IV. Is nicotine able to readily cross the placenta at pH 7.4? Use equilibrium co

Question

IV. Is nicotine able to readily cross the placenta at pH 7.4? Use equilibrium concepts to explain answer

iii. If the pH of fetal blood is 7.2 (indicating distress) and the pH of maternal blood is 7.4 would you expect a higher, lower, or equal concentration of nicotine in the fetal blood versus the maternal blood, assuming that equilibrium is reached. Explain your answer

Exam II Chem 130, Fall 2016 Page 2 of 11 Question 1 (10 points) products between the fetus and mother. protecting the fetus from harmful substancesh ey are able to e fetus placenta by passive diffusion, meanin membranes that separate the mother e placenta plays a vital role exchanging nutrie The placenta also acts s a barrier, e molecules are able to cross the sion, meaning that they are able to cross the lipid 's blood from that o i. In the st for protonated nicotine are 3.2 and 8.0. Based on youi expected pKa for each of the two amines in nicotine nicotine is given is its fully-protonated form. The two p pka= 3.2 nicotine ii. Draw the predominant structure for nicotine at pH= 7.4(in structure of nicotine that would be able to cross the plac the blood). Draw a enta by passive diffusion. uSiC audi lt,c redominant @ pH 74 explain your answer. ia sfill be char membrane soluble iv) Is nicotine able to readily cross the placenta at pH 7.4? Use equilibrium concepts g,0 and in predominant, This amine No micotine is not verauce one of the amines in the nicotiu orm is charged, and chaed moleces cont pass the mema e me H wod i. f the pH of fetal blood is 7.2 (indicating distress) and the pH of maternal blood the So , would you expect a higher, lower, or equal concentration of nicotine in the fetal blood versus the maternal blood, assuming that equilibrium is reached? Explain re your answer Maternal 7:2 Ht I would expect the tetal bloodl to nave a higher concentraion e there wovld be wore of the protonakd acidic Rm n this

Explanation / Answer

(iii) If there is more deionized form of the drug then it will tend to go across i.e) get into fetal blood
  However fetal blood should have lower pH than maternal blood so that more deionized form
can enter which is opposite in this case and therefore the concentration of nicotine in maternal blood
  will be lower than fetal blood.

(iv) Yes nicotine should be able to readily cross the placenta at PH 7.4 because there will be
a very good percentage of non-ionized form resulting in more ion trapping.

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