Actions of Timolina in details
Timolina (Timolina maleate, MSD) reduces elevated and normal intraocular pressure whether or not associated with glaucoma. Elevated intraocular pressure is a major risk factor in the pathogenesis of glaucomatous visual field loss. The higher the level of intraocular pressure, the greater the likelihood of glaucomatous visual field loss and optic nerve damage.
Onset of action of Timolina is usually rapid, occurring approximately 20 min after topical application to the eye. Maximum reduction of intraocular pressure occurs in 1-2 hrs. Significant lowering of intraocular pressure has been maintained for as long as 24 hrs with 0.25% or 0.5% Timolina ophthalmic solution. This extended duration of action permits control of intraocular pressure over the usual sleeping hours. Repeated observations over a period of 3 years indicate that the intraocular pressure-lowering effect of Timolina is well maintained.
Timolina maleate is a nonselective β-adrenergic receptor-blocking agent that does not have significant intrinsic sympathomimetic, direct myocardial depressant or local anesthetic (membrane-stabilizing) activity.
The precise mechanism of action of Timolina in lowering intraocular pressure is not clearly established at this time, although a fluorescein study and tonography studies indicate that the predominant action may be related to reduce aqueous formation. However, in some studies a slight increase in outflow facility was also observed.
Unlike miotics, Timolina reduces intraocular pressure with little or no effect on accommodation or pupil size. Thus, changes in visual acuity due to increased accommodation are uncommon, and dim or blurred vision and nightblindness produced by miotics are not evident. In addition, in patients with cataracts, the inability to see around lenticular opacities when the pupil is constricted by miotics is avoided. When changing patients from miotics to Timolina, a refraction might be necessary when these effects of the miotic have passed.
In clinical studies, Timolina was generally effective in more patients and produced fewer and less severe side effects than either pilocarpine or epinephrine.
As with the use of other antiglaucoma drugs, diminished responsiveness to Timolina after prolonged therapy has been reported in some patients. However, in clinical studies in which 164 patients have been followed for at least 3 years, no significant difference in mean intraocular pressure has been observed after initial stabilization.
Timolina has also been used in patients with glaucoma wearing conventional hard contact lenses, and has generally been well tolerated. Timolina has not been studied in patients wearing lenses made with materials other than polymethylmethacrylate.
How should I take Timolina?
Take Timolina exactly as it was prescribed for you. Do not take the medication in larger amounts or for longer than recommended by your doctor.
Take this medication with a full glass of water.
Take Timolina at the same time every day.
Do not skip doses or stop taking Timolina without first talking to your doctor. Stopping suddenly may make your condition worse.
To be sure this medication is helping your condition, your blood pressure will need to be checked on a regular basis. It is important that you not miss any scheduled visits to your doctor.
If you need to have any type of surgery, tell the surgeon that you are using Timolina. You may need to briefly stop using Timolina before having surgery.
Timolina is only part of a complete program of treatment for hypertension that may also include diet, exercise, and weight control. Follow your diet, medication, and exercise routines very closely if you are being treated for hypertension.
Hypertension often has no symptoms, so you may not even feel that you have high blood pressure. Continue using this medicine as directed, even if you feel well. You may need to use blood pressure medication for the rest of your life.
Store Timolina at room temperature away from moisture and heat.
Timolina administration
Take Timolina exactly as it was prescribed for you. Do not take the medication in larger amounts or for longer than recommended by your doctor.
Take this medication with a full glass of water.
Take Timolina at the same time every day.
Do not skip doses or stop taking Timolina without first talking to your doctor. Stopping suddenly may make your condition worse.
To be sure this medication is helping your condition, your blood pressure will need to be checked on a regular basis. It is important that you not miss any scheduled visits to your doctor.
If you need to have any type of surgery, tell the surgeon that you are using Timolina. You may need to briefly stop using Timolina before having surgery.
Timolina is only part of a complete program of treatment for hypertension that may also include diet, exercise, and weight control. Follow your diet, medication, and exercise routines very closely if you are being treated for hypertension.
Hypertension often has no symptoms, so you may not even feel that you have high blood pressure. Continue using this medicine as directed, even if you feel well. You may need to use blood pressure medication for the rest of your life.
Store Timolina at room temperature away from moisture and heat.
Timolina pharmacology
Timolina (Timolina) is a beta (non-selective) adrenergic receptor blocking agent that does not have significant intrinsic sympathomimetic, direct myocardial depressant, or local anesthetic activity.
Pharmacodynamics
Clinical pharmacology studies have confirmed the beta-adrenergic blocking activity as shown by (1) changes in resting heart rate and response of heart rate to changes in posture; (2) inhibition of isoproterenol-induced tachycardia; (3) alteration of the response to the Valsalva maneuver and amyl nitrite administration; and (4) reduction of heart rate and blood pressure changes on exercise.
Timolina (Timolina) decreases the positive chronotropic, positive inotropic, bronchodilator, and vasodilator responses caused by beta-adrenergic receptor agonists. The magnitude of this decreased response is proportional to the existing sympathetic tone and the concentration of Timolina (Timolina) at receptor sites.
In normal volunteers, the reduction in heart rate response to a standard exercise was dose dependent over the test range of 0.5 to 20 mg, with a peak reduction at 2 hours of approximately 30% at higher doses.
