Presenting the Definition, Classification, and Composition of Drug Suspensions.

6. Some examples of emulsions

6.1. Natural emulsion

Prepared from oil seeds and has no pharmacological effect. Convention: one part seed is prepared into 10 parts emulsion.

For example: Peanuts 10g Distilled water 100ml

The emulsion oil phase is the oil in the seeds, the emulsion water phase is distilled water and water in the seeds, the emulsifier is the albumin in the seeds.

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Presents the Definition, Classification, and Composition of Drug Emulsions.
Qos Assurance Methods for Multimedia Communications zt2i3t4l5ee zt2a3gs zt2a3ge zc2o3n4t5e6n7ts low. The EF PHB requires a sufficiently large number of output ports to provide low delay, low loss, and low jitter. EF PHBs can be implemented if the output port's bandwidth is sufficiently large, combined with small buffer sizes and other network resources dedicated to EF packets, to allow the router's service rate for EF packets on an output port to exceed the arrival rate λ of packets at that port. This means that packets with PHB EF are considered with a pre-allocated amount of output bandwidth and a priority that ensures minimum loss, minimum delay and minimum jitter before being put into operation. PHB EF is suitable for channel simulation, leased line simulation, and real-time services such as voice, video without compromising on high loss, delay and jitter values. Figure 2.10 Example of EF installation Figure 2.10 shows an example of an EF PHB implementation. This is a simple priority queue scheduling technique. At the edges of the DS domain, EF packet traffic is prioritized according to the values agreed upon by the SLA. The EF queue in the figure needs to output packets at a rate higher than the packet arrival rate λ. To provide an EF PHB over an end-to-end DS domain, bandwidth at the output ports of the core routers needs to be allocated in advance to ensure the requirement μ > λ. This can be done by a pre-configured provisioning process. In the figure, EF packets are placed in the priority queue (the upper queue). With such a length, the queue can operate with μ > λ. Since EF was primarily used for real-time services such as voice and video, and since real-time services use UDP instead of TCP, RED is generally not suitable for EF queues because applications using UDP will not respond to random packet drop and RED will strip unnecessary packets. 2.2.4.2 Assured Forwarding (AF) PHB PHB AF is defined by RFC 2597. The purpose of PHB AF is to deliver packets reliably and therefore delay and jitter are considered less important than packet loss. PHB AF is suitable for non-real-time services such as applications using TCP. PHB AF first defines four classes: AF1, AF2, AF3, AF4. For each of these AF classes, packets are then classified into three subclasses with three distinct priority levels. Table 2.8 shows the four AF classes and 12 AF subclasses and the DSCP values for the 12 AF subclasses defined by RFC 2597. RFC 2597 also allows for more than three separate priority levels to be added for internal use. However, these separate priority levels will only have internal significance. PHB Class PHB Subclass Package type DSCP AF4 AF41 Short 100010 AF42 Medium 100100 AF43 High 100110 AF3 AF31 Short 011010 AF32 Medium 011100 AF33 High 011110 AF2 AF21 Short 010010 AF22 Medium 010100 AF23 High 010110 AF1 AF11 Short 001010 AF12 Medium 001100 AF13 High 001110 Table 2.8 AF DSCPs The AF PHB ensures that packets are forwarded with a high probability of delivery to the destination within the bounds of the rate agreed upon in an SLA. If AF traffic at an ingress port exceeds the pre-priority rate, which is considered non-compliant or “out of profile”, the excess packets will not be delivered to the destination with the same probability as the packets belonging to the defined traffic or “in profile” packets. When there is network congestion, the out of profile packets are dropped before the in profile packets are dropped. When service levels are defined using AF classes, different quantity and quality between AF classes can be realized by allocating different amounts of bandwidth and buffer space to the four AF classes. Unlike EF, most AF traffic is non-real-time traffic using TCP, and the RED queue management strategy is an AQM (Adaptive Queue Management) strategy suitable for use in AF PHBs. The four AF PHB layers can be implemented as four separate queues. The output port bandwidth is divided into four AF queues. For each AF queue, packets are marked with three “colors” corresponding to three separate priority levels. In addition to the 32 DSCP 1 groups defined in Table 2.8, 21 DSCPs have been standardized as follows: one for PHB EF, 12 for PHB AF, and 8 for CSCP. There are 11 DSCP 1 groups still available for other standards. 2.2.5.Example of Differentiated Services We will look at an example of the Differentiated Service model and mechanism of operation. The architecture of Differentiated Service consists of two basic sets of functions: Edge functions: include packet classification and traffic conditioning. At the inbound edge of the network, incoming packets are marked. In particular, the DS field in the packet header is set to a certain value. For example, in Figure 2.12, packets sent from H1 to H3 are marked at R1, while packets from H2 to H4 are marked at R2. The labels on the received packets identify the service class to which they belong. Different traffic classes receive different services in the core network. The RFC definition uses the term behavior aggregate rather than the term traffic class. After being marked, a packet can be forwarded immediately into the network, delayed for a period of time before being forwarded, or dropped. We will see that there are many factors that affect how a packet is marked, and whether it is forwarded immediately, delayed, or dropped. Figure 2.12 DiffServ Example Core functionality: When a DS-marked packet arrives at a Diffservcapable router, the packet is forwarded to the next router based on Per-hop behavior is associated with packet classes. Per-hop behavior affects router buffers and the bandwidth shared between competing classes. An important principle of the Differentiated Service architecture is that a router's per-hop behavior is based only on the packet's marking or the class to which it belongs. Therefore, if