Question

TUMS is an antacid and can elevate gastric pH to pH ~3.5. Using clemastine
determine whether the truck driver will get the full antihistamine effect if he takes his
antihistamine at the same time that he takes his TUMS. Provide a rationale for your answer.

Jail TU, ZUZU at 0.JIMIVI Cetirizine Case A long-distance truck driver comes into the pharmacy complaining of seasonal allergies. He asks you to recommend an agent that will act as an antihistamine, but that will not cause drowsiness. He regularly takes TUMS for indigestion due to the bad food he eats while on the road. Cetirizine and clemastine are antihistamine agents. The drugs in the oral dosage form (tablets) can only be absorbed in the non-ionized form. If the drug crosses the blood brain barrier (BBB) in the non-ionized form, the patient will experience drowsiness after taking the drug. OH Cetirizine (Zyrtec) I- N CH2 - CH2-O-CH2-COOH. 2HCI Clemastine fumarate (Tavist) Clemastine pka = 9.55 pka Cetirizine pka1 = 3.6 pka2 = 7.8 2.8 0.066 mg/mL 388.9 Log P Intrinsic solubility Molecular weight 5.8 0.0004 mg/mL 343.9 -

Answer 1

No, the truck driver will not get the full antihistamine effect if he takes his antihistamines at the same time that he takes his TUMS.Antacids can affect how well other medicines work . It is said to take other medicines two to four hours of taking an antacid . It is better to avoid taking antihistamines at the same time with antacids, which may interfere with the way the antihistamine is absorbed, thus making it less effective.