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Inamrinone (Inamrinone) - Side Effects and Adverse Reactions

 
 



ADVERSE REACTIONS

Thrombocytopenia: Intravenous injection of inamrinone resulted in platelet count reductions to below 100,000/mm3 or normal limits in 2.4 percent of the patients.

It is more common in patients receiving prolonged therapy. To date, in closely-monitored clinical trials, in patients whose platelet counts were not allowed to remain depressed, no bleeding phenomena have been observed.

Platelet reduction is dose dependent and appears due to a decrease in platelet survival time. Several patients who developed thrombocytopenia while receiving inamrinone had bone marrow examinations which were normal. There is no evidence relating platelet reduction to immune response or to a platelet activating factor.

Gastrointestinal Effects: Gastrointestinal adverse reactions reported with inamrinone during clinical use included nausea (1.7%), vomiting (0.9%), abdominal pain (0.4%), and anorexia (0.4%).

Cardiovascular Effects: Cardiovascular adverse reactions reported with inamrinone include arrhythmia (3%) and hypotension (1.3%).

Hepatic Toxicity: In dogs, at IV doses between 9 mg/kg/day and 32 mg/kg/day, inamrinone showed dose-related hepatotoxicity manifested either as enzyme elevation or hepatic cell necrosis or both. Hepatotoxicity has been observed in man following long-term oral dosing and has been observed, in a limited experience (0.2%), following intravenous administration of inamrinone. There have also been rare reports of enzyme and bilirubin elevation and jaundice.

Hypersensitivity: There have been reports of several apparent hypersensitivity reactions in patients treated with oral inamrinone for about two weeks. Signs and symptoms were variable but included pericarditis, pleuritis and ascites (1 case), myositis with interstitial shadowing on chest x-ray and elevated sedimentation rate (1 case) and vasculitis with nodular pulmonary densities, hypoxemia, and jaundice (1 case). The first patient died, not necessarily of the possible reaction, while the last two resolved with discontinuation of therapy. None of the cases were rechallenged so that attribution to inamrinone is not certain, but possible hypersensitivity reactions should be considered in any patient maintained for a prolonged period on inamrinone.

General: Additional adverse reactions observed in intravenous inamrinone clinical studies include fever (0.9%), chest pain (0.2%), and burning at the site of injection (0.2%).

Management of Adverse Reactions

Platelet Count Reductions: Asymptomatic platelet count reduction (to <150,000/mm3) may be reversed within one week of a decrease in drug dosage. Further, with no change in drug dosage, the count may stabilize at lower than pre-drug levels without any clinical sequelae. Pre-drug platelet counts and frequent platelet counts during therapy are recommended to assist in decisions regarding dosage modifications.

Should a platelet count less than 150,000/mm3 occur, the following actions may be considered:

  • Maintain total daily dose unchanged, since in some cases counts have either stabilized or returned to pretreatment levels.
  • Decrease total daily dose.
  • Discontinue inamrinone if, in the clinical judgment of the physician, risk exceeds the potential benefit.

Gastrointestinal Side Effects: While gastrointestinal side effects were seen infrequently with intravenous therapy, should severe or debilitating ones occur, the physician may wish to reduce dosage or discontinue the drug based on the usual benefit-to-risk considerations.

Hepatic Toxicity: In clinical experience to date with intravenous administration, hepatotoxicity has been observed rarely. If acute marked alterations in liver enzymes occur together with clinical symptoms suggesting an idiosyncratic hypersensitivity reaction, inamrinone therapy should be promptly discontinued.

If less than marked enzyme alterations occur without clinical symptoms, these nonspecific changes should be evaluated on an individual basis. The clinician may wish to continue inamrinone, reduce dosage, or discontinue the drug based on the usual benefit/risk considerations.

Drug label data at the top of this Page last updated: 2006-10-11

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