packets sent from H1 to H3 as shown in the figure receive the same marking as packets from H2 to H4, then the network routers treat the packets exactly the same, regardless of whether the packet originated from H1 or H2. For example, R3 does not distinguish between packets from h1 and H2 when forwarding packets to R4. Therefore, the Differentiated Service architecture avoids the need to maintain router state about separate source-destination pairs, which is important for network scalability. Chapter Conclusion Chapter 2 has presented and clarified two main models of deploying and installing quality of service in IP networks. While the traditional best-effort model has many disadvantages, later models such as IntServ and DiffServ have partly solved the problems that best-effort could not solve. IntServ follows the direction of ensuring quality of service for each separate flow, it is built similar to the circuit switching model with the use of the RSVP resource reservation protocol. IntSer is suitable for services that require fixed bandwidth that is not shared such as VoIP services, multicast TV services. However, IntSer has disadvantages such as using a lot of network resources, low scalability and lack of flexibility. DiffServ was born with the idea of solving the disadvantages of the IntServ model. DiffServ follows the direction of ensuring quality based on the principle of hop-by-hop behavior based on the priority of marked packets. The policy for different types of traffic is decided by the administrator and can be changed according to reality, so it is very flexible. DiffServ makes better use of network resources, avoiding idle bandwidth and processing capacity on routers. In addition, the DifServ model can be deployed on many independent domains, so the ability to expand the network becomes easy. Chapter 3: METHODS TO ENSURE QoS FOR MULTIMEDIA COMMUNICATIONS In packet-switched networks, different packet flows often have to share the transmission medium all the way to the destination station. To ensure the fair and efficient allocation of bandwidth to flows, appropriate serving mechanisms are required at network nodes, especially at gateways or routers, where many different data flows often pass through. The scheduler is responsible for serving packets of the selected flow and deciding which packet will be served next. Here, a flow is understood as a set of packets belonging to the same priority class, or originating from the same source, or having the same source and destination addresses, etc. In normal state when there is no congestion, packets will be sent as soon as they are delivered. In case of congestion, if QoS assurance methods are not applied, prolonged congestion can cause packet drops, affecting service quality. In some cases, congestion is prolonged and widespread in the network, which can easily lead to the network being "frozen", or many packets being dropped, seriously affecting service quality. Therefore, in this chapter, in sections 3.2 and 3.3, we introduce some typical network traffic load monitoring techniques to predict and prevent congestion before it occurs through the measure of dropping (removing) packets early when there are signs of impending congestion. 3.1. DropTail method DropTail is a simple, traditional queue management method based on FIFO mechanism. All incoming packets are placed in the queue, when the queue is full, the later packets are dropped. Due to its simplicity and ease of implementation, DropTail has been used for many years on Internet router systems. However, this algorithm has the following disadvantages: − Cannot avoid the phenomenon of “Lock out”: Occurs when 1 or several traffic streams monopolize the queue, making packets of other connections unable to pass through the router. This phenomenon greatly affects reliable transmission protocols such as TCP. According to the anti-congestion algorithm, when locked out, the TCP connection stream will reduce the window size and reduce the packet transmission speed exponentially. − Can cause Global Synchronization: This is the result of a severe “Lock out” phenomenon. Some neighboring routers have their queues monopolized by a number of connections, causing a series of other TCP connections to be unable to pass through and simultaneously reducing the transmission speed. After those monopolized connections are temporarily suspended, Once the queue is cleared, it takes a considerable amount of time for TCP connections to return to their original speed. − Full Queue phenomenon: Data transmitted on the Internet often has an explosion, packets arriving at the router are often in clusters rather than in turn. Therefore, the operating mechanism of DropTail makes the queue easily full for a long period of time, leading to the average delay time of large packets. To avoid this phenomenon, with DropTail, the only way is to increase the router's buffer, this method is very expensive and ineffective. − No QoS guarantee: With the DropTail mechanism, there is no way to prioritize important packets to be transmitted through the router earlier when all are in the queue. Meanwhile, with multimedia communication, ensuring connection and stable speed is extremely important and the DropTail algorithm cannot satisfy. The problem of choosing the buffer size of the routers in the network is to “absorb” short bursts of traffic without causing too much queuing delay. This is necessary in bursty data transmission. The queue size determines the size of the packet bursts (traffic spikes) that we want to be able to transmit without being dropped at the routers. In IP-based application networks, packet dropping is an important mechanism for indirectly reporting congestion to end stations. A solution that prevents router queues from filling up while reducing the packet drop rate is called dynamic queue management. 