Bisoprolol is classified as a 'beta-blocker', a fairly diverse class of drugs with important pharmacologic and pharmacokinetic differences between them.
Three of the main differentiating factors are:
- Lipid solubility
- Sympathomimetic activity
Bisoprolol 'lipid-soluble' and is associated with a feeling of "mental fog". I discuss this further in the next sections.
Beta-Blockers And Lipid Solubility
When it comes to side effects, especially cognitive impairment or sedation, lipid solubility is most likely the key characteristics to be aware of and is what I will be discussing here.
In general, drugs with high lipid solubility readily cross the blood-brain barrier and thus can cause related side effects. Lipid solubility also has a significant effect on metabolism.
Beta-blocker medications run the range from low to high lipid solubility. Two of the highest lipid-soluble ones are propranolol and metoprolol. A low lipid-soluble example is atenolol.
Bisoprolol is generally classified on the low end of the lipid-soluble range but does nonetheless but have associated properties.
Bisoprolol Side Effects
As mentioned, lipid solubility can affect many different characteristics of a drug, including metabolism and side effects.
As bisoprolol does have some lipid-soluble properties, it can cross the blood-brain barrier. This often is associated with central nervous system (CNS) side effects, such as:
- "Mental fog"
- Vivid dreams
According to the prescribing information for bisoprolol, the incidence of these CNS effects is:
- Sedation/Fatigue (8%)
- Dizziness (3%)
- Headache (10%)
- Depression (<0.2%)
- Dreams (reported)
- Cognitive Impairment (reported)
The extent or existence of memory loss or significant cognitive/memory impairment on beta-blockers like bisoprolol is controversial.
A variety of studies have reported these effects but many others have concluded that there are no long term effects and associated symptoms are by-products of the sedative nature of the drugs.
The side effects you described in your inquiry are certainly possible with bisoprolol and have been reported. It is important to discuss them with your doctor and discuss the best course of medication therapy for you.
Bisoprolol is associated with causing a 'mental fog' and mild memory loss. If these side effects are occurring, a change in drug may be appropriate and you should discuss it with your doctor.
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