After instillation of cyclopentolate, pupil dilation (
mydriasis) typically lasts up to 24 hours, while paralysis of the
ciliary muscle (
cycloplegia) typically lasts 6-24 hours.[4] During this time, patients may be more light sensitive than normal and may notice close objects blurred (and possibly distant objects blurred, depending on the patient's visual system). Cyclopentolate is often chosen as a milder, shorter-lasting, cycloplegic alternative to
atropine, another cycloplegic agent which lasts much longer.
Tropicamide is an even shorter-lasting cycloplegic than cyclopentolate, but is less reliable for finding latent hyperopia. Cyclopentolate drops act rapidly to dilate the pupil.[5]
The side and adverse effects of cyclopentolate are similar to the side and adverse effects of other
anticholinergic medications. Because of that, extra caution should be taken when prescribing cyclopentolate to patients who are already taking other anticholinergic drugs. A possible ocular (
eye-related) side effect is increase in pressure inside the eye, which is of particular concern when there is a predisposition toward or a presence of
glaucoma. Other ocular side effects can include burning sensations, discomfort with bright light (
photophobia), blurred vision, irritation, inflammation of the eye mucous membranes (
conjunctivitis), inflammation of the cornea of the eye (
keratitis), and other issues. Nonocular (not eye-related) side and adverse effects can include neuropsychiatric symptoms.[6] like subtle
concentration and
memory problems, subtle
decision-making problems,
drowsiness, and more pronounced
disorientation to time and place,
confusion, disturbances of
speech and movement,
hyperactivity,
restlessness, and
seizures. Temporary
psychosis[7] can develop that includes
hallucinations, particularly when higher doses are used in children or older adults[8] on other anticholinergic medications.[9] Patients with
dementia of the Alzheimer's type can experience worsening of their dementia symptoms. Additional side and adverse effects can include skin flushing, skin rashes, gastrointestinal problems, increased heart beat (
tachycardia), increased body temperature (
hyperpyrexia), blood vessel dilation,
urinary retention,
dry mouth and reduced
sweating, and reduced
bronchial secretions. Severe poisoning with cyclopentolate may result in
coma,
paralysis of breathing, and
death. Cyclopentolate derivatives can be used as an antidote for
organophosphate poisoning.[10][11][12][13][14]
Lethality of cyclopentolate has been studied in rodents. The LD50 (the dose at which 50% of animals die from the drug) is approximately 4000 mg/kg in rats and 960 mg/kg in mice. Readily recognizable symptoms of overdose include
tachycardia,
dizziness,
dry mouth,
behavioral disturbances,
uncoordination, and
drowsiness.
Cycloplegia is necessary in cases of suspected latent
hyperopia (or "over-focusing") so that an
ophthalmologist or
optometrist can accurately measure how much a person has to flex their
focusing muscle (
accommodation) in order to see in the distance and up-close. Correction of latent hyperopia in children can often prevent, or sometimes correct, unwanted eye turns (
strabismus), some forms of refractive
amblyopia, and may alleviate eye strain or frontal headaches caused by prolonged near-work. Cycloplegia is also helpful in relieving
accommodative spasm.
History
Cyclopentolate was first synthesized in 1952 as a chemical analogue of
atropine. It was one of several derivatives of an analogue to tropic acid which were tested for pharmacological action "in a search for new and better
antispasmodic agents."[15]
Brand names for cyclopentolate include Cyclogyl, Cylate, Mydrilate, and Pentolair.[16]
^World Health Organization (2021). World Health Organization model list of essential medicines: 22nd list (2021). Geneva: World Health Organization.
hdl:10665/345533. WHO/MHP/HPS/EML/2021.02.
^Bartlett JD, Jaanus SD, eds. (2008). "Chapter 9: Cycloplegics. Table 9-1: Mydriatic and Cycloplegic Properties of Anticholinergic Agents". Clinical Ocular Pharmacology (5th ed.). Saint Louis: Butterworth Heinemann - Elsevier. p. 127.
ISBN978-0-7506-7576-5.
^Derinoz O, Er A (January 2012). "Inability to walk, disequilibrium, incoherent speech, disorientation following the instillation of 1% cyclopentolate eyedrops: case report". Pediatric Emergency Care. 28 (1): 59–60.
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^Barker DB, Solomon DA (September 1990). "The potential for mental status changes associated with systemic absorption of anticholinergic ophthalmic medications: concerns in the elderly". DICP: The Annals of Pharmacotherapy. 24 (9): 847–850.
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^Carpenter WT (October 1967). "Precipitous mental deterioration following cycloplegia with 0.2 percent cyclopentolate HCl". Archives of Ophthalmology. 78 (4): 445–447.
doi:
10.1001/archopht.1967.00980030447006.
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^Bryant SM, Rhee JW, Thompson TM, Lu JJ, Aks SE (2009). "Parenteral ophthalmic tropicamide or cyclopentolate protects rats from lethal organophosphate poisoning". American Journal of Therapeutics. 16 (3): 231–234.
doi:
10.1097/MJT.0b013e318182254b.
PMID19454862.
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^Bauer CR, Trottier MC, Stern L (March 1973). "Systemic cyclopentolate (Cyclogyl) toxicity in the newborn infant". The Journal of Pediatrics. 82 (3): 501–505.
doi:
10.1016/s0022-3476(73)80134-9.
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^Fitzgerald DA, Hanson RM, West C, Martin F, Brown J, Kilham HA (April 1990). "Seizures associated with 1% cyclopentolate eyedrops". Journal of Paediatrics and Child Health. 26 (2): 106–107.
doi:
10.1111/j.1440-1754.1990.tb02399.x.
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^Bhatia SS, Vidyashankar C, Sharma RK, Dubey AK (March 2000). "Systemic toxicity with cyclopentolate eye drops". Indian Pediatrics. 37 (3): 329–331.
PMID10750080.
^Ozgun U, Demet T, Ozge KA, Zafer D, Murat S, Mehmet Y, Nilgun K (May 2014). "Fatal necrotising enterocolitis due to mydriatic eye drops". Journal of the College of Physicians and Surgeons--Pakistan. 24 (Suppl 2): S147–S149.
PMID24906272.
^Treves GR, Testa FC (1952). "Basic Esters and Quaternary Derivatives of β-Hydroxy Acids as Antispasmodics1". Journal of the American Chemical Society. 74 (1): 46–48.
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