Page 1142 - Basic _ Clinical Pharmacology ( PDFDrive )

1128 SECTION X Special Topics

Certain ingredients in OTC products should be avoided or increase the blood levels and toxicity of agents such as phenytoin,
used with caution in selected patients because they may exacer- theophylline, and warfarin.
bate existing medical problems or interact with other medica- Overuse or misuse of OTC products may cause significant
tions the patient is taking. The presence of many of the more medical problems. A prime example is rhinitis medicamentosa or
potent OTC ingredients may be unexpectedly hidden in products “rebound rhinitis,” a condition that manifests as nasal congestion
(Table 63–3). Although OTC medications have standardized without rhinorrhea, associated with the regular use of topical
label formatting and content requirements (Figure 63–1), many decongestant nasal sprays for more than 3 days. The improper
consumers do not carefully read or comprehend this informa- and long-term use of some antacids (eg, aluminum hydroxide)
tion. Lack of awareness of the ingredients in OTC products and may cause constipation and even impaction in the elderly, as
the belief by many patients and providers that OTC products well as hypophosphatemia. Long-term laxative use can result in
are ineffective and harmless may cause diagnostic confusion and abdominal cramping and fluid and electrolyte disturbances. A
compromise therapeutic management. For example, innumerable condition known as laxative abuse syndrome is often observed in
OTC products, including analgesics and allergy, cough, and cold women with anorexia nervosa. Insomnia, nervousness, and rest-
preparations, contain sympathomimetics. These agents should be lessness can result from the use of sympathomimetics or caffeine
avoided or used cautiously by patients with type 1 diabetes and present in many OTC products (Table 63–3). The long-term
patients with hypertension, angina, or hyperthyroidism. Aspirin use of analgesics containing caffeine may trigger rebound head-
should not be used in children and adolescents for viral infections aches upon discontinuation. OTC products containing aspirin,
(with or without fever) because of an increased risk of Reye’s syn- other salicylates, acetaminophen, ibuprofen, or naproxen may
drome. Aspirin and other NSAIDs should be avoided by individu- increase the risk of hepatotoxicity and gastrointestinal hemor-
als with active peptic ulcer disease, certain platelet disorders and rhage in individuals who consume three or more alcoholic drinks
patients taking oral anticoagulants. Cimetidine, an H antagonist, daily, and long-term use of these products has been associated
2
is a well-known inhibitor of hepatic drug metabolism and can with interstitial nephritis. Acute ingestion of large amounts of

Drug Facts
Active ingredient (in each tablet) Purpose
Chlorpheniramine maleate 2 mg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Antihistamine
Uses temporarily relieves these symptoms due to hay fever or other upper respiratory allergies:
Sneezing Runny nose Itchy, watery eyes Itchy throat
Warnings
Ask a doctor before use if you have
Glaucoma A breathing problem such as emphysema or chronic bronchitis
Trouble urinating due to an enlarged prostate gland
Ask a doctor or pharmacist before use if you are taking tranquilizers or sedatives
When using this product
You may get drowsy Avoid alcoholic drinks
Alcohol, sedatives, and tranquilizers may increase drowsiness
Be careful when driving a motor vehicle or operating machinery
Excitability may occur, especially in children
If pregnant or breast-feeding, ask a health professional before use.
Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control
Center right away.
Directions
Adults and children 12 years and over Take 2 tablets every 4 to 6 hours;
not more than 12 tablets in 24 hours
Children 6 years to under 12 years Take 1 tablet every 4 to 6 hours;
not more than 6 tablets in 24 hours
Children under 6 years Ask a doctor
Other information store at 20–25°C (68–77°F) Protect from excessive moisture
Inactive ingredients D&C yellow no. 10, lactose, magnesium stearate,
microcrystalline cellulose, pregelatinized starch

FIGURE 63–1 Typical FDA-required labeling for an over-the-counter antihistamine. The label must contain, in the following order: active
ingredient(s), including the amount in each dosage unit; purpose of product (pharmacologic action); use(s) for product (indication); specific
warnings, including when the product should not be used and pregnancy information; when the patient should seek care of a health care
provider; side effects and substances or activities to avoid; dosage instructions (when, how, and how often to take medication); and inactive
ingredients. Additional requirements include, but are not limited to, the following: type size must be large enough to be easily read, >6-point
font type for information in drug facts section; bullets must be solid square or circle 5-point type; and directions in table format for dosage
instructions when presented for three or more age groups or populations. Image from http://www.fda.gov/Drugs/ResourcesForYou/Consumers/
ucm143551.htm