3.2. Random elimination method – RED 3.2.1 Overview RED (Random Early Detection of congestion; Random Early Drop) is one of the first AQM algorithms proposed in 1993 by Sally Floyd and Van Jacobson, two scientists at the Lawrence Berkeley Laboratory of the University of California, USA. Due to its outstanding advantages compared to previous queue management algorithms, RED has been widely installed and deployed on the Internet. The most fundamental point of their work is that the most effective place to detect congestion and react to it is at the gateway or router. Source entities (senders) can also do this by estimating end-to-end delay, throughput variability, or the rate of packet retransmissions due to drop. However, the sender and receiver view of a particular connection cannot tell which gateways on the network are congested, and cannot distinguish between propagation delay and queuing delay. Only the gateway has a true view of the state of the queue, the link share of the connections passing through it at any given time, and the quality of service requirements of the traffic flows. The RED gateway monitors the average queue length, which detects early signs of impending congestion (average queue length exceeding a predetermined threshold) and reacts appropriately in one of two ways: − Drop incoming packets with a certain probability, to indirectly inform the source of congestion, the source needs to reduce the transmission rate to keep the queue from filling up, maintaining the ability to absorb incoming traffic spikes. − Mark “congestion” with a certain probability in the ECN field in the header of TCP packets to notify the source (the receiving entity will copy this bit into the acknowledgement packet). Figure 3. 1 RED algorithm The main goal of RED is to avoid congestion by keeping the average queue size within a sufficiently small and stable region, which also means keeping the queuing delay sufficiently small and stable. Achieving this goal also helps: avoid global synchronization, not resist bursty traffic flows (i.e. flows with low average throughput but high volatility), and maintain an upper bound on the average queue size even in the absence of cooperation from transport layer protocols. To achieve the above goals, RED gateways must do the following: − The first is to detect congestion early and react appropriately to keep the average queue size small enough to keep the network operating in the low latency, high throughput region, while still allowing the queue size to fluctuate within a certain range to absorb short-term fluctuations. As discussed above, the gateway is the most appropriate place to detect congestion and is also the most appropriate place to decide which specific connection to report congestion to. − The second thing is to notify the source of congestion. This is done by marking and notifying the source to reduce traffic. Normally the RED gateway will randomly drop packets. However, if congestion If congestion is detected before the queue is full, it should be combined with packet marking to signal congestion. The RED gateway has two options: drop or mark; where marking is done by marking the ECN field of the packet with a certain probability, to signal the source to reduce the traffic entering the network. − An important goal that RED gateways need to achieve is to avoid global synchronization and not to resist traffic flows that have a sudden characteristic. Global synchronization occurs when all connections simultaneously reduce their transmission window size, leading to a severe drop in throughput at the same time. On the other hand, Drop Tail or Random Drop strategies are very sensitive to sudden flows; that is, the gateway queue will often overflow when packets from these flows arrive. To avoid these two phenomena, gateways can use special algorithms to detect congestion and decide which connections will be notified of congestion at the gateway. The RED gateway randomly selects incoming packets to mark; with this method, the probability of marking a packet from a particular connection is proportional to the connection's shared bandwidth at the gateway. − Another goal is to control the average queue size even without cooperation from the source entities. This can be done by dropping packets when the average size exceeds an upper threshold (instead of marking it). This approach is necessary in cases where most connections have transmission times that are less than the round-trip time, or where the source entities are not able to reduce traffic in response to marking or dropping packets (such as UDP flows). 3.2.2 Algorithm This section describes the algorithm for RED gateways. RED gateways calculate the average queue size using a low-pass filter. This average queue size is compared with two thresholds: minth and maxth. When the average queue size is less than the lower threshold, no incoming packets are marked or dropped; when the average queue size is greater than the upper threshold, all incoming packets are dropped. When the average queue size is between minth and maxth, each incoming packet is marked or dropped with a probability pa, where pa is a function of the average queue size avg; the probability of marking or dropping a packet for a particular connection is proportional to the bandwidth share of that connection at the gateway. The general algorithm for a RED gateway is described as follows: [5] For each packet arrival Caculate the average queue size avg If minth ≤ avg < maxth div.maincontent .s1 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 15pt; } div.maincontent .s2 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 15pt; } div.maincontent .p { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; margin:0pt; } div.maincontent p { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; margin:0pt; } div.maincontent .s3 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .s4 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s5 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s6 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .s7 { color: black; font-family:Wingdings; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s8 { color: black; font-family:Arial, sans-serif; font-style: italic; font-weight: bold; text-decoration: none; font-size: 15pt; } div.maincontent .s9 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .s10 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 9pt; vertical-align: 6pt; } div.maincontent .s11 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 13pt; } div.maincontent .s12 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 10pt; } div.maincontent .s13 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-d
Basic electronic engineering - City College of Construction. HCM Part 1 - 1
Organizing physical education teaching activities at People's Security College I in the current reform period - 14
Classification Table of Overdue Debt Ratio by Collateral of Seabank

