Penbutolol Effects and What to Tell Your Doctor
You should talk with your healthcare provider prior to taking penbutolol if you have:
- Kidney disease, such as kidney failure (renal failure)
- Chest pain (angina)
- Heart failure
- A slow heart rate (bradycardia)
- Heart block
- Chronic obstructive pulmonary disease (COPD)
- An upcoming surgery
- Any allergies, including allergies to food, dyes, or preservatives.
Also, let your healthcare provider know if you are:
- Pregnant or thinking of becoming pregnant (see Levatol and Pregnancy)
- Breastfeeding (see Levatol and Breastfeeding).
Make sure to tell your healthcare provider about all other medicines you are taking, including prescription and nonprescription medicines, vitamins, and herbal supplements.
(Click Precautions and Warnings With Penbutolol to learn more, including information on who should not take the drug.)
Penbutolol belongs to a group of drugs called beta-adrenergic blocking agents, known as beta blockers for short. As you might guess, these medications block beta receptors in the body. In addition to blocking beta receptors, however, penbutolol also slightly stimulates them. Only a few beta blockers do this; this slight stimulatory action is known as "intrinsic sympathomimetic activity" or ISA.
Beta receptors are located in a number of places within the body, including the heart and blood vessels. Stress hormones such as adrenaline bind to these receptors and cause certain reactions in the body, such as:
- Increased force with which the heart pumps blood
- Increased heart rate
- Higher blood pressure (both systolic blood pressure and diastolic blood pressure)
- Constricted blood vessels.
By blocking beta receptors, penbutolol causes the reverse effect of stress hormones and reduces blood pressure. It may have less effect on heart rate and the workload of the heart compared to most other beta blockers, due to the fact that it slightly stimulates beta receptors.