10 Questions
What determines whether a compound acts as a medicine or a poison?
The dose level of the compound
All drugs are completely safe and have no side effects.
False
What is the therapeutic index of a drug?
A measure of a drug's beneficial effects at a low dose versus its harmful effects at a higher dose.
The idea that 'everything is a poison, nothing is a poison' is based on the concept that ______________________.
it is the dose that makes the poison
Match the following terms with their definitions:
Selective toxicity = The ability of a drug to target problematic cells without harming healthy cells Therapeutic index = A measure of a drug's beneficial effects at a low dose versus its harmful effects at a higher dose Protozoa = A polyphyletic group of single-celled eukaryotes that feed on organic matter Antiprotozoal drugs = Drugs that show selective toxicity to microbial cells rather than mammalian cells
What is the principle of selective toxicity?
Drugs show toxicity against foreign or abnormal cells but not against normal host cells.
The cell membrane is composed only of phospholipids.
False
What is the role of the hydrophobic tails in the cell membrane?
To maximize hydrophobic interactions with each other and stay away from aqueous environments.
The cell membrane is made up of a variety of proteins situated in the ______________________.
phospholipid bilayer
Match the following components of the cell membrane with their descriptions:
Phosphatidylcholine = Outer membrane component Phosphatidylserine = Inner membrane component Phosphatidylethanolamine = Inner membrane component Phosphatidylinositol = Inner membrane component
Study Notes
Drugs and Poisons
- All medicines have the potential to become poisonous if taken in excess, making it essential to treat them with respect.
- The therapeutic index measures a drug's beneficial effects at a low dose versus its harmful effects at a high dose, indicating its safety.
Definition of Drugs
- Drugs are compounds that interact with biological systems to produce a biological response.
- The concept of poisons acting as drugs is exemplified by penicillin, which interacts with bacteria to produce a biological response, but has no effect on human cells.
Selective Toxicity
- Many drugs are effective because they are toxic to problematic cells, such as microbial cells, rather than healthy or normal cells.
- Antiprotozoal drugs are useful in medicine because they show selective toxicity to microbial cells rather than mammalian cells.
- Clinically effective anticancer agents show selective toxicity for cancer cells over normal cells, and effective antiviral agents are toxic to viruses rather than normal cells.
Safety of Drugs
- No drug is entirely safe, and they vary in the side effects they may have.
- The dose level of a compound determines whether it will act as a medicine or poison.
- A high therapeutic index indicates a large safety margin between beneficial and toxic doses.
Chemical Structure and Human Body
- The human body operates at a molecular level, with many chemical reactions taking place to keep it healthy and functioning.
- Drugs interact with the body's chemical reactions and can affect cell structure.
Cell Structure and Function
- The cell membrane is a boundary wall that encloses the cell's contents, the cytoplasm.
- The cell membrane is composed of phospholipids, with a specific arrangement of hydrophobic tails and ionic head-groups.
- This structure results in a fatty layer between the cell and its surroundings, allowing the cell to regulate its interactions with the environment.
Learn about the therapeutic index, a measure of a drug's safety, and the importance of treating all medicines with respect due to their potential to become poisonous at high doses.
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