Procedure: Soak peanuts in hot water, remove the silk shell, put the white peanuts in a mortar, add an equal amount of distilled water and grind thoroughly into a smooth paste, add the remaining water and grind well, rub through gauze to collect the emulsion.

6.2. Potio emulsion

Potio has 3 types: main potio, emulsion potio and suspension potio.

Potio emulsion combines water-soluble and oil-soluble pharmaceutical ingredients and additives into a homogeneous liquid form.

Example: Rp Bromoform 2g

Sodium benzoate 4g

Codeine phosphate 0.2g

Single syrup 20g

Oil emulsion v.s. 100ml

Mf potio

Oil phase: includes oil of oil emulsion and Bromoform

Water phase: distilled water of emulsion, simple syrup, codeine phosphates and sodium benzoate. Emulsifier gum arabic 9g.

Procedure: weigh and grind 9g of gum arabic/clean, dry mortar. Dissolve 2g of bromoform in 10g of vegetable oil, add the oil phase to the gum, stir gently to absorb the gum evenly, add 18ml of water, use a pestle to beat quickly and continuously to get a thick emulsion.

Dissolve sodium benzoate in 20ml hot water then dissolve codeinphosphas.

Use the remaining water to dilute the thick emulsion, then mix the sodium benzoate solution, codeine phosphates and simple syrup into the diluted emulsion, adding enough water to make 100ml.

Bottled and labeled properly, with the words “shake before use” added to the label.

6.3. Medicinal oil emulsion

Oil emulsions are prepared from pharmacologically active oils. They may or may not dissolve additional synergistic active ingredients and additives. The oil ratio is very high, so a mixture of emulsifiers must be used: gum arabic – agar – jelly or tween – span.

Example Rp Paraffin Oil 35g

Tween 80 and span 80 6g Distilled water q.s. 100ml

Procedure: weigh paraffin oil into a glass cup, heat water at 60 o C and dissolve span into hot oil.

Heat water to about 65 o C, dissolve tween 80 into hot water.

Combine two phases using dispersing force to create an emulsion and pass the emulsion through a homogenizer.

Bottled and labeled properly, with the words “shake before use” added to the label.

6.4. Injectable emulsions

Prepared from fats such as vegetable oils: soybean oil, sesame oil, olive oil for infusion to provide fatty acids and energy for the body.

The size of the oil phase should be approximately 0.5µm in diameter (< 1µm and no particles > 1µm).

