1. Introduction of Doxycycline hydrochloride
Doxycycline hydrochloride, with the systematic name of (4S,4aR,5S,5aR,6R,12aS)-4-(dimethylamino)-3,5,10,12,12a-pentahydroxy-6-methyl-1,11-dioxo-1,4,4a,5,5a,6,11,12a-octahydrotetracene-2-carboxamide hydrochloride, is one kind of yellow crystalline powder. What's more, it is a synthetic tetracycline derivative with similar antimicrobial activity. And it is used in some areas for the treatment of chloroquine-resistant falciparum malaria.

2. Properties of Doxycycline hydrochloride
Physical properties about Doxycycline hydrochloride are: (1)# of Rule of 5 Violations: 2; (2)ACD/BCF (pH 5.5): 1; (3)ACD/BCF (pH 7.4): 1; (4)ACD/KOC (pH 5.5): 1; (5)ACD/KOC (pH 7.4): 1; (6)#H bond acceptors: 10; (7)#H bond donors: 7; (8)#Freely Rotating Bonds: 7; (9)Polar Surface Area: 181.62 Å²; (10)Flash Point: 421.4 °C; (11)Enthalpy of Vaporization: 118.07 kJ/mol; (12)Boiling Point: 773.2 °C at 760 mmHg; (13)Vapour Pressure: 3.72E-25 mmHg at 25°C.

3. Structure Descriptors of Doxycycline hydrochloride
You could convert the following datas into the molecular structure:
(1)SMILES: Cl.CN(C)[C@@H]3C(\O)=C(\C(N)=O)C(=O)[C@@]4(O)C(/O)=C2/C(=O)c1c(cccc1O)[C@H](C)[C@H]2[C@H](O)[C@@H]34
(2)InChI: InChI=1/C22H24N2O8.ClH/c1-7-8-5-4-6-9(25)11(8)16(26)12-10(7)17(27)14-15(24(2)3)18(28)13(21(23)31)20(30)22(14,32)19(12)29;/h4-7,10,14-15,17,25,27-29,32H,1-3H3,(H2,23,31);1H/t7-,10+,14+,15-,17-,22-;/m0./s1
(3)InChIKey: RUYHIJHUVHIMIR-CVHRZJFOBJ

4. Toxicity of Doxycycline hydrochloride

Organism	Test Type	Route	Reported Dose (Normalized Dose)	Effect	Source
dog	LD50	intravenous	> 100mg/kg (100mg/kg)		Drugs in Japan Vol. -, Pg. 840, 1995.
dog	LD50	oral	> 500mg/kg (500mg/kg)		Drugs in Japan Vol. -, Pg. 714, 1990.
mouse	LD50	intraperitoneal	179mg/kg (179mg/kg)		Drugs in Japan Vol. -, Pg. 714, 1990.
mouse	LD50	intravenous	201mg/kg (201mg/kg)		Drugs in Japan Vol. -, Pg. 840, 1995.
mouse	LD50	oral	1890mg/kg (1890mg/kg)		Drugs in Japan Vol. 6, Pg. 505, 1982.
mouse	LD50	subcutaneous	700mg/kg (700mg/kg)		Yakuri to Chiryo. Pharmacology and Therapeutics. Vol. 8, Pg. 1447, 1980.
rat	LD50	intraperitoneal	714mg/kg (714mg/kg)		Drugs in Japan Vol. -, Pg. 840, 1995.
rat	LD50	intravenous	137mg/kg (137mg/kg)	SENSE ORGANS AND SPECIAL SENSES: OTHER CHANGES: OLFACTION LUNGS, THORAX, OR RESPIRATION: RESPIRATORY DEPRESSION BEHAVIORAL: SOMNOLENCE (GENERAL DEPRESSED ACTIVITY)	Yakuri to Chiryo. Pharmacology and Therapeutics. Vol. 8, Pg. 1447, 1980.
rat	LD50	oral	1700mg/kg (1700mg/kg)	SENSE ORGANS AND SPECIAL SENSES: PTOSIS: EYE BEHAVIORAL: MUSCLE WEAKNESS LUNGS, THORAX, OR RESPIRATION: RESPIRATORY DEPRESSION	Yakuri to Chiryo. Pharmacology and Therapeutics. Vol. 8, Pg. 1447, 1980.
rat	LD50	subcutaneous	700mg/kg (700mg/kg)		Yakuri to Chiryo. Pharmacology and Therapeutics. Vol. 8, Pg. 1447, 1980.

5. Safety Information of Doxycycline hydrochloride
When you are using Doxycycline hydrochloride, please be cautious about it as the following:
Doxycycline hydrochloride is harmful if swallowed. It is irritating to eyes, respiratory system and skin. Whenever you will contact it, please wear suitable protective clothing and gloves. In case of contact with eyes, you should rinse immediately with plenty of water and seek medical advice.