Actions of Imtack in details
Anti-angina.
Pharmacology: Pharmacodynamics: Clinical Pharmacology:
After therapeutic doses of the drug, systemic arterial pressure is usually decreased; heart rate is unchanged or undergoes a slight compensatory increase. In the absence of heart failure, cardiac output transiently increases and then decreases. Pulmonary vascular resistance and pulmonary pressure are decreased.
The antianginal effects of sublingual Imtack generally occur within 2-5 min after administration and last for 1-2 hrs. The hemodynamic effects of the oral tablets are observed within 20-60 min and last for 4-6 hrs.
Animal Pharmacology:
Pharmacokinetics: Gastrointestinal absorption of Imtack is rapid and complete. The drug undergoes an extensive first-pass effect with some interpatient variation. Imtack is metabolized to 2 mononitrates which subsequently undergo glucuronidation. Less than 1% of Imtack is bound to plasma proteins. Plasma concentrations of Imtack and mononitrates were compared after administration of sublingual (2 x 5 mg) and oral (2 x 10 mg) tablets to volunteers. The sublingual dosage form was more rapidly absorbed than the oral formulation, as evidenced by the earlier peak concentrations of the parent drug and the mononitrates. The t½ of the parent drug was 0.2 and 0.5 hrs for the sublingual and oral tablets, respectively. For 2-Imtack mononitrate, the t½ was 2 hrs for both dosage forms. For 5-Imtack mononitrate, the t½ of the sublingual tablets was 5.8 hrs while that of the oral tablets was 4.5 hrs. With chronic administration, significant plasma accumulation of the parent compound occurs, presumably the result of saturation of the intrahepatic biotransformation process.
The elimination phase after both acute and chronic administration of Imtack appears to be at least bi-exponential. Essentially, all of the drug is eliminated by the kidneys, principally as Imtack glucuronide.
How should I take Imtack?
Take this medication exactly as it was prescribed for you. Do not take the medication in larger amounts, or take it for longer than recommended by your doctor. Follow the directions on your prescription label.
If possible, try to rest or stay seated when you use this medication. Imtack can cause dizziness or fainting.
If you use Imtack to treat an angina attack: Use the medicine at the first sign of chest pain. Place the sublingual tablet under your tongue and allow it to dissolve slowly. Do not chew or swallow it. The chewable tablet should be chewed and then held in the mouth for about 2 minutes before swallowing.
You may use additional tablets every 5 minutes, but not more than 3 tablets in 15 minutes.
Do not crush, chew, break, or open an extended-release tablet or capsule. Swallow the pill whole. It is specially made to release medicine slowly in the body. Breaking or opening the pill would cause too much of the drug to be released at one time. Seek emergency medical attention if your chest pain gets worse or lasts more than 5 minutes, especially if you have trouble breathing or feel weak, dizzy, or nauseated, or lightheaded.
It is important to keep this medicine on hand at all times in case of an angina attack. Get your prescription refilled before you run out of medicine completely.
If you take Imtack on a regular schedule to prevent angina, do not stop taking it suddenly or you could have a severe attack of angina.
Do not change brands of Imtack without the approval of your doctor.
Store Imtack at room temperature, away from moisture, heat, and light. Keep the medicine in its original container.
Throw away any leftover Imtack on the expiration date. Expired Imtack will not treat your condition.
Imtack administration
Take this medication exactly as prescribed by your doctor. Do not take it in larger amounts or for longer than recommended. Follow the directions on your prescription label.
Your doctor may occasionally change your dose to make sure you get the best results from this medication. Imtack is usually taken 2 or 3 times per day. Follow your doctor's dosing instructions very carefully.
If possible, try to rest or stay seated when you use this medication. Imtack can cause dizziness or fainting.
Do not crush, chew, break, or open an extended-release tablet or capsule. Swallow the pill whole. Breaking the pill may cause too much of the drug to be released at one time.
If you expect to engage in an activity that may cause angina, take the sublingual tablet about 15 minutes before the activity.
If you use the sublingual tablet to treat an angina attack that has already begun, use the medicine at the first sign of chest pain. Place the tablet under your tongue and allow it to dissolve slowly. Do not chew or swallow it.