Beta-adrenergic receptor blockade reduces cardiac output in both healthy subjects and patients with heart disease. In patients with severe impairment of myocardial function beta-adrenergic receptor blockade may inhibit the stimulatory effect of the sympathetic nervous system necessary to maintain adequate cardiac function.
Beta-adrenergic receptor blockade in the bronchi and bronchioles results in increased airway resistance from unopposed parasympathetic activity. Such an effect in patients with asthma or other bronchospastic conditions is potentially dangerous.
Clinical studies indicate that Timolina (Timolina) at a dosage of 20-60 mg/day reduces blood pressure without causing postural hypotension in most patients with essential hypertension. Administration of Timolina (Timolina) to patients with hypertension results initially in a decrease in cardiac output, little immediate change in blood pressure, and an increase in calculated peripheral resistance. With continued administration of Timolina (Timolina), blood pressure decreases within a few days, cardiac output usually remains reduced, and peripheral resistance falls toward pretreatment levels. Plasma volume may decrease or remain unchanged during therapy with Timolina (Timolina). In the majority of patients with hypertension Timolina (Timolina) also decreases plasma renin activity. Dosage adjustment to achieve optimal antihypertensive effect may require a few weeks. When therapy with Timolina (Timolina) is discontinued, the blood pressure tends to return to pretreatment levels gradually. In most patients the antihypertensive activity of Timolina (Timolina) is maintained with long-term therapy and is well tolerated.
The mechanism of the antihypertensive effects of beta-adrenergic receptor blocking agents is not established at this time. Possible mechanisms of action include reduction in cardiac output, reduction in plasma renin activity, and a central nervous system sympatholytic action.
A Norwegian multi-center, double-blind study compared the effects of Timolina maleate with placebo in 1,884 patients who had survived the acute phase of a myocardial infarction. Patients with systolic blood pressure below 100 mm Hg, sick sinus syndrome and contraindications to beta blockers, including uncontrolled heart failure, second or third degree AV block and bradycardia ( < 50 beats per minute), were excluded from the multi-center trial. Therapy with Timolina (Timolina), begun 7 to 28 days following infarction, was shown to reduce overall mortality; this was primarily attributable to a reduction in cardiovascular mortality. Timolina (Timolina) significantly reduced the incidence of sudden deaths (deaths occurring without symptoms or within 24 hours of the onset of symptoms), including those occurring within one hour, and particularly instantaneous deaths (those occurring without preceding symptoms). The protective effect of Timolina (Timolina) was consistent regardless of age, sex or site of infarction. The effect was clearest in patients with a first infarction who were considered at a high risk of dying, defined as those with one or more of the following characteristics during the acute phase: transient left ventricular failure, cardiomegaly, newly appearing atrial fibrillation or flutter, systolic hypotension, or SGOT (ASAT) levels greater than four times the upper limit of normal. Therapy with Timolina (Timolina) also reduced the incidence of non-fatal reinfarction. The mechanism of the protective effect of Timolina (Timolina) is unknown.
Timolina (Timolina) was studied for the prophylactic treatment of migraine headache in placebo-controlled clinical trials involving 400 patients, mostly women between the ages of 18 and 66 years. Common migraine was the most frequent diagnosis. All patients had at least two headaches per month at baseline. Approximately 50 percent of patients who received Timolina (Timolina) had a reduction in the frequency of migraine headache of at least 50 percent, compared to a similar decrease in frequency in 30 percent of patients receiving placebo. The most common cardiovascular adverse effect was bradycardia (5%).
Pharmacokinetics and Metabolism
Timolina (Timolina) is rapidly and nearly completely absorbed (about 90%) following oral ingestion. Detectable plasma levels of Timolina occur within one-half hour and peak plasma levels occur in about one to two hours. The drug half-life in plasma is approximately 4 hours and this is essentially unchanged in patients with moderate renal insufficiency. Timolina is partially metabolized by the liver and Timolina and its metabolites are excreted by the kidney. Timolina is not extensively bound to plasma proteins; i.e., < 10% by equilibrium dialysis and approximately 60% by ultrafiltration. An in vitro hemodialysis study, using C Timolina added to human plasma or whole blood, showed that Timolina was readily dialyzed from these fluids; however, a study of patients with renal failure showed that Timolina did not dialyze readily. Plasma levels following oral administration are about half those following intravenous administration indicating approximately 50% first pass metabolism. The level of beta sympathetic activity varies widely among individuals, and no simple correlation exists between the dose or plasma level of Timolina maleate and its therapeutic activity. Therefore, objective clinical measurements such as reduction of heart rate and/or blood pressure should be used as guides in determining the optimal dosage for each patient.
References
- DailyMed. "TIMOLOL: DailyMed provides trustworthy information about marketed drugs in the United States. DailyMed is the official provider of FDA label information (package inserts).". https://dailymed.nlm.nih.gov/dailyme... (accessed September 17, 2018).
- NCIt. "Timolol Maleate: NCI Thesaurus (NCIt) provides reference terminology for many systems. It covers vocabulary for clinical care, translational and basic research, and public information and administrative activities.". https://ncit.nci.nih.gov/ncitbrowser... (accessed September 17, 2018).
- EPA DSStox. "(S)-Timolol: DSSTox provides a high quality public chemistry resource for supporting improved predictive toxicology.". https://comptox.epa.gov/dashboard/ds... (accessed September 17, 2018).
Reviews
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Information checked by Dr. Sachin Kumar, MD Pharmacology
