3.4: Tetracyclines

Tetracyclines are broad-spectrum antibiotics that are bacteriostatic, subsequently inhibiting bacterial growth.

Indications: Tetracycline medications are useful for the treatment of many gram-positive and gram-negative infectious processes, yet are limited due to the significance of side effects experienced by many patients.

Mechanism of Action: Tetracyclines work by penetrating the bacterial cell wall and binding to the 30S ribosome, inhibiting the protein synthesis required to make the cellular wall.^[1]

Special Administration Considerations: Significant side effects of tetracycline drug therapy include photosensitivity, discoloration of developing teeth and enamel hypoplasia, and renal and liver impairment.^[2] Tetracyclines are contraindicated in pregnancy and for children ages 8 and under. Small amounts may be excreted in breast milk.

Patient Teaching & Education: Patients should be instructed to avoid direct sunlight exposure and wear sunscreen to prevent skin sensitivities. Additionally, it is important for patients to be educated regarding potential impaired absorption of tetracycline with the use of dairy products. Patients who are on oral contraceptives should be educated that tetracyclines may impede the effectiveness of the oral contraceptive and an alternative measure of birth control should be utilized while on the antibiotic. Female patients must be aware to immediately stop tetracycline if they become pregnant. Expired tetracycline should be immediately disposed of as it can become toxic.^[3]

Now let’s take a closer look at the medication grid for tetracycline in Table 3.13.^[4]

Table 3:13 Tetracycline Medication Grid

Class/Subclass	Prototype/Generic	Administration Considerations	Therapeutic Effects	Side/Adverse Effects
Tetracyclines	tetracycline	Check allergies Alert: Check expiration date. Using outdated or deteriorated drug has been linked to severe reversible nephrotoxicity (Fanconi syndrome) Effectiveness is reduced when drug is given with milk or other dairy products, antacids, or iron products For best drug absorption, give drug with a full glass of water on an empty stomach at least 1 hour before or 2 hours after meals Give drug at least 1 hour before bedtime to prevent esophageal irritation or ulceration Use caution with renal or hepatic impairment Avoid using in children younger than age 8 because drug may cause permanent discoloration of teeth, enamel defects, and bone growth retardation Avoid in pregnancy due to toxic effects on the developing fetus (often related to retardation of skeletal development and teeth)	Monitor for systemic signs of infection: -WBCs – Fever Monitor actual site of infection	Gastrointestinal symptoms C-diff Photosensitivity Oral candidiasis Permanent teeth discoloration if given to patients < 8 y.o. Intracranial hypertension: Monitor for headache, blurred vision, diplopia, and vision loss Decreased effectiveness of oral contraceptives

Critical Thinking Activity 3.13a

Using the above grid information, consider the following clinical scenario question:

The nurse is providing medication teaching to a parent of a six-year-old child with strep throat in a clinic setting. Due to multiple drug allergies, tetracycline was prescribed by a doctor who is new to the clinic. What is the nurse’s best response and why?

Note: Answers to the Critical Thinking activities can be found in the “Answer Key” sections at the end of the book.

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1. This work is a derivative of Microbiology by OpenStax licensed under CC BY 4.0. Access for free at https://openstax.org/books/microbiology/pages/1-introduction↵
2. This work is a derivative of Microbiology by OpenStax licensed under CC BY 4.0. Access for free at https://openstax.org/books/microbiology/pages/1-introduction↵
3. uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral↵
4. Daily Med, dailymed.nlm.nih.gov/dailymed/index.cfm, used for hyperlinked medications in this module. Retrieved June 27, 2019 ↵