Before using Imtack to treat a sudden angina attack, your doctor may want you to first use a nitroglycerin sublingual tablet. Follow your doctor's instructions about what medications to use during an attack and how much time to allow between doses.
Some things can cause your blood pressure to get too low. This includes vomiting, diarrhea, heavy sweating, heart disease, dialysis, a low-salt diet, or taking diuretics (water pills). Tell your doctor if you have a prolonged illness that causes diarrhea or vomiting.
Seek emergency medical attention if your chest pain gets worse or lasts more than 5 minutes, especially if you have trouble breathing or feel weak, dizzy, or nauseated, or lightheaded.
It is important to keep this medicine on hand at all times in case of an angina attack. Get your prescription refilled before you run out of medicine completely.
If you take Imtack on a regular schedule to prevent angina, do not stop taking it suddenly or you could have a severe attack of angina.
Do not change brands of Imtack without the approval of your doctor.
Store Imtack at room temperature, away from moisture, heat, and light. Keep the bottle tightly closed when not in use.
Imtack pharmacology
The principal pharmacological action of Imtack is relaxation of vascular smooth muscle and consequent dilatation of peripheral arteries and veins, especially the latter. Dilatation of the veins promotes peripheral pooling of blood and decreases venous return to the heart, thereby reducing left ventricular end-diastolic pressure and pulmonary capillary wedge pressure (preload). Arteriolar relaxation reduces systemic vascular resistance, systolic arterial pressure, and mean arterial pressure (afterload). Dilatation of the coronary arteries also occurs. The relative importance of preload reduction, afterload reduction, and coronary dilatation remains undefined.
Dosing regimens for most chronically used drugs are designed to provide plasma concentrations that are continuously greater than a minimally effective concentration. This strategy is inappropriate for organic nitrates. Several well-controlled clinical trials have used exercise testing to assess the anti-anginal efficacy of continuously-delivered nitrates. In the large majority of these trials, active agents were no more effective than placebo after 24 hours (or less) of continuous therapy. Attempts to overcome nitrate tolerance by dose escalation, even to doses far in excess of those used acutely, have consistently failed. Only after nitrates have been absent from the body for several hours has their anti-anginal efficacy been restored.
Pharmacokinetics
Absorption of Imtack after oral dosing is nearly complete, but bioavailability is highly variable (10% to 90%), with extensive first-pass metabolism in the liver. Serum levels reach their maxima about an hour after ingestion. The average bioavailability of Imtack is about 25%; most studies have observed progressive increases in bioavailability during chronic therapy.
Once absorbed, the volume of distribution of Imtack is 2 to 4 L/kg, and this volume is cleared at the rate of 2 to 4 L/min, so Imtack's half-life in serum is about an hour. Since the clearance exceeds hepatic blood flow, considerable extra hepatic metabolism must also occur. Clearance is affected primarily by denitration to the 2-mononitrate (15 to 25%) and the 5-mononitrate (75 to 85%).
Both metabolites have biological activity, especially the 5-mononitrate. With an overall half-life of about 5 hours, the 5-mononitrate is cleared from the serum by denitration to Imtack, glucuronidation to the 5-mononitrate glucuronide, and denitration/hydration to sorbitol. The 2-mononitrate has been less well studied, but it appears to participate in the same metabolic pathways, with a half-life of about 2 hours.
The daily dose-free interval sufficient to avoid tolerance to organic nitrates has not been well defined. Studies of nitroglycerin (an organic nitrate with a very short half-life) have shown that daily dose-free intervals of 10 to 12 hours are usually sufficient to minimize tolerance. Daily dose-free intervals that have succeeded in avoiding tolerance during trials of moderate doses (e.g., 30 mg) of immediate-release Imtack have generally been somewhat longer (at least 14 hours), but this is consistent with the longer half-lives of Imtack and its active metabolites.
Few well-controlled clinical trials of organic nitrates have been designed to detect rebound or withdrawal effects. In one such trial, however, subjects receiving nitroglycerin hadlessexercise tolerance at the end of the daily dose-free interval than the parallel group receiving placebo. The incidence, magnitude, and clinical significance of similar phenomena in patients receiving Imtack have not been studied.
References
- DailyMed. "ISOSORBIDE DINITRATE: 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. "Isosorbide Dinitrate: 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. "Isosorbide dinitrate: 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