Strong, non-toxic, easily metabolized emulsifiers such as de-cephalinized lecithin and hydrogenated to saturate fatty acids or polysorbate (Tween) or polyglyceryl monooleate (Demol), polypropylene derivatives with PEG (Pluronic).

Increase viscosity with glucose, sorbitol, glycerol. Antioxidant tocopherol 0.1%.

Prepare under sterile conditions, store in silicon-lined vials and in an inert atmosphere (nitrogen).

Substances that do not change the composition of blood and cause red blood cells to clump. For example: Cotton seed oil 15ml

Dextrose 4 g

Lecithin 1.2 g

Pluronic F.68 0.3 g

Distilled water to 100ml

Combine oil and lecithin. Heat to 70 o C.

Add Dextrose and Pluronic F.68 to water, heat to 90 o C.

Mix the two phases together and then disperse them in a homogenizer. Bottle. Steam for 20 minutes at 15 PSI (1kgf).

Currently, sterile emulsions for injection are usually prepared by homogenization at high temperature and pressure, by which emulsions with a size smaller than 1 µm can be prepared. For sterilization, heat or filtration can be used.

VALUATION

I. Choose true or false:

1. Sterile emulsions for injection are usually prepared by homogenization at moderate temperature and pressure.

2. Medicinal oil emulsions are prepared from oils that have no pharmacological effects.

3. Natural emulsions are prepared from oil seeds and have no pharmacological effects.

4. When preparing medicated oil emulsions, it is conventional to use one part of the granules to make 10 parts of emulsion. Answer:

5. When preparing an emulsion, the longer the stirring time and the greater the dispersion force, the easier it is for the emulsion to form.

6. D/N emulsions are more easily formed when oil is added to water. Answer:

7. Changing pH will change the emulsification mechanism of Gelatin. Answer:

8. PEG is an emulsion stabilizer due to increasing the viscosity of the medium. Answer 9. Oral emulsions are N/D type emulsions. Answer

10. A concentrated emulsion is one where the concentration of the dispersed phase is less than 10% of the total system. Answer:

II. Fill in the blanks:

1. Injectable emulsions are prepared from fats such as vegetable oils to provide

.....(A)..... and ...(B)..... for the body.

2. In the oil-medicinal emulsion, the oil phase ratio is ...(A).... so a mixture of .....(B).... must be used such as: Gum ....(C).... or tween-span

3. In natural emulsions, the oil phase is ....(A)...., the water phase in the emulsion is....(B)....... and the emulsifier ..(C).... is present in the seeds.

4. The main disadvantage of emulsions is.......

5. In an emulsion, the oil phase includes all the active ingredients and the carrier or excipients.

.....(A).... The aqueous phase consists of liquids or is dissolved in liquids....(B)....

6. To evaluate the quality of emulsion, people rely on the following parameters:

A. Shape and size of dispersed phase particles B. .........................................

C. ...... of the dispersion medium and the dispersed phase.

D. Decomposition time and ..........

7. The stable emulsifiers commonly used in preparing emulsions are: .....(A)......., Polyvinylic alcohol and .....(B).........

8. Normally, depending on the nature of the emulsifier, two types of emulsions will form:

....(A)... and .....(B).....

9. Emulsions are microheterogeneous mechanical dispersions formed by two liquids ....(A)..... In which one liquid is .....(B).... into the second liquid.

