The aim of the study is to investigate the effect of antidepressant paroxetine, on the plasma levels of timolol and its main metabolites after topical application of ophthalmic timolol products.

This will be a phase I, randomised, 4-phase cross-over study in healthy volunteers. Healthy male volunteers aged 18 - 40 years will be enrolled.

Placebo or paroxetine will be given for three days after which 1 drop of timolol product will be administered once in both eyes.

The duration of the paroxetine or placebo treatment period will be 3 days. There will be four different treatment periods. A washout between the study periods will be at least 4 weeks.

Inclusion Criteria:

• male
• 18 - 40 years of age
• be in good general health
• be willing to follow instructions
• provide a written informed consent
• have a BMI of 18.5 - 26
• have systolic blood pressure at least 105 mmHg
• have haemoglobin at least 135 g/l.

Exclusion Criteria:

• known hypersensitivity to timolol, paroxetine or any component of the study medications
• any contraindications to timolol treatment including asthma and obstructive lung disease
• any contraindications to paroxetine treatment
• have heart rate 50/min or less in rest
• any regular medication
• allergy requiring antihistamine or ocular or nasal treatment
• clinically significant abnormalities (from normal limits) in laboratory values: basic blood count, creatinine, ALAT, AFOS, gamma-GT, K, Na
• clinically significant EKG abnormalities assessed by the investigator
• blood donation within the last 60 days (the required time period between two donations for men given by RedCross Finland).
• participation in another clinical trial involving an investigational drug/device, or participation in such trial within the last 60 days