Identify the pair of drugs which act as antihistamines.
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It is helpful to memorize the major classes of drugs and a few key examples for each:
- Antihistamines: Cetirizine (Zyrtec), Loratadine (Claritin), Diphenhydramine (Benadryl), Terfenadine (Seldane).
- Tranquilizers: Diazepam (Valium), Alprazolam (Xanax), Barbiturates.
- Analgesics: Aspirin (non-narcotic), Morphine, Codeine (narcotic).
- Antidepressants: Iproniazid, Phenelzine (Nardil).
Let's classify the drugs in each pair.
Antihistamines are drugs that compete with histamine for binding sites on receptors, thereby inhibiting the inflammatory effects of histamine, such as those seen in allergic reactions (e.g., sneezing, itching, runny nose).
(A) Dimetapp, Seldane:
- Dimetapp is a brand name for a combination drug that often contains brompheniramine, which is a classic antihistamine.
- Seldane is the brand name for terfenadine, which is a well-known second-generation antihistamine (though it was largely withdrawn from the market due to side effects).
This pair consists of two antihistamines.
(B) Iproniazid, Nardil:
- Nardil is the brand name for phenelzine.
- Both iproniazid and phenelzine are antidepressants, specifically belonging to the class of monoamine oxidase inhibitors (MAOIs). They are not antihistamines.
(C) Veronal, Valium:
- Veronal is a brand name for barbital, a barbiturate.
- Valium is the brand name for diazepam, a benzodiazepine.
- Both barbiturates and benzodiazepines are tranquilizers or depressants that act on the central nervous system. They are used as sedatives, hypnotics, or anxiolytics. They are not antihistamines.
(D) Heroin, Codeine:
- Both heroin and codeine are opioid analgesics (narcotics). They are used for pain relief and are derived from the opium poppy. They are not antihistamines.
Therefore, the correct pair of drugs that act as antihistamines is Dimetapp and Seldane.
