Topical anesthetic

Agent that numbs a body surface

A topical anesthetic is a local anesthetic that is used to numb the surface of a body part. They can be used to numb any area of the skin as well as the front of the eyeball, the inside of the nose, ear or throat, the anus and the genital area.[1] Topical anesthetics are available in creams, ointments, aerosols, sprays, lotions, and jellies. Examples include benzocaine, butamben, dibucaine, lidocaine, oxybuprocaine, pramoxine, proxymetacaine (proparacaine), and tetracaine (also named amethocaine).[citation needed]

## Usage

[edit]

Topical anesthetics are used to relieve pain and itching caused by conditions such as sunburn or other minor burns, insect bites or stings, poison ivy, poison oak, poison sumac, and minor cuts and scratches.[2]

Topical anesthetics are used in ophthalmology and optometry to numb the surface of the eye (the outermost layers of the cornea and conjunctiva) to:

* Perform a contact/applanation tonometry.
* Perform a Schirmer's test (The Schirmer's test is sometimes used with a topical eye anesthetic, sometimes without. The use of a topical anesthetic might impede the reliability of the Schirmer's test and should be avoided if possible.).
* Remove small foreign objects from the uppermost layer of the cornea or conjunctiva. The deeper and the larger a foreign object which should be removed lies within the cornea and the more complicated it is to remove it, the more drops of topical anesthetic are necessary prior to the removal of the foreign object to numb the surface of the eye with enough intensity and duration.

In dentistry, topical anesthetics are used to numb oral tissue before administering a dental local anesthetic due to the entry of the needle into the soft tissues of the oral cavity.[3] Dental anesthetic gels are sometimes flavored to make usage more tolerable for patients, especially in pediatric dentistry.[4]

Some topical anesthetics (e.g. oxybuprocaine) are also used in otolaryngology.

Topical anesthetics are sometimes abused for temporary relief of premature ejaculation when applied to the glans (head) of the penis.[citation needed] Benzocaine or lidocaine are typically used for this purpose as they are available as over-the-counter drugs.

## Abuse when used for ocular pain relief

[edit]

When used excessively, topical anesthetics can cause severe and irreversible damage to corneal tissues[5][6][7][8][9] and even loss of the eye.[10] The abuse of topical anesthetics often creates challenges for correct diagnosis in that it is a relatively uncommon entity that may initially present as a chronic keratitis, masquerading as acanthamoeba keratitis or other infectious keratitis.[5][6][8][10][11] When a keratitis is unresponsive to treatment and associated with strong ocular pain, topical anesthetic abuse should be considered,[8] and a history of psychiatric disorders and other substance abuse have been implicated as important factors in the diagnosis.[5][10][11] Because of the potential for abuse, clinicians have been warned about the possibility of theft and advised against prescribing topical anesthetics for therapeutic purposes.[6][10]

Some patients who have eye pain, which is often considerably strong neuropathic pain caused by the irritation of the nerves within the cornea and/or conjunctiva, try to illegally obtain oxybuprocaine or other eye anesthetics (for example by stealing them at their ophthalmologist or optometrist, by forging medical prescriptions or by trying to order it via an online pharmacy) and use the substance to numb their eye pain, often ending up with irreversible corneal damage or even destruction (which is a vicious cycle and causes more pain). Often, such patients finally require corneal transplantation.

In case of prolonged or chronic eye pain, especially neuropathic eye pain, it is highly advisable to use centrally acting substances like anticonvulsants (pregabalin, gabapentin and in more serious cases carbamazepine) or antidepressants (for example SSRIs or the tricyclic antidepressant amitriptyline). Even very small amounts of an anticonvulsant and/or an antidepressant can almost completely stop eye pain and does not damage the eye at all.[citation needed]

## See also

[edit]

* Local anesthesia
* Topical

## Notes

[edit]

