Unit Unit Fully absorbed = unit = mg/dl 0.79 x Volume of ethanol (ml) Body weight (kg) x R 1.055 [ ] Then x 100 to be in mg/dl 0.79 x Volume of ethanol (ml) Body weight (kg) x R 1.055 [ ] = gram / L =1000 mg / 10 dl =100 mg/dl

12. International Health Policy Program -Thailand 12 Practice 4-5 Practice#4: A young lady (45 kg) rapidly consumed 3 bottles (630 ml) of Heineken beer (5%), what us her maximum BAC? Answer 318.22 mg/dl Practice#5: A man of 70 kg consumed 325 ml of 40% distilled spirits Answer 227.6 mg/dl

13. International Health Policy Program -Thailand 13 Useful formula Elimination rate = Time x Elimination rate (Widmark’s Beta) Beta = 0.017 % (0.010-0.024) In another term = 15 - 17 mg/dl Practice 6: how many hour would the subject in Practice 4, 5 eliminate all alcohol? Answer (18.7 hours, 13.4 hours)

14. International Health Policy Program -Thailand 14 Useful formula Elimination rate = Time x Elimination rate (Widmark’s Beta) BAC = 0.79 x Volume of ethanol Body weight x R Blood Density [] - Hour x Elim rate

15. International Health Policy Program -Thailand 15 Practice 8 An RTA injured man (65 kg) came to ER, time of accident 23.30, Breath test at 24.00 showed BAC =40.06 what is the BAC at the time of crash? Answer 48.56 mg/dl

16. International Health Policy Program -Thailand 16 Practice 9 An RTA injured man (65 kg) came to ER at 24.00, time of accident 23.30, reporting drinking of 2 cans (335 ml) of Leo beer (6%) between 21.00-23.00 (regularly & equally consumed over consumption period), what is the BAC at the time of crash? Answer 48.56 mg/dl