A three-year-old child is brought to the emergency department having just ingested a large overdose of an antihistaminic drug. This drug is a weak base capable of entering most tissues including the brain. On physical examination the heart rate is 100/minute, blood pressure is 110/60 mm Hg and the respiratory rate is 20/minute. In this case of poisoning:
- Ionization of acidic drugs is increased in alkaline urine and vice versa. Ionized drugs cannot cross the plasma membrane easily. So is not reabsorbed into the blood from the tubules. Hence, enhanced excretion of the acidic drug through alkaline urine or basic drug through acidic urine. 
- A basic drug would be ionized more in acidic pH. Plasma is alkaline.
- The un-ionized form is absorbed easily. So absorption will be more in an alkaline environment in the intestine.
Urinary excretion would be accelerated by administration of NH4Cl, an acidifying agent
Urinary excretion would be accelerated by administration of NaHCO3, an alkalinizing agent
More of the drug would be ionized at blood pH than at stomach pH
Absorption of the drug would be faster from the stomach than from the small intestine.