First generation H1-antihistamines (such as diphenhydramine = Benadryl) are well known for their sedative effects explaining their limited use in patients with allergic rhinitis. Several pharmacological studies have shown that diphenhydramine crosses the blood brain barrier and produces CNS sedation.
Two studies have (partly) addressed your question ...
If you take coffee daily, you no longer get a boost from it after about a week, but rather, you're just staving off the harsh withdrawal symptoms, not to mention over time it will physically change your brain to have more adenosine receptors i.e., "sleepiness receptors". (Ramkumar V et al, J Clin Invest 82:242-247) in a process known as upregulation
"A 1995 ...
Pneumococcal pneumonia was the most prevalent form of bacterial pneumonia in the community at over 70% of cases but that number has drastically fallen presumably due to the use of pneumococcal vaccines.
Antibiotics are the mainstay of treatment in S pneumoniae infections. Until the 1970s, essentially all pneumococcal isolates were sensitive to easily ...
Yes, unfortunately, Ritalin produces a tolerance in individuals who take it.
In the conclusion of this double blind trial, the author notes,
Acute tolerance to methylphenidate appears to exist. This should be
considered in the design of an optimal dosing regimen for the
treatment of children with attention deficit hyperactivity disorder.
I have found an article published in November 2017 that states:
"Evidence supported consumption of ≤400 mg/day in adults is not associated with overt, adverse effects."
Link to the article:
You can see the meaning of 400 mg of caffeine at this webpage:
Drugs may have different actions at different concentrations.
So, for instance:
Buprenorphine is 25 to 100 times more potent than morphine.18 Buprenorphine exhibits partial agonist behavior at the mu-receptor and exhibits antagonist behavior at the kappa-receptor. Buprenorphine has a strong affinity for the mu-receptor causing tight binding and therefore ...