Twinblok M

Uses

Cilnidipine is used for the management of hypertension for end-organ protection. It is reported to be useful in elderly patients and in those with diabetes and albuminuria. Cilnidipine has been increasingly used in patients with chronic kidney disease.

Hypertension is the term used to describe the presence of high blood pressure. The blood pressure is generated by the force of the blood pumped from the heart against the blood vessels. Thus hypertension is caused when there is too much pressure on the blood vessels and this effect can damage the blood vessel

ln the management of hypertension and angina pectoris. Cardiac arrhythmias, especially supraventricular tachyarrhythmias. Adjunct to the treatment of hyperthyroidism. Early intervention with Metoprolol in acute myocardial infarction reduces infarct size and the incidence of ventricular fibrillation. Pain relief may also decrease the need for opiate analgesics. Metoprolol has been shown to reduce mortality when administered to patients with acute myocardial infarction.

Twinblok M is also used to associated treatment for these conditions: High Blood Pressure (Hypertension)Angina Pectoris, Atrial Fibrillation, High Blood Pressure (Hypertension), Migraine, Myocardial Infarction, Tachycardia, Supraventricular, Thyroid Crisis, Acute hemodynamically stable Myocardial infarction, Chronic heart failure with reduced ejection fraction (NYHA Class II), Chronic heart failure with reduced ejection fraction (NYHA Class III)

How Twinblok M works

Cilnidipine acts on the L-type calcium channels of blood vessels by blocking the incoming calcium and suppressing the contraction of blood vessels, thereby reducing blood pressure. Cilnidipine also works on the N-type calcium channel located at the end of the sympathetic nerve, inhibiting the emission of norepinephrine and suppressing the increase in stress blood pressure.

Metoprolol is a beta-1-adrenergic receptor inhibitor specific to cardiac cells with negligible effect on beta-2 receptors. This inhibition decreases cardiac output by producing negative chronotropic and inotropic effects without presenting activity towards membrane stabilization nor intrinsic sympathomimetics.

Dosage

Twinblok M dosage

5-10 mg once daily, increase to 20 mg once daily if necessary.

Oral-

Hypertension: Total daily dosage Metoprolol 100-400 mg to be given as a single or twice daily dose. The starting dose is 100 mg (two Metoprolol-50 tablets) per day. This may be increased by 100 mg per day at weekly intervals. lf full control is not achieved using a single daily dose, a b.i.d. regimen should be initiated. Combination therapy with a diuretic or other anti-hypertensive agent may also be considered.

Angina: Usually Metoprolol 50 mg (one Metoprolol-50 tablet) to 100 mg (two Metoprolol-50 tablets)twice or three times daily.

Cardiac arrhythmias: Metoprolol 50 mg (one Metoprolol-50 tablet) b.i.d or t.i.d should usually control the condition. It necessary the dose can be increased up to 300 mg per day in divided doses. Following the treatment of an acute arrhythmia with Metoprolol injection, continuationtherapy with Metoprolol tablets should be initiated 4-6 hours later. The initial oral dose should not exceed 50 mg t.i.d.

Hyperthyroidism: Metoprolol 50 mg (one Metoprolol-50 tablet) four times a day.The dose should bereduced as the euthyroid state is achieved.

Myocardial infarction: Orally, therapy should commence 15 minutes after the last injection with50 mg every 6 hours for 48 hours. Patients who fail to tolerate the full intravenous dose should begiven half the suggested oral dose. Maintenance – The usual maintenance dose is 200 mg dailygiven in divided doses. Elderly’ There are no special dosage requirements in otherwise healthyelderly patients. Signidcant hepatic dysfunction: A reduction in dosage may be necessary.

Injection-

Arrhythmias: By intravenous injection, up to 5 mg at a rate of 1-2 mg/minute, repeated after 5 minutes if necessary, total dose 10-15 mg.

In surgery: By slow intravenous injection 2-4 mg at induction or to control arrhythmias developing during anaesthesia; 2 mg doses may be repeated to a maximum of 10 mg.

Myocardial Infarction: Early intervention within 12 hours of infarction, by intravenous injection 5 mg every 2 minutes to a maximum of 15 mg, followed after 15 minutes by 50 mg by mouth every 6 hours for 48 hours; maintenance 200 mg daily in divided doses.

Impaired Renal Function: Dose adjustment is not needed in patients with impaired renal function.

Impaired Hepatic Function: Dose adjustment is not normally needed in patients suffering from liver cirrhosis because Metoprolol has low protein binding (5-10%). When there are signs of serious impairment of liver function (e.g. shunt-operated patients), a reduction in dose should be considered.

Elderly: Dose adjustment is not needed.

Side Effects

Dizziness; flushing; headache; hypotension; peripheral oedema; tachycardia; palpitations; GI disturbances; increased micturition frequency; lethargy; eye pain; depression; ischaemic chest pain; cerebral or myocardial ischaemia; transient blindness; rashes; fever; abnormal liver function; gingival hyperplasia; myalgia; tremor; impotence.

Bradycardia, bronchospasm, hypotension, headache, fatigue, sleep & gastro-intestinal disturbances, dizziness, vertigo, visual disturbances etc.

Toxicity

The percentage of reports of cilnidipine that express drug toxicity reported as side effects are 5.26%.

Oral administration of metoprolol to rats presents an LD50 in the range of 3090 to 4670 mg/kg. Cases of overdose have reported bradycardia, hypotension, bronchospasm, and cardiac failure. In the case of an overdose, gastric lavage is recommended followed by specific treatment according to symptoms.

Metoprolol is not reported to be carcinogenic nor mutagenic nor to impair fertility. The only event registered is the increase of macrophages in pulmonary alveoli and slight biliary hyperplasia. When metoprolol was given for long periods of time on the highest dose, there was evidence of small benign lung tumors.