10. Drug emulsion consists of three main parts: .....(A)......., Emulsifier and .....(B)....

III. Choose the best answer:

1. Tweens belong to the group of surfactants:

A. Ionization, cation

B. Non-ionizing, for D/N emulsions

C. Non-ionizing, for N/D emulsions

D. Bisexual

2. Gum arabic belongs to the group of emulsifiers:

A. Active surface

B. Synthetic water-based adhesive.

C. Natural water-based glue, used for D/N emulsions

D. Natural water-based glue, used for N/D emulsions

3. Cholestrol is an emulsifier and wetting agent used to prepare:

A. Cream D/N B. Lotio

C. Potio emulsion D. Ointment emulsion N/D

4. The ratio of gum arabic used to emulsify the oil base is mainly based on:

A. Gum quality

B. Density of dispersant

C. Viscosity of the dispersion medium

D. pH of the dispersion medium

5. To determine the parameters of the emulsion, we rely on the following factors:

A. Dispersion phase ratio.

B. Viscosity of the dispersed phase

C. Shape and size of particles of the dispersion medium

D. Decomposition time of emulsifier

6. The emulsion is more stable when:

A. The greater the concentration of the dispersed phase

B. The smaller the concentration of the dispersed phase

C. The larger the size of the dispersed phase particles

D. Low viscosity of dispersion medium.

7. Emulsifiers in the form of small particles are:

A. Solids that dissolve in water and do not dissolve in oil

B. Solids that are soluble in oil and insoluble in water

C. Solid insoluble in water and oil in the form of very fine powder

D. Solid insoluble in water and oil in the form of semi-fine powder

8. Saponins:

A. Easily soluble in water, is an emulsifier that creates N/D emulsions

A. Easily soluble in water and oil, is an emulsifier that creates D/N emulsions

C. Easily soluble in water and alcohol, is an emulsifier that creates D/N emulsions

D. Easily soluble in water and alcohol, is an emulsifier that creates N/D emulsions

9. Carbohydrates are substances that:

A. Has large molecules and is easily soluble or swells in oil

B. Has large molecules and is easily soluble or swells in water

C. Has small molecules and is easily soluble or swells in water

D. Has large molecules and is easily soluble in water.

10. The type of emulsion depends on:

A. Solubility, permeability and emulsifier ratio

B. Solubility, permeability and dispersion ratio

C. Solubility, permeability and substance ratio of the dispersion medium

D. Solubility and permeability of emulsifiers.

IV. Answer the following questions:

1. Describe the concept and advantages and disadvantages of emulsion?

2. Given the formula:

Castor oil 30g

Gum Arabic 10g

Peppermint essential oil 3 drops

Gum syrup 20g

Distilled water to 100ml

Find the method of emulsion preparation and type of emulsion?

3. Given the formula:

Paraffin oil 500ml

Adragant Gum 2.5g

Gum Arabic 50g

Jelly 5g

Lemon essential oil 1ml Vanillin 0.2g

Sodium benzoate 1.5g

Glycerin 50ml

Distilled water 1000ml

Find the right combination of emulsifiers?

4. Given the formula:

Paraffin oil 50g

Polyethyleneglycol 400 7g

Sodium bezoate 0.2g

Single syrup 20g

Distilled water to 100ml

Look for emulsifier in the formula, type of emulsifier and method of preparation?

5. Describe the types of emulsions and how to identify the type of emulsion?

6. Describe the technique of preparing emulsions by separating each co-miscible solvent phase with two phases?

7. Describe the technique of preparing emulsion using wet and dry glue methods?

8. List the factors that affect the formation and stability of emulsions?

CHAPTER 7

MEDICINAL SUNSCREEN

TARGET

1. Describe the definition, classification, and composition of drug suspensions.

2. Analyze the advantages and disadvantages of drug mixtures

3. Describe common methods of preparing drug mixtures.

4. Analyze the composition, methods and preparation sequence of some drug suspensions on the market.

CONTENT:

1. General

1.1. Definition

Drug suspensions are liquid medicines for oral, injection, or topical use containing insoluble solid pharmaceutical ingredients dispersed uniformly in the form of very small particles (diameter greater than 0.1 micrometers) in a carrier such as water or oil.

The term “Milk” is sometimes used to refer to suspensions with an aqueous carrier intended for drinking (e.g. Milk of Magnesia). The term “Magma” is often used to describe suspensions of inorganic solids such as bentonite dispersed in water, which have a strong tendency to hydrate and to aggregate the solid particles to produce a viscous texture and thixotropic rheology.

The term “Topical” is used to classify suspensions and emulsions applied to the skin for topical action.

Complete suspension for immediate use: Is a cloudy liquid or liquid with a layer of sediment at the bottom of the bottle, when shaken gently this sediment must be evenly dispersed back into the carrier.

Powder or granule form: Before use, convert into a complete suspension by shaking with an appropriate amount of carrier.

The suspension is not for intravenous or intra-arterial use.

1.2. Classification of suspensions

1.2.1. According to the origin of the conductor

- Water suspension - Oil suspension - Glycerin suspension

1.2.2. By route of administration

- Oral suspension

- Suspension for subcutaneous and intramuscular injection (not for intravenous or spinal injection)

- External suspension

1.2.3. According to particle size

Coarse suspension is a heterogeneous dispersion of solid particles larger than 1  m, with the maximum limit of solid particles in the range of 50 - 75  m.