1. ^ "Healthopedia.com". Archived from the original on 2005-11-26. Retrieved 2006-03-30.
2. ^ DrLinhart.com
3. ^ Local Anesthesia for the Dental Hygienist, Logothetis, Elsevier, 2012
4. ^ Ferrazzano, Gianmaria Fabrizio; Di Fabio, Giuseppe; Gatto, Roberto; Caruso, Sara; Botticelli, Gianluca; Caruso, Silvia (2023-02-24). "Effectiveness and Tolerability of a New Formulation of a Topical Anesthetic in Reduction of Pain and Parents' Satisfaction in Pediatric Dentistry". Children. 10 (3): 444. doi:10.3390/children10030444. ISSN 2227-9067. PMC 10047767. PMID 36980002.
5. ^ a b c Pharmakakis NM, Katsimpris JM, Melachrinou MP, Koliopoulos JX (2002). "Corneal complications following abuse of topical anesthetics". Eur J Ophthalmol. 12 (5): 373–8\. doi:10.1177/112067210201200505. PMID 12474918. S2CID 196168539.
6. ^ a b c Varga JH, Rubinfeld RS, Wolf TC, et al. (July 1997). "Topical anesthetic abuse ring keratitis: report of four cases". Cornea. 16 (4): 424–9\. doi:10.1097/00003226-199707000-00009. PMID 9220240.
7. ^ Chern KC, Meisler DM, Wilhelmus KR, Jones DB, Stern GA, Lowder CY (January 1996). "Corneal anesthetic abuse and Candida keratitis". Ophthalmology. 103 (1): 37–40\. doi:10.1016/s0161-6420(96)30735-5. PMID 8628558.
8. ^ a b c Ardjomand N, Faschinger C, Haller-Schober EM, Scarpatetti M, Faulborn J (November 2002). "[A clinico-pathological case report of necrotizing ulcerating keratopathy due to topical anaesthetic abuse]". Ophthalmologe (in German). 99 (11): 872–5\. doi:10.1007/s00347-002-0623-z. PMID 12430041. S2CID 20724555.
9. ^ Chen HT, Chen KH, Hsu WM (July 2004). "Toxic keratopathy associated with abuse of low-dose anesthetic: a case report". Cornea. 23 (5): 527–9\. doi:10.1097/01.ico.0000114127.63670.06. PMID 15220742. S2CID 1836290.
10. ^ a b c d Rosenwasser GO, Holland S, Pflugfelder SC, et al. (August 1990). "Topical anesthetic abuse". Ophthalmology. 97 (8): 967–72\. doi:10.1016/s0161-6420(90)32458-2. PMID 2402423.
11. ^ a b Sun MH, Huang SC, Chen TL, Tsai RJ (June 2000). "Topical ocular anesthetic abuse: case report". Chang Gung Med J. 23 (6): 377–81\. PMID 10958042.

## External links

[edit]

Wikiversity has learning resources about Topical anesthetic

* Principles of Office Anesthesia: Part II. Topical Anesthesia

* v
* t
* e

Anesthesia and anesthesiology

Types|

* General
* Sedation
* Procedural sedation and analgesia
* Twilight anesthesia
* Local
* Continuous wound infiltration
* Topical
* Neuraxial blockade
* Combined spinal and epidural anaesthesia
* Epidural anesthesia
* Spinal anaesthesia
* Nerve block
* Brachial plexus block
* Fascia iliaca block
* Femoral nerve block
* Inferior alveolar nerve block
* Intercostal nerve block
* Interpleural block
* Intravenous regional anesthesia
* Occipital nerve block
* Paracervical block
* Pudendal nerve block
* Retrobulbar block
* Sciatic nerve block
* Transverse abdominis plane block
* Total intravenous anaesthesia

Pharmacologic agents|

* Anticholinergics
* Antiemetics
* Butyrophenones
* Benzodiazepines
* General anesthetics
* Inhalational anesthetics
* Local anesthetics
* Neuromuscular-blocking drugs
* Opioids
* Sedatives

Techniques|

* Airway management
* Anesthesia provision in the US
* Bronchoscopy
* Dogliotti's principle
* Intravenous therapy
* Laryngoscopy
* Tracheal intubation
* Rapid sequence induction

Scientific principles|

* Blood–gas partition coefficient
* Concentration effect
* Fink effect
* Minimum alveolar concentration
* Second gas effect

Measurements|

* ASA physical status classification system
* Baricity
* Bispectral index
* Body mass index
* Capnography
* Entropy monitoring
* Fick principle
* Goldman index
* Guedel's classification
* Intraoperative neurophysiological monitoring
* Mallampati score
* Neuromuscular monitoring
* Pain scale
* Thyromental distance

Instruments|

* Anaesthetic machine
* Anesthetic vaporizer
* Arterial catheter
* Bronchial blocker
* Double-lumen endobronchial tube
* Gas cylinder
* Laryngeal mask airway
* Laryngeal tube
* Magill forceps
* Relative analgesia machine
* Tracheal tube

Complications|

* Allergic reactions
* Anesthesia awareness
* Drug-induced amnesia
* Effects of early-life exposures to anesthesia on the brain
* Emergence delirium
* Local anesthetic toxicity
* Malignant hyperthermia
* Perioperative mortality
* Postanesthetic shivering
* Postoperative nausea and vomiting
* Postoperative residual curarization

Subspecialties|

* Cardiothoracic
* Critical emergency medicine
* Geriatric
* Intensive care medicine
* Obstetric
* Oral sedation dentistry
* Pain medicine

Professions|

* Anesthesiologist
* Anesthesiologist assistant
* Nurse anesthetist
* Operating department practitioners
* Certified anesthesia technician
* Certified anesthesia technologist
* Anaesthetic technician
* Physicians' assistant (anaesthesia)

History|

* ACE mixture
* Helsinki Declaration for Patient Safety in Anaesthesiology
* History of general anesthesia
* History of neuraxial anesthesia
* History of tracheal intubation

Organizations|

* American Association of Nurse Anesthetists
* American Society of Anesthesia Technologists & Technicians
* American Society of Anesthesiologists
* Anaesthesia Trauma and Critical Care
* Association of Anaesthetists of Great Britain and Ireland
* Royal College of Anaesthetists
* Association of Veterinary Anaesthetists
* Australian and New Zealand College of Anaesthetists
* Australian Society of Anaesthetists
* International Anesthesia Research Society
* European Society of Anaesthesiology and Intensive Care

* Category
* Outline

* Principles of Office Anesthesia: Part II. Topical Anesthesia

*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template