Thus they are not suitable for hypertensive patients. Pseudoephedrine has been shown to have little effect on normotensive patients while ephedrine has the most marked pressor activity. Theophylline is a bronchodilator which is included in some OTC preparations. It causes smooth muscle relaxation but its mechanism of action is not fully understood. The concentration employed in OTC cough remedies may be sub-therapeutic for adults but because of the low dose they are safe.
Inhalations can help productive coughs by reducing phlegm viscosity.
Nasal problems Both congestion and a runny nose respond to the same therapeutic agents. In many cases, the same class of agent may be for either topical or systemic administration. Sympathomimetics Includes all those listed above plus phenylephrine. All the comments above apply to their use as systemic nasal decongestants. Preparations for local administration may also contain the metazolines.