Tablets can be classified into various types based on their formulation, which determines their drug release characteristics and intended use. The main types of tablets are as follows:
1. Immediate-Release Tablets
Immediate-release tablets are designed to release the entire dose of the drug rapidly upon ingestion. These tablets disintegrate and dissolve quickly in the gastrointestinal tract, allowing the drug to be readily absorbed into the bloodstream. Immediate-release tablets are commonly used for drugs that require a rapid onset of action and do not need prolonged drug release.
2. Extended-Release Tablets
Extended-release tablets, also known as controlled-release or sustained-release tablets, are formulated to release the drug gradually over an extended period. The drug is released at a controlled rate, maintaining therapeutic levels in the bloodstream for a more extended period compared to immediate-release tablets. Extended-release formulations allow for less frequent dosing, enhancing patient compliance and reducing fluctuations in drug concentration.
3. Chewable Tablets
Chewable tablets are formulated to be chewed or crushed before swallowing. They are often used for pediatric patients or individuals who have difficulty swallowing whole tablets. Chewable tablets usually have pleasant flavors to improve patient acceptance.
4. Sublingual Tablets
Sublingual tablets are designed to be placed under the tongue, where the drug is rapidly absorbed through the sublingual mucosa and directly enters the bloodstream, bypassing the gastrointestinal tract. Sublingual administration provides faster onset of action and avoids first-pass metabolism in the liver.
5. Enteric-Coated Tablets
Enteric-coated tablets have a special coating that resists dissolution in the acidic environment of the stomach. Instead, the tablet disintegrates and releases the drug in the more alkaline environment of the intestines. Enteric coating is used for drugs that may cause irritation or degradation in the stomach or require specific site-specific drug release in the intestines.
6. Effervescent Tablets
Effervescent tablets contain a combination of organic acids and carbonates that react with water to release carbon dioxide gas, resulting in effervescence. This effervescence helps in breaking down the tablet and aids in swallowing. Effervescent tablets are particularly useful for patients who have difficulty swallowing conventional tablets or who need rapid drug action.
In summary, tablets come in various formulations to cater to different patient needs and drug requirements. Immediate-release tablets are suitable for drugs needing rapid action, while extended-release formulations are designed for controlled drug release over time. Chewable tablets are preferred for patients who have difficulty swallowing, and sublingual tablets offer rapid absorption. Enteric-coated tablets protect the drug from stomach acid, and effervescent tablets provide a more pleasant administration experience.