Bimatoprost + Timolol

Ophthalmic
Ocular hypertension, Open-angle glaucoma

Reactive airway disease including bronchial asthma or history of bronchial asthma, severe COPD; sinus bradycardia, sick sinus syndrome, SA block, 2nd or 3rd degree AV block, not controlled w/ pacemaker; overt cardiac failure, cardiogenic shock.

Patient w/ CV diseases (e.g. CHD, Prinzmetal’s angina, cardiac failure), hypotension therapy w/ β-blockers; severe peripheral circulatory disturbance/disorders (i.e. severe forms of Raynaud's disease/syndrome); mild to moderate COPD; patient subject to spontaneous hypoglycaemia or to patient w/ labile diabetes; corneal diseases. Hepatic or renal impairment. Pregnancy and lactation.

Headache, dizziness; conjunctival hyperaemia, superficial punctuate keratitis, corneal erosion, burning sensation, eye pruritus, dryness, pain, discharge, and irritation, stinging sensation in the eye, foreign body sensation in the eye, foreign body sensation, eyelid erythema, pruritus, and oedema, photophobia, visual disturbance, visual acuity worsened, blepharitis, epiphora, growth of eyelashes; rhinitis, blepharal pigmentation, hirsutism, periocular skin hyperpigmentation.

This drug may cause transient blurred vision, if affected, do not drive or operate machinery.

Additive effects resulting in hypotension and/or marked bradycardia w/ oral Ca channel blockers, guanethidine, β-blockers, parasympathomimetics, anti-arrhythmics, digitalis glycosides. Potentiation of systemic β-blockade (e.g. decreased heart rate, depression) w/ CYP2D6 inhibitors (e.g. quinidine, fluoxetine, paroxetine). Combination w/ epinephrine may cause mydriasis.

Description:
Mechanism of Action: Bimatoprost is a synthetic prostamide structurally related to prostaglandin F_2α which reduces intraocular pressure (IOP) by increasing aqueous humour outflow through the trabecular meshwork and enhancing uveoscleral outflow. Timolol is a β₁ and β₂ non-selective adrenergic receptor blocking agent which lowers IOP by reducing aqueous humour formation. Bimatoprost and timolol decrease elevated IOP by complementary mechanisms of action and the combined effect results in additional IOP reduction compared to either compd administered alone.
Pharmacokinetics:
Absorption: Bimatoprost: Small amounts are absorbed (ophth). Time to peak plasma concentration: W/in 10 min. Timolol: Time to peak plasma concentration: Approx 1-2 hr.
Distribution: Bimatoprost: Moderately distributed into body tissues. Volume of distribution: 0.67 L/kg. Plasma protein binding: Approx 88%.
Metabolism: Bimatoprost: Undergoes oxidation, de-ethylation and glucuronidation. Timolol: Undergoes partial hepatic metabolism.
Excretion: Bimatoprost: Mainly via urine (up to 67%); faeces (approx 25%). Elimination half-life: 45 min. Timolol: Via urine as unchanged drug and metabolites. Plasma half-life: Approx 4-6 hr.

Source: National Center for Biotechnology Information. PubChem Database. Bimatoprost, CID=5311027, https://pubchem.ncbi.nlm.nih.gov/compound/Bimatoprost (accessed on Jan. 21, 2020)

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 33624, Timolol. https://pubchem.ncbi.nlm.nih.gov/compound/Timolol. Accessed Feb. 23, 2023.

Antiglaucoma Preparations

Buckingham R (ed). Bimatoprost. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/03/2016.

Buckingham R (ed). Timolol Maleate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/03/2016.

Joint Formulary Committee. Bimatoprost with Timolol. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/03/2016.