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Patients with pheochromocytoma.
Care should be taken in the administration of carvedilol to patients with diabetes mellitus, as the early signs and symptoms of acute hypoglycemia may be masked or attenuated. In congestive heart failure patients with diabetes, the use of carvedilol may be associated with worsening control of blood glucose. Therefore, regular monitoring of blood glucose is required in diabetics when carvedilol is initiated or up-titrated and hypoglycemic therapy adjusted accordingly.
Care should be taken in administration of carvedilol to patients with a history of serious hypersensitivity reactions and in those undergoing desensitization therapy as β-blockers may increase both the sensitivity towards allergens and the seriousness of anaphylactic reactions.
Patients with a history of psoriasis associated with β-blocker therapy should take carvedilol only after consideration of the risk-benefit ratio.
When administered to patients who have ischemic heart disease, diffuse angiosis or renal adequacy with hypotension (systolic blood pressure <100mmHg), reversible renal dysfunction may occur. Therefore, in case of initial administration and dosage increase, renal function should be monitored. So, dosage of this drug should be reduced or discontinued in case of aggravation of renal dysfunction.
Clinical experiences of unstable angina have been few. It should be taken with caution in administering this drug to patients who have these signs or symptoms.
Since β-blocker may aggravate or stimulate symptoms of blood flow, patients with peripheral vascular disease should be careful, particularly in case of Raynaud's disease, symptoms may be aggravated.
When it is administered initially or dosage is increased to patients with cardiac failure over NYHA class II, insufficiency of salts and/or body fluids (administering high dosage of diuretic), hypotension (administration of initial systolic BP less than 100 mmHg) and the elderly over 70 years, effects of descending blood pressure may be amplified. Therefore, it should be taken with caution and observed until 2 hours after administration.
When treatment with carvedilol and clonidine together is to be terminated, carvedilol should be withdrawn first, several days before gradually decreasing the dosage of clonidine. (Except in case of some adequate reason.)
Carvedilol treatment should not be discontinued abruptly (particularly, frequency and pain of angina seizure may be severe in patients suffering from chronic stable angina and ischemic heart disease, rarely, myocardial infarction or transient blood pressure rise may occur). The withdrawal of carvedilol in these patients should be gradual (1-2 weeks).
Agents with non-selective β-blocking activity may provoke chest pain in patients with Prinzmetal's variant angina. There has been no clinical experience with carvedilol in these patients although the α-blocking activity may prevent such symptoms. However, caution should be taken in the administration of carvedilol to patients suspected of having Prinzmetal's variant angina.
When cardiac rate drops to less than 55 times/min, dosage is gradually reduced and it should be carefully administered in case of 1st degree AV block.
Carvedilol, like other agents with β-blocking properties, may obscure the symptoms of cardiothyrotoxicosis.
Wearers of contact lenses should bear in mind the possibility of reduced lacrimation.
Individual varying reactions can impair alertness such as patients' capacity for driving or operating machinery. This applies particularly when starting or changing treatment and in conjunction with alcohol.