Colloidal suspension (collodial suspension) also known as turbid suspension is a micro-heterogeneous dispersion system of solid particles with size smaller than 1  m, for example aluminum hydroxide and magnesium hydroxide suspension. In colloidal suspension, the size of solid particles is almost as small as colloidal particles, so they follow Brownian motion and other thermodynamic phenomena, so they are quite stable and often in a turbid liquid state.

1.3. Ingredients

 Pharmaceutical substances

The main active ingredients are solids that are insoluble or very slightly soluble in the carrier. There are two types:

type:

- Insoluble type but has a surface of particles that are easily permeable in the dispersion medium

- Type of conductor that is difficult to penetrate

 Distributed environment

- Dispersion medium includes water and polar liquids, or oil and other substances.

nonpolar liquid

- There are also pharmaceutical preservatives, flavoring agents, and anti-mold preservatives.

1.4. Characteristics of drug suspension

- The outstanding feature is that the drug has a mechanical dispersion structure, so it is not thermodynamically stable, the dispersed phase will gradually separate from the dispersion medium.

- Suspension is a cloudy liquid or liquid with a layer of sediment at the bottom of the bottle. When shaken, the sediment will disperse back into the cloudy liquid.

- Regarding naming the mixtures, they are named according to their usage.

- In terms of physics and chemistry, suspensions are heterogeneous dispersions, composed of a solid dispersed phase and a liquid dispersion medium.

1.5. Advantages and disadvantages of drug mixtures

1.5.1. Advantages

- Solid drugs that are insoluble or slightly soluble in carriers can be prepared in liquid form, and drugs can be introduced into the body through more routes than when prepared in solid form; oral medications are easier for children.

- Limits the disadvantages of some drugs when dissolved, they will not be stable, have an unpleasant taste, and irritate the digestive mucosa (antibiotics).

- Make the drug work slower but last longer or limit the effect of the drug locally.

- Limit the toxic effects of some drugs.

1.5.2. Disadvantages

- It is a heterogeneous dispersion system, thermodynamically unstable, difficult to prepare and unstable.

- If not prepared and used carefully, the dosage will not be accurate and may be harmful to the patient.

1.6. Quality requirements for suspension drugs General requirements :

When left undisturbed, the solid drug can be separated but must return to a state of homogeneous dispersion in the carrier when gently shaken for 1 - 2 minutes and maintained in that state for several minutes.

Requirements for pH, qualitative, quantitative, volume error and other technical requirements : Meet the regulations in the separate monograph.

Suspension for injection or eye drops :

Must meet the requirements for Sterility Testing and particle size requirements specified in the specific monograph.

Powder or granules for mixing suspension :

Must meet the general requirements of Powder or Granule form.

When left alone, the dispersed solid may separate into separate layers but must return to a state of uniform dispersion in the carrier. Gently shake the bottle for 1-2 minutes and maintain that state of dispersion for several minutes.

2. Factors affecting the formation, stability and bioavailability of drug suspensions

2.1. Effect of permeability of dispersion medium of insoluble solids .

For the suspension to form and stabilize, the solid particles must be permeable to the dispersion medium.

- Solid hydrophilic drugs are easy to prepare to meet the requirements of liquid drug suspensions.

- Solid, water-soluble pharmaceuticals are easy to prepare to meet the requirements of oil suspensions.

To make the solid drugs hydrophilic into hydrophilic, people use molecular surfactants with two parts: hydrophilic and hydrophilic. When added to the two solid-liquid phases of the molecular suspension, the surfactant will orient the contact surface of the two phases to create a molecular membrane, ions are created around the solid particles, reducing the surface tension between the two phases, so the solid particles are more permeable to the carrier.

In addition, hydrophilic colloids or some very small particle hydrophilic inorganic solids are also used to convert hydrophilic solids into hydrophilic ones.

When preparing injectable and topical drug suspensions, surfactants are used as permeating agents.

To prepare oral suspensions, people use hydrocolloids or hydrophilic solids in the form of small particles as permeating agents.

2.2. Effect of two-phase density

The smaller the difference in density between the dispersed solid drug and the dispersion medium liquid, the more stable and sustainable the suspension will be.

2.3. Effect of dispersed particle size

The smaller the size of the dispersed particles (due to the strong dispersing force and the ability of the wetting agent to disperse like a surfactant), the easier it is to form and stabilize the suspension.

2.4. Effect of viscosity of the carrier

The greater the viscosity of the carrier, the easier and more stable the suspension will be.

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