PPA: English abbreviation for phenylpropanolamine hydrochloride, which is a synthetic sympathomimetic amine. Its structure is similar to adrenaline, phenylephrine, ephedrine and amphetamine, and it is contained in many drugs for treating colds and suppressing appetite.
First, the description of PPA in foreign pharmacopoeia
Adrenergic receptor agonist phenylpropanolamine hydrochloride. Pharmacopoeia of Australia, Britain, France, Germany, Italy, New Zealand, Portugal, Switzerland and the United States have all been collected. Don't call it Mydriatin.
Properties and stability: this product is white or white-like crystalline powder; Slightly fragrant, soluble in water and ethanol, insoluble in chloroform, insoluble in ether and chloroform, this product has stable properties.
In vivo process: it is absorbed quickly after oral administration, and the peak time of plasma is about 1-2 hours, which is mainly excreted through urine. Drug action: this product is a sympathomimetic drug, that is, adrenergic receptor agonist. Its effect is similar to ephedrine, and it has contractive effect on skin mucosa and visceral blood vessels, but the central nervous system has less exciting effect. Oral administration can treat nasal congestion, so it is often combined with antipyretic and analgesic drugs and histamine antagonists to relieve cold symptoms.
Indications: used for colds, relieving nasal congestion, sneezing and coughing.
Adverse reactions and precautions: occasional central nervous system excitement with tremor, headache, blurred vision, dizziness, anxiety, insomnia, transient hypertension, palpitation, etc. Patients with heart disease, diabetes, hypertension and hyperthyroidism and those who are allergic to this product are prohibited. As an over-the-counter drug, this product is limited to compound preparations. Not suitable for children aged 6- 12 years, unless medication is under the guidance of a doctor.
Drug Interaction: This product should not be combined with thiazides, otherwise severe ventricular fibrillation will occur.
Administration and dosage: oral. Adults should not exceed 25mg at a time, three times a day.
Limited dosage form: compound preparation.
Its therapeutic effect: phenylpropanolamine hydrochloride has vasoconstrictive effect, thus reducing nasal mucosal swelling; He and chlorpheniramine are antihistamines, which can competitively block the effect of histamine H 1 receptor. Acetaminophen plays an antipyretic role by regulating the hypothalamic thermoregulatory center. Dextromethorphan hydrobromide has antitussive effect. The combination of several drugs has the effect of treating colds. Therefore, some capsules and compound preparations are used for symptoms such as fever, headache, limb aches, cough, stuffy nose, runny nose, tears and sneezing caused by colds.
Clinical value of phenylpropanolamine
Phenylpropanolamine is a sympathomimetic drug, which is similar to stimulating sympathetic nerve. Generally speaking, sympathetic nerve excitation is a vasoconstrictive effect, but it is a relaxing effect on bronchial smooth muscle.
The medicine is clinically used in cardiovascular, respiratory, ophthalmology, urogenital system, etc. It is helpful for treating hypovolemic shock, cardiogenic shock, anaphylactic shock and bronchial asthma, eliminating nasal congestion caused by cold, and increasing blood pressure and blood flow for patients with hypotension.
Now "3G communication" is about to become the mantra in people's mouths, so do you know what 3G communication is? The so-called 3G, in fact, is the third generation, which means the third generation digital communication in Chinese. 1995, the first generation of digital mobile phones, can only make voice calls; The second generation digital mobile phones from 1996 to 1997 have added the function of receiving data, such as accepting emails or web pages; The main difference between the third generation and the first two generations is that the speed of transmitting sound and data has increased. It can handle various media forms, such as images, music and video streams, and provide various information services, including web browsing, teleconference and e-commerce. Compared with the first generation analog mobile phones (1G) and the second generation GSM, TDMA and other digital mobile phones (2G),
There are many names for 3G communication. ITU defines it as "IMT-2000" (International Mobile Phone 2000), and European telecom giants call it "UMTS" universal mobile telecommunications system. According to the standard, when the mobile terminal moves at vehicle speed, its data transmission rate is 144kbps, the outdoor stationary or walking speed is 384kbps, and the indoor speed is 2Mbps. However, these requirements do not mean that the available rate of users can reach 2Mbps, because the indoor rate will also depend on the detailed frequency planning in the building and the close cooperation between organizations and operators.
The International Telecommunication Union (ITU) has determined three mainstream wireless interface standards for 3G communication, namely W-CDMA (Wideband Code Division Multiple Access), CDMA2000 (Multicarrier Wavelength Division Multiplexing Spread Spectrum Modulation) and TDS-CDMA (time division-synchronous code division multiple access). Among them, the W-CDMA standard mainly originated from the early third-generation wireless research activities in Europe and Japan. The system is used on the existing GSM network and can be easily converted by system providers. The main supporters of this standard are Europe, Japan and South Korea. At the end of last year, at&; T Mobile Services Branch also announced that it has chosen WCDMA as its third generation service platform. CDMA2000 system is mainly proposed by Qualcomm North America Company, and its construction cost is relatively low. Its main supporters include Japan, South Korea and North America. TD-SCDMA standard was first put forward by China, and cooperated with the international community on the basis of RTT. TD-SCDMA standard is completed and becomes a member of CDMA TDD standard. This is a pioneering work in the field of mobile communication in China, and also China's contribution to the development of the third generation mobile communication. In the competition with the 3G standards proposed by Europe and America respectively, TD-SCDMA proposed by China has officially become one of the global 3G standards, which indicates that China has entered a leading position in the field of mobile communication.
3G mobile phone is the product of the integration of communication industry and computer industry. Compared with the previous mobile phone, the difference is too great, so more and more people begin to call this new mobile communication product "personal communication terminal". Even the most layman in the communication industry can easily judge whether a mobile phone is the "third generation" from its appearance: the third generation mobile phones have a large color display screen, which is often touch-sensitive. 3G mobile phone can not only complete high-quality daily communication, but also carry out multimedia communication. Users can write and draw directly on the touch screen of 3G mobile phone and send it to another mobile phone, which may take less than one second. Of course, you can also send this information to the computer or download some information from the computer; Users can use 3G mobile phones to surf the Internet directly, check emails or browse the web. There will be many models of 3G mobile phones with their own cameras, which will allow users to hold computer meetings with their mobile phones and even make digital cameras "redundant".
3G communication is a mobile communication service introduced in the mobile communication market after the first generation of analog technology, and it has been introduced into the agenda in the vigorous development of the second generation digital mobile communication market. With the rise of Internet data services and the improvement of fixed access rate (HDSL, ADSL, VDSL), 3G mobile communication system has also seen the dawn of the market, and attracted more and more attention from telecom operators, communication equipment manufacturers and ordinary users.