Tetracaine is an ester-type local anesthetic that stabilizes the neuronal membrane by preferentially binding to sodium channels, thereby preventing sodium from entering the cell. Without the influx of sodium ions, the initiation and conduction of signals are blocked. It is important to note that ester-type local anesthetics, in general, metabolize into Para-aminobenzoic acid (PABA), which antagonize the effects of sulfonamides.1 Tetracaine is fast-acting and has a long duration, and can be used as a spinal anesthetic or nerve block delivered via injection, or as a topical solution for short ophthalmic procedures.
For more information, including a MSDS sheet, please see PNA’sTetracaine page.
Injected anesthetic: Injected tetracaine is used as a nerve block or as a spinal anesthetic for procedures that are 2-3+ hours long.
Topical anesthetic: Topical tetracaine is used to numb the eye for procedures such as tonometry, gonioscopy, or removal of foreign bodies or sutures.2
Other Uses: Tetracaine in combination with other drugs may be used as an anesthetic for surgical, endoscopic, or other procedures in the ear, nose, mouth, pharynx, larynx, trachea, bronchi, and esophagus. The drug is sometimes also used in the case of vaginal or rectal procedures.3
Side Effects and Drug Interactions
Common side effects in patients taking tetracaine include4:
Anxiety, nervousness, or excitement
Nausea or vomiting
Patients who suffer from severity of these common side effects should contact their pharmacist or physician right away. Patients who experience an allergic reaction (hives, trouble breathing, swelling of the face, lips, tongue, or throat), lightheadedness, fainting, tremors, severe drowsiness, weak breathing, severe headache, stiff neck, sensitivity to light, or numbness, tingling, burning pain, or severe shooting pains should contact their physician right away.
Patients who are allergic to tetracaine or similar numbing compounds (such as lidocaine, benzocaine, or prilocaine) should not take this drug. Patients taking amyl nitrite, sodium nitrite, sodium thiosulfate, or general sulfa drugs should inform their physician before starting this medication. Patients who have or who have had high blood pressure, heart disease, heart arrhythmia, infection at the the site where the drug is applied topically or where the injection is given, hereditary angioedema, or a history of allergic reactions should also inform their physician before taking this drug. This drug has not been studied in pregnant or breastfeeding patients.
Bupivacaine is contraindicated against tetracaine/lidocaine combinations. Side effects other than the ones listed here may be seen with combinations of tetracaine and lidocaine or other drugs. Fatal overdose is possible with this or any other numbing medication. Signs of overdose include uneven heartbeats, seizures, coma, slowed breathing, or respiratory failure.5
Latest News and Research
Although tetracaine shows high efficacy as a short-term anesthetic, some conditions that are not suitable for acute treatment may still benefit from tetracaine. A treatment using a heated lidocaine/tetracaine patch is currently being evaluated for shoulder impingement syndrome. The treatment is being evaluated against subacromial corticosteroid injections, which are currently part of a conservative line of treatment that begins with nonsteroidal anti-inflammatory drugs and physical therapy.6 In a study of 60 patients, the heated lidocaine/tetracaine patch showed similar efficacy to the steroid injections, but without the invasive aspect of treatment.
A lidocaine/tetracaine patch may also provide much needed relief prior to arterial catheterization.7 The catheterization procedure is both painful and stressful—the transdermal patch offers patients analgesic relief without adding another injection to the procedure. Initial results show that the patch offers at least as much efficacy as an injected analgesic.
“Tetracaine Side Effects,” January 4, 2016, http://www.drugs.com/sfx/tetracaine-side-effects.html ↩
“What Is Tetracaine Topical?” 2016, http://www.everydayhealth.com/drugs/tetracaine-topical ↩
“A randomized clinical study of the heated lidocaine/tetracaine patch versus subacromial corticosteroid injection for the treatment of pain associated with shoulder impingement syndrome, July 2014, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4266383/ ↩
” Lidocaine/tetracaine patch (Rapydan) for topical anaesthesia before arterial access: a double-blind, randomized trial,” July 24, 2012, http://bja.oxfordjournals.org/content/early/2012/07/24/bja.aes254.short ↩