A Textbook of Clinical Pharmacology and Therapeutics

Table 52.6: Common drug-induced problems in patients with contact lenses
Drug Adverse effects Comment
CONTACT LENS WEARERS
As the number of patients who wear contact lenses increases,
an awareness has developed that these patients represent a
special subgroup in whom particular care is needed when
prescribing, as they may develop specific additional problems
related to commonly prescribed drugs. A summary of such
agents is given in Table 52.6.
FURTHER READING
CONTACT LENS WEARERS 429
Oral contraceptives (high oestrogen) Swelling of the corneal surface – poorly
fitting lenses
Visual acuity deterioration
Anxiolytics, hypnotics, first-generation
antihistamines (e.g.
diphenhydramine, etc.)
Reduced rate of blinking Dry eyes and higher risk of infections
Antihistamines, anticholinergics,
phenothazines, diuretics and
tricyclic antidepressants
Reduced lacrimation Dry eyes – irritation and burning
Hydralazine and ephedrine Increased lacrimation
Isotretinoin, aspirin Conjunctival inflammation and irritation
Rifampicin and sulfasalazine Discolour lenses
Case history
A 68-year-old man has hypertension and ischaemic heart
disease. His angina and blood pressure are well controlled
while taking oral therapy with bendroflumethiazide, 2.5 mg
daily, and slow-release diltiazem 120 mg daily. His visual
acuity gradually declines and he is diagnosed as having simple
open-angle glaucoma. His ophthalmologist starts therapy
with pilocarpine 2% eye drops, one drop four times a
day, and carteolol drops, two drops twice a day. A week
after starting to see his ophthalmologist he attends his GP’s
surgery complaining of shortness of breath on exertion,
paroxysmal nocturnal dyspnoea and othopnoea. Clinical
examination reveals a regular pulse of 35 beats per minute,
blood pressure of 158/74 mmHg and signs of mild left ventricular
failure. His ECG shows sinus bradycardia with no evidence
of acute myocardial infarction.
Question
How can you explain this problem and what should your
management be?
Answer
Carteolol is a non-selective β-adrenergic antagonist that can
gain access to the systemic circulation via the nasolachrymal
apparatus thus avoiding heptic first-pass metabolism. It can
thus act (especially in conjunction with a calcium antagonist –
diltiazem in this case) on the cardiac conducting system and
on the working myocardium. Discontinuing the ocular carteolol
should resolve the problem.
Key points
Drugs used to lower intra-ocular pressure
• Systemic administration of:
– osmotic agents (e.g. mannitol);
– acetazolamide (carbonic anhydrase inhibitor).
• Topical administration of:
– pilocarpine (muscarinic agonist);
– timolol (β-adrenoceptor antagonist);
– dorzolamide (carbonic anhydrase inhibitor);
– latanoprost (PGF2α analogue);
– brimonidine (α2-agonist). Ghate D, Edelhauser HF. Ocular drug delivery. Expert Opinion on Drug
Delivery 2006; 3: 275–87.
Marquis RE, Whitson JT. Management of glaucoma: focus on pharmacological
therapy. Drugs and Aging 2005; 22: 1–21.