Precaution

Hypotension, poor cardiac reserve, heart failure. Sudden withdrawal may exacerbate angina. Discontinue in patients who experience ischemic pain following administration. Pregnancy, lactation.

The second or third dose should not be given if the heart rate is <40 beats/minute, the P-R interval is > 0.26 seconds and the systolic blood pressure is <90 mmHg or if there is any aggravation of dyspnoea or cold sweating. Intravenous administration of calcium antagonists of the Verapamil-type should not be given to patients treated with beta-blockers. When treating patients with suspected or definite myocardial infarction, the haemodynamic status of the patient should be carefully monitored after each of the three 5 mg intravenous doses. Use in Pregnancy: As with most medicines, Metoprolol should not be given during pregnancy and lactation unless its use is considered essential. As with all antihypertensive agents, beta-blockers may cause side effects (e.g. bradycardia) in the foetus and in the newborn and breast-fed infant. Use in Lactation: The amount of Metoprolol ingested via breast-milk seems to be negligible as regards beta-blocking effect in the infant if the mother is treated with Metoprolol doses within the normal therapeutic range.

Interaction

Other antihypertensives; aldesleukin; antipsychotics that cause hypotension; may modify insulin and glucose responses; quinidine; carbamazepine; phenytoin; rifampicin; cimetidine; erythromycin.

Plasma level of Metoprolol may be raised by co-administration of compounds metabolished by CYP2D6 e.g. Antiarrhythmics, antihistamines, H2 receptor antagonists, antidepressants, antipsychotics and COX-2 inhibitors. The plasma conc. of Metoprolol is lowered by Rifampicin.

Volume of Distribution

Drugs on the group of dihydropyridines such as cilnidipine tend to have a large volume of distribution.

The reported volume of distribution of metoprolol is 4.2 L/kg. Due to the characteristics of metoprolol, this molecule is able to cross the blood-brain barrier and even 78% of the administered drug can be found in cerebrospinal fluid.

Elimination Route

Cilnidipine presents a very rapid absorption with a maximum peaked concentration after 2 hours. Its distribution tends to be higher in the liver as well as in kidneys, plasma and other tissues. Cilnidipine does not present a high accumulation in the tissue after repeated oral administration.

Cilnidipine is reported to present very low bioavailability determined to be approximately 13%. This low bioavailability is suggested to be due to its low aqueous solubility and high permeability. Hence, efforts have been made in order to find an innovative formulation that can significantly improve the bioavailability of this drug. One of these formulations corresponds to the generation of polymeric nanoparticles which enhance the bioavailability by 2.5-3-fold.

When metoprolol is administered orally, it is almost completely absorbed in the gastrointestinal tract. The maximum serum concentration is achieved 20 min after intravenous administration and 1-2 hours after oral administration. The bioavailability of metoprolol is of 100% when administered intravenously and when administered orally it presents about 50% for the tartrate derivative and 40% for the succinate derivative.

The absorption of metoprolol in the form of the tartrate derivative is increased by the concomitant administration of food.

Half Life

The half-life of the hypotensive effect for cilnidipine is of about 20.4 min.

The immediate release formulations of metoprolol present a half-life of about 3-7 hours.

Clearance

The reported clearance rate on patients with normal kidney function is 0.8 L/min. In cirrhotic patients, the clearance rate changes to 0.61 L/min.

Elimination Route

Cilnidipine gets eliminated through the urine in a proportion of 20% of the administered dose and 80% is eliminated by the feces.

Metoprolol is mainly excreted via the kidneys. From the eliminated dose, less than 5% is recovered unchanged.

Pregnancy & Breastfeeding use

No specific information about USFDA pregnancy category. Caution should be exercised during Cilnidipine use in pregnancy. Nursing mothers should consult a physician before taking Cilnidipine.

Metoprolol should not be used in pregnancy or lactating mothers unless the physician considers that the benefit outweighs the possible hazard to the fetus or infant.

Contraindication

Cardiogenic shock; recent MI or acute unstable angina; severe aortic stenosis.

2nd or 3rd degree AV block, sick sinus syndrome, hypotension, decompensated heart failure, sinus bradycardia, severe peripheral arterial circulatory disorders, cardiogenic shock, severe asthma and bronchospasm, untreated phaeochromocytoma, Prinzmetal's angina, metabolic acidosis.

Special Warning

Renal Impairment: No dosage adjustment needed.

Hepatic Impairment: Reduce dose.

Acute Overdose

Poisoning due to an overdose of metoprolol may lead to severe hypotension, sinus bradycardia, atrioventricular block, heart failure, cardiogenic shock, cardiac arrest, bronchospasm, impairment of consciousness, coma, nausea, vomiting, cyanosis, hypoglycaemia and, occasionally, hyperkalaemia. The first manifestations usually appear 20 minutes to 2 hours after drug ingestion. Treatment: Treatment should include close monitoring of cardiovascular, respiratory and renal function, and blood glucose and electrolytes. Further absorption may be prevented by induction of vomiting, gastric lavage or administration of activated-charcoal if ingestion is recent. Cardiovascular complications should be treated symptomatically, which may require the use of sympathomimetic agents (e.g. noradrenaline, metaramionl), atropine or inotropic agents (e.g. dopamine, dobutamine). Temporary pacing may be required for AV block. Glucagon can reverse the effects of excessive B-blockade, given in a dose of 1-10 mg intravenously. Intravenous B2-stimulants e.g. terbutaline may be required to relieve bronchospasm. Metoprolol cannot be effectively removed by haemodialysis.

Storage Condition

Store in a cool, dry place protected from light. Keep out of reach of children.

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